Conjunctiva

a transparent lubricating mucous membrane that covers the eyeball and the under surface of the eyelid

Conjunctivitis is an inflammation or infection of the conjunctiva. The conjunctiva can become irritated as a result of allergies to pollens, grasses, etc. or from infections caused by viruses, bacteria, or fungi. Conjunctivitis is the most common problem that affects the eyes of cats and dogs.

Feline Conjunctivitis

Conjunctivitis is inflammation of the pink membrane part of the eye, which lines the white part (sclera) and the inner eyelid. The conjunctiva can become quite reddened and swollen in some cats, and often it is just in one eye and not in both. This causes intermittent or constant squinting. It can occur on and off, for months to years. The conjunctivitis may occur without any other eye problems, or the eye may also have a corneal ulcer or erosion (painful open sore on the cornea, which is the “clear windshield” part of the eye), Keratitis (corneal inflammation), and/or uveitis (intraocular inflammation). Corneal involvement and uveitis are often caused by Feline Herpesvirus-1. (FAQ on Feline Conjunctivitis)

Follicular Conjunctivitis

Follicular conjunctivitis (inflammation of the thin membrane that covers the white part of the eye) is often, but not always associated with seasonal allergies.  The conjunctivitis results from exposure to environmental allergens (such as pollens and grasses), rather than to viral or bacterial infections.  Younger dogs, and larger dog breeds less than 2 yrs of age tend to be the most commonly affected. (FAQ on Follicular Conjunctivitis)

Nodular Granulomatous Episcleritis

Nodular granulomatous episcleritis (NGE) is an immune-mediated (inflammatory) disease that affects the sclera, cornea and nictitans.  The condition is diagnosed most commonly in Collies, Cocker Spaniels, and related breeds.  Usually a combination of topical and oral anti-inflammatory and / or immunosuppressant medications is prescribed to treat the condition.  Once the episcleritis is in remission, the medications are slowly tapered over a period of several months to minimize the risk of recurrence.  In severe cases surgical debulking of the nodules with cryotherapy (freezing procedure) may be necessary to induce remission.  (FAQ on Nodular Granulomatous Episcleritis)