Common Cat & Dog Eye Problems
Diseases of the eyes are relatively common and can be due to injuries, health concerns, breed, or genetics. Signs of an eye problem should be seen by an ophthalmology specialist to ensure your pet is properly diagnosed and treated.
Our veterinarians have spent years specializing in veterinary ophthalmology, so they could help ease discomfort and restore vision in pets. We are also dedicated to the education of pet owners so that they are able to spot the signs of disease before they become advanced.
Early treatment is the key, so knowing the signs can help keep your pet happy and healthy, and help maintain their vision and quality of life for years to come.
If your pet is showing signs of an eye issue, don't wait for it to fix itself, ensure your pet gets the appropriate care they need.
Signs Your Pet Has an Eye Issue
The condition of your pet's eyes can offer insight into the condition of their overall health and well-being. While some eye conditions are mild and can be managed at home, others can be quite serious and threaten your pet's vision and health.
Some indications that your pet is experiencing an eye condition may include redness, tearing, squinting, and rubbing of the eyes.
Although these symptoms can be relatively common, they may still warrant a trip to the vet. Your vet may be able to provide some at-home solutions to resolve the problem. Avoid attempting to treat, or apply medication to their pet's eyes before consulting with a veterinary professional. When it comes to your pet's eyes, it is always best to err on the side of caution.
When to See Your Vet
Eye conditions in companion animals will require veterinary ophthalmology care, and cannot be cured by home remedies. If there are any concerning symptoms in your pet's eyes, seek veterinary assistance.
When looking at your pet's eyes, if you notice symptoms such as excessive discharge, cloudiness, unequal pupil sizes, swelling, a visible third eyelid, or vision loss, it is time to see the vet immediately.
The veterinary team at can thoroughly examine your pet's eyes and develop an appropriate treatment plan. We can care for your pet's eyes whether they are enduring a mild eye condition like an infection or conjunctivitis, or a more serious condition like glaucoma, cataracts, or cherry eye which may require surgery.
List of Common Pet Eye Diseases
The following are some of the more common eye diseases treated by our Renton, and Kirkland vets every day.
Bartonellosis is caused by infection with one of five Bartonella species of bacteria including Bartonella henselae. This is the bacterium that can cause "cat scratch" disease in people. The bacteria can be transmitted between cats by fleas and ticks. The bacteria can be spread to people primarily by cat scratches and bites. Most infected people do not become ill. However, since it is a potentially zoonotic disease (can be transmitted from animals to humans), you should bring any concern to your physician. Cats can remain infected for years or even for life if untreated. Most infected cats show no signs of illness. There is some disagreement amongst veterinarians as to what Bartonella infection can do to cats. The organism has been blamed for causing a variety of problems in cats including oral, respiratory, intestinal, and ocular diseases.
Potential Ocular Effects of Bartonella Infection:
Bartonella infection in cats has been implicated as causing conjunctivitis, uveitis, blepharitis, chorioretinitis, and keratitis.
The conjunctivitis attributed to Bartonella infection is commonly both chronic and refractory to a variety of treatments. Yet, it can respond rapidly to oral azithromycin therapy. The biggest differential for Bartonella conjunctivitis is herpesviral conjunctivitis. Dual infection is also a possibility.
We mostly think of Bartonella as a pathogen in cats but there is at least one report of it causing ocular effects in dogs as well.
Proving that Bartonella infection is the cause of a cat's clinical signs can be difficult. Diagnosis is made by evaluating the clinical signs in conjunction with a blood test to look for a high level of antibodies to this organism. Drawbacks to this type of testing include the facts that there can be false negatives (meaning the cat is infected but antibody negative; occurs up to 11% of the time) and that a positive titer might only indicate exposure to the organism and not active infection. Other diagnostic tests available include blood culture and PCR but these tests have their own drawbacks and can be more expensive and time-consuming.
Bartonella infection is usually treated with a 3-week course of the oral antibiotic azithromycin. This course of therapy has been shown to clear infection in 83% of affected cats. If repeat testing (see below) indicates inadequate therapy, another course of treatment will probably be recommended. Control of flea problems is also important to prevent re-infection. The main side effects of azithromicin therapy are gastrointestinal ones (vomiting, decreased appetite, and diarrhea). If side effects occur, please let us know right away.
Evaluation of Bartonella Therapy:
Six months following therapy, repeat blood testing is advised to assess the adequacy of treatment. This is an "antibody titration test". Titers are determined by serial dilutions on both the pre-and post-treatment blood samples. This testing is much more involved than the initial testing. It is therefore more time-consuming and more expensive. It can take as long as one month to get these results, compared to about 10-14 days for the initial blood test. Keep in mind that this follow-up testing is still important even if the ocular signs have resolved. Otherwise, there is potential for ocular signs to recur and/or for health problems to show up in other organ systems.
A cataract is any opacity (cloudiness) of the lens. If the opacity involves a significant portion of the lens, your pet may exhibit visual difficulty. Heredity, metabolic diseases such as diabetes mellitus, congenital (birth) defects, trauma, or other eye diseases may be responsible for cataract formation.
Your pet must be in good general health to be considered as a potential candidate for cataract surgery, largely because cataract surgery is performed with your pet under general anesthesia. Routine bloodwork is usually necessary prior to surgery, so that the doctor may more thoroughly evaluate your pet's health. Diabetic patients must have their blood sugar levels regulated with insulin prior to surgery.
A preoperative examination by a veterinary ophthalmologist is necessary to determine if your pet is an acceptable candidate for cataract surgery.
The cataract may induce inflammation within the eye, which is called uveitis. The success rate of cataract surgery might be decreased by the presence of uveitis. If inflammation is noted at the time of examination, cataract surgery may be delayed for a short period until the inflammation can be decreased with medications.
The retina comprises the nervous tissue of the eye that is necessary for vision. If the retina is significantly diseased, cataract surgery will not improve your pet's vision. The retina lies behind the cataract and cannot be visualized in cases of advanced cataract development. If the doctor cannot visualize the retina, retinal testing by electroretinography and/or ultrasonography will be recommended.
If your pet is determined to be a candidate for cataract surgery, the surgical success rate varies by patient but is 90% for the optimal candidate. This assumes that all postoperative recommendations are followed including treatments and examinations. Without the proper follow-up, complication rates significantly increase. In the 10% or so where major complications develop, these are sometimes manageable but blindness can be the result. In some cases, additional surgery can even become necessary.
Although general anesthesia is required for cataract surgery in animals, cataract surgery is performed on an outpatient basis. Your pet must stay with us for the day of surgery and must return to the clinic the following day for the first postoperative examination.
Cataract surgery in animals is very similar to cataract surgery for people. The technique used to remove the cataract is called phacoemulsification. The procedure basically employs the use of high frequency sound waves to fragment the cataractous lens, which can then be removed from the eye as a liquid.
Once the cataract is removed, your pet should regain vision but far-sightedness will result (near objects will be out of focus). In order to correct for this far-sightedness, we offer the option of replacement with an artificial lens (IOL). Artificial lenses serve to focus light rays on the retina and to correct for near vision. Most patients are candidates for IOL placement. Occasionally, the decision cannot be made until the time of surgery that the eye is not suitable for an IOL.
The cost of cataract surgery primarily depends upon whether one or both eyes have surgery and upon whether the lenses are replaced with artificial intraocular lenses. In addition, the cost for diabetic dogs is generally higher than for non-diabetic dogs, partially due to the requirement for frequent blood sugar determination. If you would like to know more about the process or the pricing, feel free to call us.
Included in the price of surgery:
- General anesthesia
- Anesthetic monitoring (including pulse oximetry, ECG, blood pressure, and CO2 monitoring)
- Preoperative medications
- Cataract surgery
- Two postoperative examinations
Not included in the price of surgery:
- Preoperative examinations
- Preoperative medications
- Retinal evaluation
- Medications disepensed on surgery day
- Recheck examinations after second postoperative exam
- Refills on medications after surgery
- Preoperative bloodwork
- Capsular tension rings
- Any lasering procedures performed at the time of cataract surgery
Postoperative care is vital to a successful outcome from cataract surgery. Your pet's vision depends on strict adherence to our recommendations for medical therapy and recheck examinations. Medical therapy is usually the most intensive for the first 1-2 weeks after surgery. Most patients remain on decreasing levels of medical therapy for at least 4 months after surgery. Occasional patients require long-term medical therapy.
The eye should be considered fragile after surgery. All precautions should be taken so that your pet does not damage the eye(s). The protective Elizabethan collar should be worn by your pet until directed otherwise (generally for the first 3 weeks after surgery). Activity should be restricted for the first month after surgery.
Recheck examinations are important for the doctor to determine the condition of the eyes and to advise you on medical therapy. The number of appointments will depend upon your pet's progress, but 4-6 examinations are typically required during the first 6 months after surgery. Annual examinations are recommended for long-term monitoring.
Vision-threatening complications can develop after surgery and must be monitored for closely. Early detection of a complication maximizes the chance that it can be successfully managed. The most common of the serious complications are glaucoma and retinal detachment.
-For more information on cataracts and cataract surgery, please enjoy the ACVO video Cataracts, You and Your Pet on YouTube!
Prolapsed gland of the third eyelid ("cherry eye")
When the tear-producing gland of the third eyelid pops out of position, it protrudes from behind the third eyelid as a reddish mass at the inner corner of the eye. This prolapsed tear gland condition is commonly referred to as "cherry eye". The problem is most commonly seen in young dogs and particularly in certain breeds of dogs such as the Cocker Spaniel, Bulldog, and Lhasa Apso.
Despite its dramatic appearance, a prolapsed third eyelid gland does not always produce detectable signs of ocular pain. However, the longer the gland is exposed, the more likely it is to become irritated and inflamed. It can even ulcerate and hemorrhage, especially if your pet rubs at the eye. Furthermore, the function of the gland can be compromised if the gland is exposed for long periods of time. The resultant damage can be permanent (dry eye).
To correct "cherry eye", surgical replacement of the gland is necessary. This treatment is far superior to the old approach where the prolapsed gland was merely removed. The gland of the third eyelid plays a vital role in maintaining normal tear production. We now know that dogs that have had the gland removed are predisposed to developing the "dry eye" condition. "Dry eye" (or keratoconjunctivitis sicca-KCS) is uncomfortable for the patient and can lead to blindness if not treated successfully. Furthermore, treatment of "dry eye" is usually required for life. Additionally, cases of KCS that result from third eyelid gland removal can be extra challenging to control. To reduce the chances for this condition, it is preferable to surgically reposition the tear-producing gland so that it can continue to function properly.
One procedure used to correct "cherry eye" is called the "pocket technique". Although the gland cannot be put back into its original position in the third eyelid, a new pocket is made near the original position. The tear gland is tucked inside the pocket and the pocket is sutured closed. For most animals, this is the most successful approach. However, there is no technique that results in success 100% of the time. Recurrence rates vary by breed. Recurrence is most common in the Bulldog and Mastiff breeds. For other breeds, success rates are 90-95% so long as the condition is not allowed to become too chronic before surgery and so long as the postoperative instructions (eg., E-collar use, activity restriction) are followed.
If only one gland has prolapsed at this time, please be aware that the other eye could become affected with the problem in the future. Please contact us should this occur. Sometimes a procedure will be recommended to try to prevent gland prolapse in the second eye. This condition is considered genetic in most affected animals, thus this trait could be passed on if your pet is used for breeding.
Chronic Superficial Keratitis ("Pannus")
Pannus is inflammation of the cornea causing opacification and, eventually, visual impairment from the infiltration of blood vessels and pigment.
Blood vessels, granulation tissue (fibrovascular tissue) and white blood cells (lymphocytes and plasma cells) invade the superficial corneal stroma.
The main presenting sign is a change in the appearance of the cornea. Pannus does not usually seem painful, despite being unsightly. If the cornea becomes diffusely pigmented, vascularized or scarred, visual impairment may be noted. Some dogs also develop thickening and changes in pigmentation of the third eyelid, called "Atypical Pannus" or plasmoma.
There is likely an immune-system trigger to attack the ocular tissues. Other contributing factors include breed, sunlight exposure, and high altitude (>4000 feet). German Shepherd Dogs and greyhounds are at increased risk, although any breed can be affected.
A complete ophthalmic exam is needed to differentiate pannus from other causes of vascularization and pigmentation of the cornea. Specifically, we test for dry eye and other tear film abnormalities and evaluate for abnormal eyelid conformation, abnormal eyelashes contacting the cornea and corneal ulcerations.
Topical immunosuppressive drugs are usually effective in controlling the disease, so long as they are applied consistently and as directed. Typically, these therapies consist of corticosteroids (Prednisolone, dexamethasone), tacrolimus and/or cyclosporine. In rare, refractory cases, oral immunosuppressive agents are also required. Surgical removal of the tissue is rarely performed because the condition is expected to return and the corneal thickness and strength are diminished with surgery.
The condition can be controlled, but not cured. Life-long topical medications are usually needed.
Corneal Endothelial Degeneration
A bluish haze to the cornea caused by loss of the deepest corneal cells.
The corneal endothelial cells line the inner portion of the cornea. One of their main functions is to pump fluid from the cornea to keep it relatively dehydrated. The dehydrated state and regular arrangement of tissue maintains clarity. The cells have poor regenerative capacity when damaged. There is age-related decline in these cells. In some animals, cellular loss is accelerated and/or extreme. When function is impaired, fluid builds in the cornea, causing it to swell.
Opacity of both corneas is usually the initial sign and this often starts at the lateral aspect of the eye and progresses to involve the entire cornea. Some dogs may show visual impairment, but this is usually mild, except in advanced cases. Often, painful corneal ulcers develop due to the rupture of fluid-filled vesicles (bullae) and/or poor corneal health.
Advanced age, breed, intraocular inflammation and/or intraocular surgery can be contributing factors. It is most often seen in Boston terriers, Dachshunds, and Chihuahuas.
Slit-lamp examination reveals thickening of the cornea. Bullae and/or ulcers can be seen when they are present. It is important to evaluate the interior of the eye for inflammation, and to measure intraocular pressure as high pressure or intraocular inflammation can also cause corneal opacity.
Medical treatment is possible with topical hyperosmotic agents, such as 5% NaCl (sodium chloride). The high salt content draws fluid out of the cornea. It is most effective to limit ulcer formation but is not effective in all patients and some patients show discomfort with application; clearing of the corneal cloudiness should not be expected with its use. Ulcers are treated with topical antibiotics and pain management. Procedures to aid ulcer healing are commonly needed.
Surgeries to tack areas by scarring with thermal cautery (thermokeratoplasty) or to place a thin conjunctival graft over the area are used. Both leave scarring, which can impair vision, but can be effective to prevent ulcerations. In human beings with analogous conditions, a full-thickness or endothelial corneal transplant replaces the lost endothelial cells. In dogs, graft rejection is usually severe and this procedure is not routinely performed.
Once the condition forms, it is life-long. Many dogs do not require treatment of any kind. Most dogs are managed well with medications and/or surgeries to control ulcer formation.
Corneal lipid (cholesterol) deposits are common in dogs and uncommon in cats. In dogs, there are 3 main causes:
An inherited condition called corneal dystrophy. This is usually noticed initially just in one eye but eventually progresses to affect the second eye. The appearance varies between breeds, but most commonly these are cloudy spots in the center of each eye. It is quite rare that they progress to a point where there is significant vision loss. If this occurs in a dog to be used for breeding, the condition could be passed on.
Commonly affected breeds include the Cavalier King Charles Spaniel, Siberian Husky, Shetland Sheepdog, Collie and Beagle. This condition is usually non-painful though occasionally, particularly in Shelties, it can cause episodes of pain and chronic medical therapy (or even surgery) is sometimes indicated.
If there is chronic irritation of a cornea, one of the ways it can respond is to degenerate. Part of the degenerative process can include deposition of cholesterol. In this situation, the problem usually affects just one eye, is associated with another eye problem, and there is usually inflammation (blood vessels) in the affected region of cornea. The best treatment in this case is to address the underlying cause.
Corneal degeneration is common in geriatric dogs. In this instance, the lipid deposits are usually associated with an even greater mineral component. This can be a greater problem if there are health problems, such as kidney disease, causing problems with calcium and phosphorus levels. Blood work might be recommended to help evaluate the problem. In the geriatric pets, ongoing medical therapy is usually needed in the advanced stage. Sometimes a deep piece of degenerated cornea will be sloughed from the eye resulting in a serious corneal ulcer. This can necessitate intensive medical therapy and/or surgery to save the eye.
When cholesterol deposits are found in cat corneas, they are usually due to degeneration that results from a chronic herpesviral infection.
The last main type of corneal lipid deposition is lipid keratopathy that can occur due to a high blood cholesterol level. In other words, the eye problem is the result of a systemic (generalized) health problem. For example, hypothyroid dogs can have very high blood cholesterol levels. Sometimes this first manifests in the eye(s) as corneal opacities. It usually affects both eyes but might initially show up in just one eye. Besides hypothyroidism, other underlying causes include Cushing's Disease, diabetes, inherited problems with lipid metabolism (e.g., Miniature Schnauzers), and even high-fat diets.
Remember that health problems do commonly first show up in eyes as this is the one part of the body we can see directly into. Therefore, just because your pet is still acting healthy at this point does not mean that there are no other problems.
The most important thing is to have a proper diagnosis as to a) if that is lipid in the cornea, and then b) WHY it is present. Many dogs have these fatty deposits and function just fine with minimal, if any, effect on vision. However, without proper diagnosis so that any underlying causes can be addressed, the eye(s) can get worse, vision can decline, and other signs of illness can arise.
If there are any questions about your pet's diagnosis, please let us know.
To understand corneal sequestration, it helps to have some knowledge of feline corneal anatomy. The cornea is the (normally) clear surface of the eye. The outside layer is called the epithelium. It is somewhat similar to skin, though it is normally free of pigment, hair, or blood vessels for the sake of vision. If the epithelium is missing, by definition there is a corneal ulcer. These are usually painful because nerve endings are quite dense in the superficial cornea. The bulk of the cornea is comprised of stroma. The total cat cornea is less than 1 mm thick. For comparison, a dime is 1 mm thick.
Corneal sequestration (or formation of a corneal sequestrum) is a condition that only affects cats. In this condition, the stroma (the supporting tissue or matrix of the cornea) degenerates and turns a brown to black color. The color change is due to absorption of tear pigments into the dead corneal tissue. A sequestrum will look like a brown to black "plaque" or "scab" on the eye. It may be elevated from the rest of the eye surface. There will be variable degrees of cloudiness surrounding the sequestrum. The body tends to treat this area as a foreign substance and will attempt to slough the affected area. Unfortunately, this process can take months to years if the eye is left to heal on its own. In the meantime, the cat is usually painful (or at least irritated) and vision declines. The surface layer or epithelium of the cornea cannot adhere to a sequestrum, thus the eye will have a chronically open wound if a sequestrum is present. This causes pain and puts the eye at risk for infection.
There are several causes for a corneal sequestrum, and they all have the common theme of chronic corneal irritation. The main causes are herpetic infection of the eye, injured cornea with aberrant healing, low tear production (usually associated with herpes), poor tear quality, inability to completely or normally close the eyelids over the eye, insufficient frequency of blinking, or entropion (inward rolling of the eyelid, commonly due to herpesviral infections). Some breeds are predisposed to this condition, including Persians and Himalayans.
The problems with untreated sequestra are chronic ocular pain, decreased vision, and potential for either infection or rupture of the eye. Remember that pain can be difficult to evaluate in cats. Their instinct is to hide pain. The vast majority of cats seem to feel better once a sequestrum is removed.
In most cases, surgical removal of a sequestrum is the ideal course of treatment. This generally elicits the quickest recovery and elimination of pain. Rarely, medical therapy and monitoring will be recommended if the sequestrum is loose and about to be spontaneously extruded. There is some risk for recurrence of the sequestrum at the same location. To reduce the risk for recurrence and to promote healing, a graft is commonly placed over the surgical site.
Medical therapy will be required until the eye has healed from surgery, and some recheck examinations will be required. You should find that the path to recovery is much quicker with the surgical approach. The cat cornea tends to heal very well after this type of a surgery. The appearance of the eye will improve greatly over the first 6 months after surgery, with a concurrent improvement of vision.
Please let a member of our team know if you have more questions or concerns.
Indolent corneal ulcers
A corneal ulcer is a defect in the surface layer of the eye, called the epithelium. In its simplest form, a corneal ulcer can be considered similar to a scrape on your skin. The cornea is densely packed with nerve endings for pain perception, thus corneal ulcers can be very painful. As a cornea with an ulcer has lost its normal protective surface layer, the eye becomes at risk for an infection. This is significant as corneal infections are quite serious and can lead to loss of vision and/or the eye.
A normal corneal ulcer should heal within 5-7 days. Characteristics of an indolent ulcer include an ulcer that does not heal within this period of time and may actually increase in size. Oftentimes, indolent ulcers will change shapes over subsequent examinations. This can be misleading as it can mimic early healing. Upon examination of the eye, an indolent ulcer does not have any evidence of infection and no cause can be found which would prevent the ulcer from healing. Indolent ulcers can become chronic and may persist for 6 months or more without specific treatments. Other names for this type of ulcer are Boxer ulcer, refractory ulcer, refractory epithelial erosion, chronic corneal erosion, and spontaneous chronic corneal epithelial defect (SCCED).
An indolent ulcer is felt to be due to an abnormality of one or more of the layers of the cornea, the corneal epithelial basement membrane and/or superficial stroma. For this reason, many affected animals have recurrent indolent ulcers due to the presence of a primary corneal abnormality. These ulcers can form spontaneously without trauma. An injury can certainly be a trigger in some cases.
There are many treatments available for indolent ulcers. Some of these ulcers will respond to corneal debridement and placement of a contact lens on the eye. Although this is the least invasive and least expensive approach, it is only about 50% successful. The procedures associated with the highest success rates for healing are called a keratotomy (grid or punctate) and a keratectomy. The keratotomy has a 95+% success rate for healing of indolent ulcers. It can usually be done with the patient awake and using topical anesthetic. Many patients are given a sedative/analgesic to alleviate both anxiety and pain during the procedure. In some cases, including those that do not respond to the keratotomy, a keratectomy is the ideal option. This surgery is associated with nearly a 100% success rate. The major disadvantages are that it requires general anesthesia and that it is more invasive and expensive than a keratotomy. A diamond burr polishing technique is another highly-effective option for some cases.
Regardless of the procedure chosen in order to get your pet's ulcer to heal, medical therapy will be recommended in order to reduce the risk for development of a secondary infection and to control ocular pain. It is also important that your pet does not rub at the eye, thus you may be provided with a protective Elizabethan collar in order to prevent this problem.
Most dogs will heal well after the keratotomy procedure, but this disease can be frustrating, especially in the more stubborn cases. Try to have patience, and together we will work to get the ulcer to heal and to get your dog feeling better as soon as possible.
Distichiasis is a condition where eyelashes emerge from a structure in the eyelid (meibomian gland) which does not normally produce hairs. These "extra eyelashes" emerge so close to the eye that they can contact the ocular surfaces and can cause discomfort and corneal damage. Distichiasis is considered an inherited problem as it is much more common in certain breeds of dogs including Shih Tzus, Lhasa Apsos, Golden Retrievers, and Cocker Spaniels.
The severity of the problem and the need for treatment vary from patient to patient. Some patients may have only a few, soft distichia on a single eyelid while others may have full rows of abnormal hairs on all eyelids. Although some patients with distichia are asymptomatic, many animals require treatment in order to alleviate irritation caused by the hairs rubbing on the cornea of the eye. Signs that can be indicative of ocular irritation include redness of the eyes, squinting, ocular discharge/tearing, and/or rubbing at the eyes.
Sometimes distichia can cause corneal ulcers or erosions when the hairs touch the cornea of the eye. Corneal ulcers can be very painful and can lead to vision loss in severe cases.
Pulling out the abnormal hairs in the exam room may provide temporary relief, but these lashes almost always grow back. Topical ointments may be used to help lubricate the eyes, which can provide some relief from the abnormal hairs. Depending upon the patient, surgery might be recommended as the ideal approach.
There are several surgical options for distichiasis. The one that shows the highest success rate and is therefore usually the approach recommended at Northwest Animal Eye Specialists is cryosurgery. For low numbers of distichia, electroepilation might be used instead. Cryoepilation works by freezing the affected area of the eyelid to kill the hair follicle. Although electroepilation or cryosurgery should prevent the distichia from growing back in the treated areas, there are numerous places along the lids where new distichia could potentially emerge. Additionally, there are occasionally stubborn follicles that are resistant to cryosurgery, which can result in a recurrence at that site. For these reasons, up to 10% of dogs will require a second procedure in order to eliminate any new aberrant hairs. This is more of a concern in young and/or severely affected dogs.
The main side effects that may result from these surgeries are eyelid swelling, loss of eyelid pigmentation, and/or loss of hair in the affected areas. In most cases, these effects are only temporary.
Keratoconjunctivitis Sicca (Kcs Or "Dry Eye")
A common problem of animal eyes, most common in dogs is keratoconjunctivitis sicca (KCS or "dry eye" syndrome). Some causes of "dry eye" include congenital disorders (puppies), surgical removal of the tear-producing gland of the third eyelid ("cherry eye"), administration of certain medications (e.g., sulfa antibiotics, Etogesic anti-inflammatory drug), and infections such as distemper. Most cases are considered "immune-mediated" and result from attack by the animal's own immune system on their own tear-producing glands. The disease is seen very commonly in certain breeds such as the Cocker Spaniel, Shih Tzu, Lhasa Apso, Bulldog, Schnauzer, and West Highland White Terrier.
The clinical signs of "dry eye" include large amounts of ocular discharge (that re-forms quickly after cleaning), redness of the eyes, rubbing at the eyes, cloudy eyes, and corneal ulcers. After an extended period of dryness, the surface of the eye (the cornea) begins to accumulate pigment and blood vessels. If this is allowed to progress, blindness can be the result! It is therefore important that the tear production be normalized rapidly.
Our treatment goals for KCS include stimulation of tear production, controlling secondary infections, and decreasing corneal scarring. Treatment is very effective if the condition is diagnosed early, but life-long treatment is usually required. The drug cyclosporine is anywhere from 50-90% effective in stimulating normal tear production in dogs, depending on the severity of the disease by the time of diagnosis. A newer KCS treatment, tacrolimus, is an option for severe cases, including those where cyclosporine has failed. It is effective in some, but not all, of the cases where cyclosporine has failed. Cyclosporine and tacrolimus must be used as directed. If the medication is discontinued, the signs will usually recur. It can be more difficult, or impossible, to get controlled the next time around. It is very important to have your pet's eyes periodically monitored in order to evaluate the success of treatment and to determine if any changes in treatment are required.
Parotid Duct Transposition (PDT) Surgery
Parotid duct transposition is a surgery to reroute the duct of the parotid salivary gland to provide substitute lubrication to the eye with saliva in place of tears. This procedure is reserved for patients that are non-responsive to medical therapy for KCS or dry eye. These patients have little to no improvement in tear values as measured by a Schirmer tear test (STT) with a measurement of <5 mm/minute, as opposed to the goal of a normal STT value of >15 mm/minute. Due to the extreme dryness, most patients will be uncomfortable as evidenced by frequent blinking, rubbing and squinting. They may also be experiencing decreased vision due to corneal pigmentation and scarring resulting from KCS.
Prior to surgery, a dental cleaning should be performed if needed to reduce bacteria in the mouth. Additionally, function of the salivary gland can be confirmed with a drop of atropine or other bitter substance on the gums and observation of the duct opening for saliva.
The PDT surgery is performed under general anesthesia with either an open or closed technique. The only difference is the open technique involves making an incision on the side of the face in addition to the one inside the mouth in the gum tissue above the upper premolars. The duct is cannulated with suture material and freed from surrounding tissue until it can be redirected into the conjunctival sac and sutured into place.
In general, the success rate is 80-90 % for flow of saliva and resolution of discomfort. The most common complication of PDT surgery is accumulation of calcium/mineral deposits on the cornea from the saliva. A topical medication called EDTA may be used to reduce the deposits. Other issues that can occur include too much flow, resulting in facial dermatitis or stricture/obstruction of the duct.
After surgery, swelling of the face and lower eyelid/conjunctiva area is to be expected. Cold pack application for the first several days will help that resolve. Both topical and systemic antibiotics are prescribed to combat infection. An Elizabethan collar is required to prevent self -trauma and disruption or premature removal of sutures during healing. Frequent small feedings are recommended to keep the duct open and saliva flowing, especially during the initial healing phase.
Entropion is the inward rolling of all or part of the eyelid and can affect anywhere from one to all four of the eyelids. The result of this eyelid inversion is that the hair from the eyelid skin rubs on the corneal and conjunctival surfaces. With mild entropion, in which there is little inversion and contact with the ocular surfaces, there may only be low-grade discomfort and excessive tearing. When the irritation is severe, however, the patient will have chronic pain and serious injury can develop. Self-trauma, due to the irritation, can contribute to the overall damage as well. Entropion is a significant problem because if it remains uncorrected, it will persist as a chronic source of discomfort. Ultimately, sight can be affected because of corneal inflammation, scarring, pigmentation, and/or ulceration.
Most developmental (primary) entropion demonstrates a clear breed predisposition. Although the genetic basis has not yet been clearly defined, the problem is likely the results of genes responsible for overall head and facial conformation. The problem is common in Shar Peis, Chow Chows, Bulldogs, Pugs, Retrievers, and Rottweilers. It is occasionally seen in cats as well, where it is typically a secondary type of entropion.
Most cases of primary entropion will deveop by 6 months of age. Occasionally, spontaneous (primary/developmental) entropion will not appear until after 12 months of age, especially in large breeds of dogs. Entropion is usually a surgical disease. However, entropion in an immature animal may improve spontaneously with growth. Mild cases in young dogs may be managed medically or with temporary eyelid "tacking" sutures until maturity. Surgery might be delayed until the age of 4-6 months, except in severe and complicated cases.
Trauma, chronic inflammation, and painful eye diseases can lead to acquired or secondary entropion. "Spastic entropion", which results from eyelid spasms due to ocular pain, might resolve with placement of temporary tacking sutures and control of the underlying painful eye disease(s). It is more likely to resolve if addressed early and aggressively. Surgical correction might be necessary, but the entropion will recur if the underlying cause goes uncorrected or uncontrolled. The cause, location, and extent of entropion and presence of concurrent problems determine the corrective technique recommended.
The success rates with surgery vary somewhat based on the breed, age, and specifics of the case. In general, surgery is successful about 90-95% of the time. In up to 10% of patients, there are extenuating circumstances (e.g., young animal, recurrence or persistence of underlying causes if secondary entropion, other) that necessitate a second procedure.
Entropion in cats most commonly results from a severe or chronic herpetic infection of the eye. Unfortunately, by the time it develops, it is typically permanent damage and does not resolve with successful treatment of the underlying infection. Surgery is usually required to resolve this type of secondary entropion. This is one case where control of the underlying cause is critical, since herpes in cats is commonly a chronic or recurrent problem.
It is common for Pugs to have entropion of the inner aspect of the lower eyelid. The result is that the eyelid hairs rub on the cornea. Pug corneas tend to pigment easily with this sort of irritation. In the early stages, the pigment will be confined to the inner aspects of the cornea. If left untreated, the pigment commonly progresses across the cornea. It is not uncommon at all for the cornea to become completely pigmented if the underlying entropion remains. The damage to the cornea is called pigmentary keratitis and is a common cause of blindness in Pugs. It is much easier to prevent the pigment formation that to deal with it once it develops. Pugs with this type of entropion usually respond favorably to a procedure called medial canthoplasty. It involves narrowing of the eyelid opening with partial closure at the inner corner. The cosmetic result is not dramatic (once healed).
Eosinophilic Keratitis And Eosinophilic Conjunctivitis
Eosinophilic keratitis and eosinophilic conjunctivitis are unique syndromes found in cats (and horses). A particular type of white blood cell (the eosinophil) normally responds when allergy or parasites affect the body. In patients with eosinophilic keratitis, these white blood cells invade the cornea and give the eye a pinkish, white, and/or chalky appearance. In the same fashion, eosinophilic conjunctivitis affects the conjunctival tissues covering the sclera (white part of the eye) and the undersides of the eyelids.
Although the cause in many cases is unknown, there is an association with feline herpesvirus infection of the eye. Treatment for eosinophilic keratitis/conjunctivitis is usually medical and may include one or more of the following types of medications: topical anti-inflammatories, topical antivirals, and/or oral anti-inflammatory medications. Injections of steroids next to the affected eye(s) can be beneficial, especially in severe cases or for cats who are difficult to treat topically or consistently. Treatment is usually successful, but it may take several weeks or longer for resolution of signs. Recheck examinations are usually advised to determine if the condition is controlled, if additional treatments are required, and when therapy can be discontinued. As recurrences are fairly common with this disease (at least 1/3 of cases), it is important to make sure that the condition is 100% controlled before considering discontinuation of therapy. In some cases where recurrences are a problem, long-term therapy might be advised to try to prevent damage from repeat recurrences.
Feline Herpes Virus
Feline Herpesviral Infections
Ocular infection with the feline herpesvirus is extremely common in cats. The virus is everywhere. Most cats are exposed as kittens. Kittens may be infected by the mother cat even at birth. Thus, they may be infected even before their eyes have opened!
During the initial infection, the kitten typically shows all the signs of an upper respiratory infection including sneezing, nasal discharge, and possibly a decreased appetite. Ocular signs are present as well and range from ocular discharge, swelling, and squinting. Most kittens are able to recover from this type of infection within 1-2 weeks. They may never show any signs again, however, the virus will persist in their system in a latent state. Cats may carry the virus for years without showing any signs. Asymptomatic carriers may shed the virus. Recurrences of ocular signs are possible at any point in the future, especially after stressful events. Fortunately, it is the minority of cats that have these relapses.
Most of the cats that come to this practice with signs of a herpes infection are actually having a flare-up of a previously latent infection. Your cat may have had the initial infection before you even got him or her. Thus the diagnosis may come as a total surprise to you. In many adult cats, only one eye is affected.
It is important for you to realize that the feline form of herpesvirus is species-specific. In other words, it will not be transferred either to you, other family members, or dogs. Other cats are susceptible. Fortunately, it is rare for there to be an "outbreak" within a household of adult cats. Most cats have already been exposed and have apparently mounted an immune response to the infection. Very young and very old cats are the most sensitive. Certain medical conditions and certain medications (eg., prednisone) can increase the risk for herpetic eye problems.
Minimization of stress is important to the control of your cat's eye problem. Many cats that show signs of a herpetic infection do so after a stressful event such as illness, surgery, boarding, or the acquisition of a new pet in the household.
Unfortunately, the diagnostic tests that are currently available to definitively diagnose a herpes infection are unreliable. This is particularly true for chronic cases. The doctor may recommend testing in select cases. Most of the testing on our feline patients where we suspect a herpes infection is to rule-out secondary bacterial infections, alternative diagnoses, or other complicating factors (eg., eosinophilic disease).
The diagnosis of an ocular herpetic infection is best made by the doctor's evaluation of the history of the eye problem, the signs in your particular cat's eyes, as well as the response to therapy. Most of the cats that we see have already been treated medically and did not exhibit an appropriate response to therapy. This is in itself suggestive of a herpes infection.
The most important thing to remember is to try to remain patient. These types of infections can resolve quickly with antiviral treatments but some cases are extremely challenging to control. "Cure" is not a reasonable goal as there is not anything available to eliminate this virus from your cat's system. The goals of treatment are to eliminate the signs of infection, to control ocular pain, and to prevent damage to the eyes that can lead to vision loss.
The antiviral medications available to treat this condition only inhibit, but do not destroy, the virus. This means that your cat's immune system is extremely important to our goal of getting the active infection "into remission". If your cat has a weak immune system due to age, immunosuppressive viral infections (eg., FIV or FeLV), or other medical conditions, it is likely to be particularly challenging getting the eye problem under control.
Medical therapy for your cat will most likely include an antiviral drop or ointment. The frequency of treatment with these medications is very important because the drugs are only inhibiting the virus and not killing it. Treatment is likely to be required for at least 3 weeks (and for 1 week beyond remission of signs). Many cases require more chronic therapy. The most commonly used drugs in this category are idoxuridine and cidofovir. An oral treatment, famciclovir (Famvir) is used in some severe cases.
An antibiotic may be used if herpetic corneal ulcers are present and/or if there are signs of a secondary bacterial infection. A bacterial infection can quickly accelerate the rate of damage to the eye(s) by the virus. Atropine may be used to control pain in the eye. It will dilate the pupil in treated eyes and thus create some light sensitivity, but it can help to make your pet less painful during the healing period. Oral pain killers are sometimes necessary for extremely painful pets.
L-lysine is an amino acid (protein building block) that has shown some antiviral effects against both cat and human herpesviruses. It is a safe supplement that can be given to your cat to help inhibit the life cycle of the virus. It should be given with food, as it can cause vomiting if given on an empty stomach. It can be used long-term. It is available in many forms including tablet, capsule, fish-flavored powder (to mix with food), and oral paste. One of our doctors can give you the appropriate dosage. It is not usually effective as the sole treatment during an active infection. Its best use is either in combination with other antiviral treatments or for long-term use to reduce recurrences.
The herpes virus most commonly causes conjunctivitis (signs similar to "pink eye" of people) or corneal infection. Corneal infection may consist of cloudiness, redness, and/or corneal ulcers. The latter can be very painful.
The most common complications of a herpetic infection are scarring of the eye, non-healing corneal ulcers, corneal sequestration (brown degeneration of cornea, usually require surgery for healing), chronic tearing from the eye, eosinophilic keratitis or conjunctivitis, and inward rolling of the eyelids ("entropion"). Eosinophilic keratitis and conjunctivitis are conditions where there is infiltration of ocular tissues with the eosinophil, which is a type of inflammatory cell.
Due to persistence of the virus in your cat, recurrences are possible. An initial sign of flare-up can be upper respiratory signs. If your cat becomes sniffly or starts sneezing, please contact us about his/her eyes. In some patients, this is a good time to start antiviral treatments to try to prevent eye problems.
Herpes infections cause some of the most common eye problems of cats. There is not a week that goes by where we don't see a cat (usually many) with herpetic eye disease. We deal with this all of the time and are here to help you. Please call with questions or concerns.
Glaucoma is defined as an elevated pressure within the eye. If glaucoma is uncontrolled, the pressure will cause irreversible damage to the retina and optic nerve. This damage leads to blindness and can occur rapidly.
There is a constant fluid production within the eye. This fluid serves vital roles such as providing nutrition to the internal ocular structures. The drainage angle is a structure located inside the eye at the outer edge of the iris (the colored part of the eye). The drainage angle can be compared to the drain in your sink, which has holes that allow removal of fluid from the eye into the bloodstream. The constant production and outflow of fluid achieve a balance so that the normal pressure within the eye is maintained between 10 and 25 mmHg. Most cases of glaucoma in animals are due to compromise to the drainage angle of the eye. If the "drain holes" are compromised, the fluid is still being produced within the eye but cannot escape. Eventually, the intraocular pressure rises and the signs of glaucoma develop.
- Redness of the white part of the eye
- Squinting of the eye, indicating ocular pain
- Cloudiness of the eye
- Dilated pupil
- Loss of vision
- Enlargement of the eye
Note: Not all of these signs will be present in every glaucoma patient!
The most common cause of glaucoma is a primary abnormality at the drainage angle of the eye, which is usually genetic in origin. Certain breeds are at higher than normal risk for glaucoma, including the Cocker Spaniel, Chow Chow, Shar Pei, Bassett Hound, and Siberian Husky. Although the underlying lesion is considered a hereditary one and affected dogs are usually born with the underlying abnormality, the clinical signs of glaucoma do not usually appear until middle age.
Glaucoma can also develop secondary to another problem within the eye such as a tumor, inflammation, trauma, or lens dislocation (luxation).
A thorough examination of the eye is necessary in order to determine the cause of glaucoma and to determine the degree of damage to the eye from the elevated pressure. The intraocular pressure is measured with a tonometer and the drainage apparatus of the eye might be evaluated with a special type of lens applied to the eye (gonioscopy).
Glaucoma is more than just elevated intraocular pressure, so follow-up full eye examinations are important. Accurate monitoring cannot be based on intraocular pressure alone.
The management of glaucoma depends on the cause and the length of time that the glaucoma has been present. If there is potential for vision, a procedure (an IV injection or drainage of fluid from the eye) might be performed to rapidly decrease the pressure within the eye. Medical therapy consists of eye drops and/or pills designed to lower intraocular pressure.
Primary glaucoma is a serious disease, which eventually become refractory to medical therapy in most cases. Surgery is usually required to maintain vision long-term. The long-term visual prognosis is guarded, though the newest laser technology offers greater hope for these difficult cases. Laser surgery is generally the best surgical option for visual eyes with poorly-controlled glaucoma. The most common complications from surgery are excessive inflammation and pressure fluctuations during the early recovery period.
We are commonly asked why any procedure is needed at all for uncontrolled glaucoma if it is already a blind eye. The reason is that uncontrolled glaucoma is a painful disease whether the eye is visual or not. Though signs of pain are not detectable in some pets with chronic glaucoma, we feel that most are indeed painful based on how they improve after the glaucoma is controlled medically or resolved by surgery. The best options for a blind, glaucomatous eye are intraocular prosthesis, enucleation, or intraocular injection (ciliary ablation).
1) Intraocular prosthesis:
This usually produces the most natural and cosmetic outcome. The prosthesis is permanent and does not require any care. The most common problems that can occur with prosthetic eyes are any surface diseases of the eye (corneal ulcers and dry eye) as the cornea and conjunctival tissues are retained with this approach. After surgery, all glaucoma medications are discontinued on that eye. Some patients are not ideal candidates for this approach.
2) Enucleation (complete eye removal):
This surgery resolves the glaucoma, allows a biopsy to be performed, and no glaucoma therapy will be required postoperatively (on that eye). In many cases, an orbital implant is placed. This type of implant is not visible to you as it is underneath the skin. It improves the cosmetic outcome, though it is not an option in all cases.
3) Intraocular injection (ciliary ablation):
With this approach, the appearance of the eye is less predictable long-term, as the eye can gradually decrease in size and will appear cloudy due to cataract and/or corneal scarring. This is the least invasive option, but it is only successful 80-90% of the time (with primary glaucoma; success rate lower with secondary glaucoma).
4) Laser surgery:
We are pleased to be able to offer you the newest in glaucoma technology-endoscopic cyclophotocoagulation (endolaser). This involves lasering of the ciliary processes of the eye (tissue that produces fluid within the eye) through a tiny endoscope that is introduced into the eye after lens removal. The recovery period can be intense, but many of these dogs eventually come off all glaucoma medications and long periods of glaucoma control are commonly achieved. In some cases, a shunt is placed in the eye at the same time to help during the initial recovery period. If this option is being considering for your pet, you should also read our Endolaser Surgery handout. Although this procedure can be performed on blind eyes, it is usually reserved for visual eyes.
Unfortunately, other than surgery, there is no permanent cure for glaucoma. The long-term prognosis for maintaining vision in dogs with primary (heritable) glaucoma is poor. In an attempt to preserve vision, regular recheck appointments are very important to monitor trends of the intraocular pressure. This allows modification of medical therapy as needed.
The clinical signs of glaucoma may develop in only one eye initially. The other eye is generally prone to glaucoma and requires prophylactic treatment to delay the onset of glaucoma. If glaucoma is untreated, irreversible blindness can occur within 24 hours. GLAUCOMA IS AN EMERGENCY! Early detection and treatment of glaucoma are critical to preservation of vision.
If you feel that your pet's glaucoma is out of control or if you run out of glaucoma medication, we need for you to call or page (if after hours) right away. Do NOT wait until the next business day.
Golden Retriever Uveitis
Uveitis is defined as inflammation of the uveal tract, which includes the iris or "colored part of the eye". There are many causes for uveitis including cancer, immune-mediated disease, cataracts, and certain infections. There is an inherited form of uveitis that occurs in the Golden Retriever breed.
Golden Retriever Uveitis is a serious condition because it is chronic and can result in vision loss. One of the ways it can be such a threat to vision is by being such an insidious disease. Signs detectable to a pet owner can be limited to redness and minimal drainage, so the disease can progress to an advanced stage before affected pets are presented to a veterinarian.
In a large retrospective study, the mean age of affected dogs at the time of diagnosis was found to be 8.6 years (range 4.5-14.5 years). The majority of dogs are affected in both eyes. Some of the key features of this condition are pigment dispersion across the front surface of the lens and the presence of one or more uveal cysts within the eye. Fibrin (inflammatory material) is sometimes found within the eye and can be an ominous precursor for impending glaucoma.
Glaucoma and cataract formation are the most common complications of the Golden Retriever (Pigmentary) Uveitis condition. If vision is lost from this disease, it is usually from one or both of these complications. In the retrospective study mentioned, 46% of dogs had glaucoma and 37% had cataracts. The cataracts that form with this condition are problematic because these are not the ideal candidates for cataract surgery. Glaucoma can rapidly (within days) cause permanent vision loss, is painful, and is not always controllable with medical therapy alone. Surgical options might need to be pursued.
The prognosis for dogs affected with this condition is guarded. With early detection, consistent therapy, and regular monitoring, some affected dogs will go years without major complications and with maintenance of vision. But there are some dogs with more advanced forms or stages of the condition where it fails to respond to therapy and vision cannot be saved.
The question is sometimes asked why any treatments or monitoring are necessary in an eye that has already lost vision. The reason is that a blind eye can still be a painful one. Glaucoma pain is commonly occult, meaning no outward signs of pain are exhibited. Golden Retrievers are notoriously bad about complaining that their eyes hurt. They are such good dogs! We know that these issues must be painful, at least in the majority of dogs, because of the positive changes in attitude/activity once uveitis and glaucoma are controlled.
For the sake of your pet's vision and comfort, it is critical that you contact us ASAP if you detect a sudden change in the appearance of your pet's eye(s).
Horner's syndrome is a condition that can occur in dogs, cats, horses, and many other species. The symptoms generally include a sunken appearance to the eye (enophthalmia) small pupil (miosis), droopy upper eyelid (ptosis), and a prominent third eyelid. Horner's syndrome must be differentiated from the condition uveitis, which can produce similar signs.
Horner's syndrome is an intriguing and complex disorder that can be difficult to understand. A basic description of neurology is needed.
There are two major divisions within your nervous system. There is the part of your nervous system that you are aware of and have control over, and there is the part of your nervous system that is under automatic control. You can perceive cold, and in responding to that stimulus, consciously initiate all the actions that result in your putting on a jacket. But the shiver occurs without your control. Similarly, you do not have to think to make your heart beat.
The autonomic nervous system (the part you have no control over) itself has two divisions, the sympathetic and parasympathetic nervous systems. Under normal conditions, there is a fine balance between sympathetic and parasympathetic stimulation.
If someone attacks you with a knife, your pupils dilate, blood is shifted to your muscles, and your heart beats faster as you prepare to fight or flee. This is sympathetic stimulation.
The eye has both sympathetic and parasympathetic innervation. If something blocks the sympathetic impulses to the eye, there will be an overbalance of parasympathetic supply to the eye. The result is that the pupil will constrict and all of the muscles around the eye will relax. The eye will sink into the orbit, the third eyelid will become prominent, and the upper eyelid will become droopy. This is Horner's syndrome.
The nerve that carries sympathetic innervation to the eye takes a remarkable course as it travels from the brain to the eye. The nerve travels down the spinal cord from the brain, emerges in the chest cavity, and then finds its way up the neck along with the carotid artery and jugular vein. It continues through the middle ear and eventually enters the eye.
Horner's syndrome is associated with damage to the sympathetic innervation to the eye. The damage may have numerous causes, and may occur anywhere along the course of the nerve's route from the brain to the eye. Horner's syndrome may be associated with brain tumors, spinal cord injuries, chest tumors, injuries to the neck (fighting, choke collars), middle ear diseases, and a variety of neuropathies. The most common scenario is that no particular cause can be found.
Of all dogs diagnosed with Horner's syndrome, 90% or more are middle-aged to older Golden Retrievers. Cocker Spaniels are the second most commonly affected breed.
In most cases of idiopathic (no identifiable cause) Horner's syndrome, spontaneous recovery will occur in an average of 16 weeks, but it can take as long as 6 months. A thorough physical examination is warranted to help rule out any of the specific causes of Horner's syndrome. If, for any reason, there is suspicion that a particular case is not idiopathic, then it is prudent to pursue a diagnostic evaluation that could include pharmacological testing on the eye, bloodwork, radiographs, or even an MRI.
If idiopathic Horner's syndrome is diagnosed, only time can potentially resolve the condition. In the meantime, signs can be masked by topical treatments of phenylephrine eye drops 2-3 times daily. It doesn't resolve anything, but can improve the appearance of the eye and vision if it is being affected by the elevated third eyelid.
Normal Vision And Vision With A Dislocated Lens
The lens of the eye is an important structure for vision. In order to have normal vision, the lens must be optically clear (free of cloudy or opaque spots) and the lens must remain in the normal position. If the lens moves out of its normal position, light rays are not focused on the retina and the eye becomes either far-sighted or near-sighted (depending upon the direction of lens movement). More importantly, dislocation (luxation) of the lens typically leads to devastating (and with time, blinding) complications in the eye. These include inflammation (uveitis), glaucoma, and retinal detachment. These complications can be quite painful. Glaucoma is increased pressure within the eye. It causes rapid and irreversible vision loss if not treated quickly and appropriately, by damaging both the retina and optic nerve of the eye.
Why Does A Lens Dislocate?
The main causes for lens luxation are genetics and chronic inflammation within the eye (uveitis). Inherited dislocation of the lens notoriously affects certain breeds. The most common breeds to be affected are the terriers, especially the Jack Russell Terriers and the Fox Terriers. Other commonly affected breeds are Poodles, Beagles, Blue Heelers, and Shar Peis but any breed or mixed breed can be affected. Cats occasionally develop the same condition. In cats, lens dislocation is usually an age-associated degenerative change, or it develops due to chronic uveitis. Cataracts can also lead to dislocation of the lens in either species. The disease usually affects both eyes. Therefore, both eyes will receive a thorough eye examination.
Anatomy Of The Normal Lens Position:
In order to understand how the lens dislocates, one must first understand a little bit about the anatomy of the eye. The lens is normally held in place by numerous small fibers called lens zonules. The inherited condition of zonular weakness or the damaging effects of intraocular inflammation on these zonules will ultimately lead to rupture of lens zonules. When these hair-like fibers have all broken free, the lens can move freely within the eye. This is the point at which the complications such as glaucoma and uveitis typically develop.
Outcome Of Lens Luxation:
If a lens is dislocated, the eye is at high risk for vision loss. The lens movement affects the nutrition to the lens, thus a cataract can develop. Glaucoma is a frequent manifestation of lens luxation (or subluxation) and it can develop rapidly. The short-term incidence of glaucoma in dogs is 65% or greater. This type of glaucoma does not necessarily respond to medical therapy.
Treatment Of This Condition:
Medical therapy can temporarily alleviate some of the discomfort in some cases. It will not correct the problem, however. The ideal therapy, at least for anteriorly luxated lenses, is surgical extraction of the lens (assuming that there has not yet been permanent damage to the eye that would prohibit vision after surgery). If the condition has been chronic and/or has already caused permanent blindness, your pet may be a better candidate for a procedure directed at comfort, such as placement of a prosthesis or complete eye removal.
Time is of the essence when dealing with a subluxated or luxated lens. The difference between these terms is only a matter of the severity of the stage of disease. Either situation can cause pressure elevations within the eye. These are SERIOUS glaucoma attacks that can lead to complete and permanent blindness within several days or less. This is an emergency situation!
The goals of surgical removal of the lens are to maintain vision and to eliminate ocular pain. Even with surgery, the prognosis is guarded. However, for an anteriorly-luxated lens, the prognosis with surgery is 75-80% versus about 0% long-term without surgery. If vision loss occurs despite surgery, it is usually due to persistent glaucoma or retinal detachment.
Prior to making a final recommendation for surgery, your pet's general health needs to be evaluated. Preoperative blood tests are likely to be recommended. Retinal testing, consisting of ocular ultrasound and/or electroretinography, may be recommended to make sure that your pet is a candidate for lens removal surgery.
Once your pet has been evaluated, you will be given a price estimate for the surgery.
What Is Included In The Price Of Surgery?
- General anesthesia
- Anesthetic monitoring (including pulse oximetry, ECG, and CO2 monitoring)
- Perioperative medications
- The surgery itself
- Medications dispensed on surgery day
- Two postoperative examinations
What Is Not Included In The Price Of Surgery?
- Preoperative examinations
- Preoperative medications
- Preoperative bloodwork
- Retinal evaluation-if necessary
- Recheck examinations after the second postoperative exam
- Refills of medications after surgery day
What To Expect After Surgery?
Vision may be acutely worse after surgery, due to the inflammation associated with surgery, as well as the sudden change in refractive error due to loss of the lens. It would be like somebody suddenly changing your glasses or contact lens prescription while you are still stuck with the old pair. The animals seem to partially adapt to their postoperative far-sightedness, especially over the few months following surgery. When your pet goes home, vision may be fuzzy. It should improve as the inflammation decreases and with time. Try to be patient. Unless there is a complication, vision should return.
This surgery is not a "quick fix". The postoperative care is critical and is vital to a successful outcome of surgery. Medical therapy is usually the most intense and time-consuming during the first 1-2 weeks after surgery. Medical therapy will continue for at least 3 months after surgery, often at a gradually decreasing level. Some patients require long-term medical therapy. In these cases, it is typically due to ongoing pressure problems.
Since there are potential complications (primarily glaucoma or retinal detachment), long-term monitoring will be required. For this reason, multiple rechecks will be needed, especially during the first 3-4 months after surgery and usually 1-2 times per year for the rest of the pet's life. At these visits, potential complications can be addressed, and the medical plan can be tailored to your pet's progress.
The eye should be considered fragile after surgery. All precautions should be taken so that your pet does not damage the eye(s). The protective Elizabethan collar should be worn by your pet for 3 weeks or until directed otherwise by the doctor. Be aware that the E-collar can decrease both vision and hearing during its period of use.
You need to be really committed to these efforts at saving your pet's eyesight and prepared for the follow-up care and treatments that will be inevitable, even with a perfect surgery.
The main complications for which we will monitor after surgery are glaucoma, retinal detachment, or severe inflammation. If your pet is in the unfortunate percentage of animals that develop these problems despite surgery, they are oftentimes manageable so long as the doctor has the opportunity to treat them promptly. Please call us with any concerns after surgery. We really care about our patients and don't want you to worry.
Nuclear, or lenticular, sclerosis is a cloudiness of the lens seen in older animals.
New lens fibers are made in the periphery of the lens throughout life. As the lens ages, the fibers from the outermost portion are pushed inward by the newly formed fibers. This causes the inner portion of the lens to become denser and the appearance more cloudy. The normal arrangement of the fibers is not disrupted (unlike a cataract), so vision is not usually impaired. In geriatric animals, nuclear sclerosis can contribute to age-related decline in vision.
A bluish haze can be seen in the central portion of the lens with clarity remaining at the periphery, which is best visualized when looking at the eyes in dim light conditions or when the pupils are otherwise dilated. No significant changes in vision are caused by this condition, which differentiates nuclear sclerosis from diffuse cataract.
Nuclear sclerosis is a normal aging change. It is an expected finding in dogs older than 6 years of age and cats older than 8 years of age.
It is possible to pass light through nuclear sclerosis, allowing reflection from the shiny lining of the back of the eye ("tapetum") and also allowing visualization of the retina well on fundic examination.
No treatment is needed for this condition, as it is a normal aging process.
Progressive Retinal Atrophy (Retinal Degeneration)
Progressive retinal atrophy (PRA) is an inherited eye disease that is more common in certain breeds of dogs (eg., Labrador Retriever, Poodle, Cocker Spaniel) but it can affect any breed or even mixed breeds of dogs. The disease causes gradual blindness, which first affects vision in poor lighting conditions and eventually results in complete blindness months to years later. Since the vision loss is so gradual, many owners do not notice signs of a problem until vision is severely affected. There is no known treatment for PRA at this time. Current research is aimed at finding treatments for these devastating retinal diseases that affect both animals and humans.
Genetics play a vital role in causing this disease. If the relatives of your pet are known, they should have eye examinations performed in order to look for evidence of PRA. Affected animals should not be bred. There is now a blood test available to look for the genetic marker for this condition in certain breeds of dogs. The test can potentially identify affected dogs as young as puppies. This is particularly advantageous for breeders because otherwise an affected dog can be bred before there is any evidence for the condition. The test can also identify the carriers' status for the disease. This is mainly of importance for breeding animals because carriers will not show signs of the disease but can pass on an affected gene. Normal results do not totally rule out the possibility of PRA because it could be present but due to a different genetic defect.
An electroretinogram may be recommended for your pet in order to evaluate retinal function. This test will help to confirm or rule-out the diagnosis of PRA, and will also help to quantify how much retinal function remains at this time.
Most dogs will eventually adjust to their blindness, and their other senses seem to become more sensitive over time. It is important to keep the home environment as stable as possible, and objects should be kept in consistent locations. Pets should not be left outside unattended unless they are in a confined space such as a yard. In the early stages of this disease, your pet may function better if you provide ancillary lighting at nighttime (e.g., light in the yard, nightlights in the house). For more information on helping your pet to deal with blindness, refer to the book Living With Blind Dogs by Caroline Levine.
This condition is painless and we at Northwest Animal Eye Specialists feel that a good quality of life is still possible with PRA.
Pigment is a brown discoloration, composed of melanin granules. In this disease, the clear surface of the eye, the cornea, is affected. Another name for this condition is corneal melanosis.
Corneal pigment deposits result from pigmented cells from the peripheral tissues of the eye into the normally clear cornea. It rests in deep epithelial layer and/or surface of the layer underlying it, the stroma.
Brown color change to the corneal surface is present. The coloration can be more apparent in certain light conditions. Other signs of corneal inflammation can accompany the pigment, including blood vessels. The pigment can become so severe as to impair vision, especially when it involves the central cornea.
Chronic irritation, from inward turning of the eyelid margins allowing hairs to rub on the corneal surface (entropion), poor blink response allowing exposure, chronic corneal ulceration, or diminished tear production allowing drying of the corneal surface can contribute to the condition. In rare cases, even when the underlying cause has been corrected, pigment will continue to form.
Evaluation includes measurement of tear production, application of fluorescein stain and close examination of position of the eyelids, both at rest and when blinking. Corneal sensitivity may be tested. Photos may be taken to document current appearance. Examinations over time are indicated to monitor for progression.
Control of the underlying condition(s) is usually the first step, with some cases requiring eyelid surgery and other cases requiring tear stimulating medications. In some cases, medications, such as Tacrolimus or Cyclosporine, are helpful to reduce pigmentation or prevent progression.
Pigment is only rarely surgically removed, and only if it is significantly impairing vision, since these surgeries weaken the cornea, leave scarring, can have healing complications or recurrence of pigmentation.
The pigmentation is likely to progress if the condition causing the pigment deposition is not successfully treated. Many pets need life-long, consistent medical treatment to prevent progressive damage.
Proptosis is the forward displacement of the eye in the socket to become trapped in front of the eyelids.
The eye is normally held in place by the extraocular muscles, soft tissues and eyelids to remain inside the bony orbit of the skull. The optic nerve exits the back of the eye traveling to the brain.
The eye is prominent with the inability to blink the eyelids over the surface. The tissues surrounding the eyes become very inflamed, preventing return of the eye to its normal position. Bleeding inside of the eye and tearing of the muscles responsible for eye movement are common. Occasionally, there will be damage to the tissues surrounding the eye, either from the initial injury or from the patient following the incident. If the cornea is not lubricated, corneal ulcers are seen.
Trauma is the most common cause, occurring after dog fights and car accidents. Occasionally, the incident causing proptosis of the eye is not witnessed.
Although the eye condition is unsightly, injuries such as head trauma, lung bruising or internal bleeding need to be stabilized before replacement is performed. Assessment requires a complete physical exam, and in some cases radiographs.
In all cases where there is the potential for vision, replacement of the eye into the correct position and suturing of the eyelids are recommended once the patient is stable for general anesthesia. In some cases, an incision needs to be made into the eyelid to facilitate replacement. The skin sutures are usually left in place for at least 2 weeks. In cases where significant damage has occurred to the eye, removal of the eye may be recommended rather than replacement.
Prognosis is related to head conformation and extent of damage to the eye and optic nerve. Here are some criteria, in general:
- Dog with short noses (brachycephalic)
- Signs of vision, light response
- Cats and dogs with long noses
- Blood inside the eye (hyphema)
- Globe rupture, retinal detachment
It is uncommon for vision to be preserved, but many dogs can retain a cosmetic eye. In some dogs, corneal ulcers occur, related to decreased corneal sensitivity from damage to the nerves supplying the cornea and/or decreased tear production. Muscles controlling eye position can be torn, causing the eye to turn (usually outward). Glaucoma from high pressure or shrinkage of the eye are also possible outcomes. Proptosis can recur at a later time.
Retinal Detachment and Hemorrhages
Retinal detachment is separation between the neurosensory retina and the layer underlying it. Retinal hemorrhage is blood within the retina or pooled in front of or behind the retina.
Retinal detachments can form by three mechanisms:
- Material that builds behind the retina, pushing it forward. This substance can be fluid, cells and/or proteins
- A tear in the retina
- Traction on the retina from the attachment to the vitreous or membranes
- Retinal hemorrhages are formed when blood is liberated from the vessels, which can occur from vessel rupture, vessel leakage and/or poor clotting ability
Loss of vision is the major sign of retinal detachment, but occurs only when are large area of the retina is affected and is difficult to routinely detect in patients with normal vision in the contralateral eye. In cases of complete detachment, the retina can become displaced forward and may be visualized through the pupil touching the back of the lens. With long-term detachment, increased iris blood vessels can form and contribute to glaucoma.
Causes of retinal detachment are numerous and include high blood pressure, breed-predisposition, intraocular surgery, intraocular inflammation, systemic infections, immune-mediated conditions, cancer, trauma, and congenital eye malformations.
Causes of hypertension include hyperadrenocorticism, hyperthyroidism, kidney failure, diabetes mellitus and tumors.
Systemic infections include fungal, tick-borne, protozoal and bacterial organisms.
Breeds predisposed to detachment include Bichon Frise, Shih Tzu, Miniature Poodle, and Labrador Retriever, among others.
Causes of retinal hemorrhage include high blood pressure, decreased blood platelets, decreased clotting factors, diabetes mellitus and cancer.
The retina is examined by indirect and/or direct ophthalmoscopy. A complete retinal exam requires pupil dilation, although this is not possible or advised in select cases. We evaluate for retinal tears, hemorrhages or inflammation; the appearance of the detachment guides diagnosis of the cause. Screening lab work and/or tests for specific diseases may be needed. If hypertension is suspected, blood pressure will be measured. Blood pressure is measured in dogs and cats similar to how it is measured in people, with the cuff placed on a shaved region of a limb or the tail.
For both retinal detachment and retinal hemorrhages, treatment of the underlying disease is most important. For many causes, this results in resolution of the detachment. In cases of breed or surgery-related detachments where a tear is present, retinal reattachment surgery may be indicated.
Regular rechecks are needed to assess retinal reattachment in response to therapy. If systemic disease is present, we will partner with your regular veterinarian and/or other specialists involved in your pet's care.
For small detachments that only need laser surgery to prevent progression, it can be performed at this hospital. Retinal reattachment surgery is a highly specialized procedure and performed by only a handful of veterinary ophthalmologists in the country. The surgery involves entering the eye to break down attachments between the retina and vitreous, repositioning the retina, and then securing the retina in place with laser. This procedure is not performed at Northwest Animal Eye Specialists, but we refer cases that would benefit from surgery to a hospital that provides it.
Prognosis for vision depends on the underlying cause, duration of detachment, response to treatment and concurrent ophthalmic disease. Even extensive detachments have the potential to reattach with return of vision. With retinal tears, prognosis depends on time from detachment until surgery, with a duration of 4 weeks generally cited as the maximal amount of time for a reasonable prognosis for vision to be considered.
Sudden Acquired Retinal Degeneration (SARDS)
Sudden acquired retinal degeneration syndrome (SARDS) is a retinal disorder of unknown cause that results in an acute onset of permanent blindness in adult dogs. Affected dogs are typically middle-aged to older, and all breeds can be affected. There is no evidence to suggest that this disease is hereditary, and there is not any known means of preventing the condition. There is no proven treatment available for this condition.
The primary complaint is always acute vision loss. Most dogs will go completely blind within four weeks of the noticeable onset of vision loss, and many dogs will have total vision loss within one to two weeks. Some owners notice the first signs of poor lighting conditions.
Though many dogs have no clinical signs of illness other than blindness, some dogs will show signs typical for Cushing's disease (increased thirst, increased urination, weight gain) though they usually test negative for Cushing's disease. These other signs commonly resolve over time.
An electroretinogram will likely be recommended for your pet in order to evaluate retinal function. This test will confirm or rule-out the diagnosis of SARDS by quantifying how much, if any, retinal function is present.
Some dogs afflicted with SARDS become very anxious and unpredictable, probably due to the exceptional stress of sudden vision loss. However, most dogs will eventually adjust to their blindness and their other senses seem to become more sensitive over time. It is important to keep the home environment as stable as possible, and objects should be kept in consistent locations. Pets should not be left outside unattended unless they are in a confined space such as a yard.
Uveal Melanoma and Melanosis
Increased pigmentation within the iris can be caused by melanoma or melanosis.
Melanoma is a type of tumor, arising from the pigmented cells within the eye. In dogs, these tumors are usually benign, but expansion can lead to secondary glaucoma. In cats, tumors are more likely to spread to other areas of the body. Melanosis is a non-cancerous tissue pigmentation, similar to a skin freckle.
In most cases, the first sign noted is a change in iris color. Additionally, change in the shape of the iris or a raised mass of the iris may be seen. Later in the disease process, the changes may produce a high pressure within the eye (glaucoma), causing redness, cloudiness, squinting or loss of vision and eventually eye enlargement.
A thorough examination of the eye is needed in order to determine if the pigmented areas are flat or raised, and if there are pigmented cells floating in the anterior chamber. The pupil may be dilated to evaluate symmetry of iris dilation. The periphery of the eye (iridocorneal angle) may be evaluated by gonioscopy for involvement. In some cases where melanoma is strongly suspected, evaluation of the lungs and abdominal organs with radiographs and ultrasound is recommended to look for cancer spread. The definitive diagnosis is made by examining the tissue under a microscope, but this is not often done initially because obtaining a tissue sample is an invasive procedure.
For melanosis, examinations at regular and initially frequent intervals are often recommended. Photographs may be taken to document the appearance over time. To differentiate melanosis from melanoma, we look for progressive changes in pigmentation, raised areas of pigmentation and elevated intraocular pressure.
No treatment is required for melanosis, only regular monitoring. Treatment of melanoma depends on stage of the disease and species. Small, focal lesions can be destroyed with laser. Larger or diffuse lesions may necessitate removal of the eye, especially if glaucoma has developed. When the eye is removed, microscopic exam is performed to determine tumor type and likelihood of spread.
The prognosis for melanosis is excellent. There is a change in the appearance of the iris, but there are no risks to systemic health with this condition. Melanomas of the iris have been described to spread to other areas of the body. This is especially true for cats, although early removal of the eye does not always prevent spread of tumor cells. In dogs, most intraocular pigmented tumors do not spread beyond the eye.
Uveitis refers to an inflammation (irritation) of the uvea or middle layer of the eye. The outer layer that encloses the eye is composed of the clear cornea and the white sclera. The innermost layer is the nerve layer or the retina. The middle layer (uvea or uveal tract) is the nutritional layer, rich in blood vessels.
It is made up of:
- the iris (colored portion in the front part of the eye),
- the ciliary body that produces the fluid in the eye and the choroid that provides nutrition to the retina inside the eye.
Clinical signs of uveitis include:
- bleeding into the eye and loss of vision.
Uveitis can result in several eye complications such as cataract formation, scar tissue, glaucoma and damage to the retina.
Although uveitis is a specific diagnosis, the diagnosis in itself does not indicate cause. Unfortunately, uveitis appears similar regardless of cause. That is why diagnostic tests are commonly recommended as part of the uveitis evaluation. In dogs, no cause will be found in about 70% of cases. This is true for about 60% of feline cases. Many of these so-called "idiopathic" uveitis cases are immune-mediated and can be chronic. This is especially true in cats. When the uveitis affects both eyes, the concern increases that the uveitis is due to systemic disease, which is found in about 30% of dogs and 40% of cats. Due to its rich blood supply, the uvea or uveal tract is a natural target for diseases originating in other parts of the body. Signs of these diseases may be seen first in the eye, often before signs develop elsewhere in the body. Systemic causes include cancer and certain unusual types of infections. Infectious causes of concern in cats include Toxoplasmosis, feline infectious peritonitis (FIP, dry form of the disease), FeLV or FIV ("kitty AIDS"), and possibly Bartonella and herpes. Fungal infections can cause uveitis in dogs or cats, though these are usually animals that have lived or traveled outside the Northwest.
Infectious causes in dogs include ehrlichiosis, Rocky Mountain Spotted Fever, Lyme's disease and brucellosis. Trauma and cataracts are other common causes of uveitis in either species.
Medical treatment of uveitis must be aggressive to prevent glaucoma, scarring of the structures inside the eye and to prevent possible blindness. Different medications are used to control the original cause of the uveitis, if known, and to minimize the inflammation itself. The treatment protocol will vary for each patient, but often includes a steroid eye medication to decrease the inflammation, atropine to alleviate the pain (people with uveitis get a tremendous headache!) and possibly medicine to control glaucoma. If caught early and treated diligently and aggressively, uveitis will often resolve without serious consequences.