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 duration of 4 weeks generally cited as the maximal amount of time for a reasonable prognosis for vision to be considered.