Definition:

Pannus is inflammation of the cornea causing opacification and, eventually, visual impairment from the infiltration of blood vessels and pigment. 

Anatomy/Physiology:

Blood vessels, granulation tissue (fibrovascular tissue) and white blood cells (lymphocytes and plasma cells) invade the superficial corneal stroma. 

Clinical Signs:

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. 

Causes:

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.

Examination:

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.

Treatment:

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.

Prognosis:

The condition can be controlled but not cured.  Life-long topical medications are usually needed. 

Revised 4/20/10