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Eye Diseases: WHAT ARE CATARACTS?
A cataract is defined as any opacity (or opacities) of the lens of the eye. Such opacities may be quite small and interfere little with vision, or they may involve the entire lens causing blindness. Cataracts occur because something interferes with the normal function of lens fibers causing them to degenerate. Causes include inflammatory diseases, hereditary factors, aging changes, toxicities, and metabolic diseases such as diabetes mellitus. . . . . MORE
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Eye Diseases: WHAT IS KERATOCONJUNCTIVITIS SICCA (DRY EYE)?
The tear film consists of 3 layers: A superficial lipid (oily) layer which decreases evaporation, a middle aqueous layer which contributes 90% of the tear film, and a deep mucin layer which facilitates spreading of the tears over the cornea.
Keratoconjunctivitis sicca (KCS) occurs whenever there is decreased production of tears or increased evaporation or break-up of the tear film. The problem is most common in dogs but occasionally occurs in cats and horses. Usually the problem arises as a decrease in aqueous tear production which may occur as a result of toxic or inflammatory degeneration of the lacrimal glands (certain drugs, viruses, etc have been incriminated), damage to the innervation of the lacrimal glands, or chronic conjunctivitis. In many cases no specific cause can be identified. When the aqueous tear production decreases, mixing of the oily and mucin layers occurs producing a thick, yellowish, ropy discharge which clings to the eye. Drying of the cornea produces irritation which results in vascularization, pigmentation, and scarring of the cornea. . . . . MORE
View/download KCS/Dry Eye handout
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