When the epithelium is damaged, the fluorescein dye stains the exposed stroma an iridescent green, which highlights the ulcer. The dye does not stain the undamaged epithelium. In other cases it is necessary for the veterinarian to use a special stain (fluorescein dye) to detect corneal damage. Large or deep ulcers may be visible just by looking at the eye. This indicates corneal edema, or swelling of the cornea with fluid as a result of inflammation. If you get a good look at the eye, you may see that the normally clear cornea is cloudy or milky. The cat will resist if you try to look at the eye, so these signs may be all you see. The eye may produce excessive tears that spill over the eyelid and wet the face below the eye. Less commonly, bacterial or viral infections can cause corneal damage.(In addition, bacterial invasion of an already damaged cornea can worsen a corneal ulcer or slow its healing.)Ĭorneal injuries are very painful, so the dog may keep its eye closed and rub the eye with its paw or on the carpet. Irritating chemicals, such as dips and shampoos, can also damage the cornea. Common examples include a blow to the eye, a cat scratch, and rubbing at a painful or itchy eye. The most common cause of a corneal ulcer is trauma. If the descemetocele ruptures, or if the corneal injury was deep enough to damage Descemet's membrane, the fluid inside the eye leaks out and the eyeball may collapse. This structure develops when the fluid in the eye causes the exposed part of Descemet's membrane to bulge through the ulcer, forming a little bubble. A deep ulcer that extends down to Descemet's membrane can result in a descemetocele. Injury that extends through the epithelium and into the stroma is called a corneal ulcer. Injury to the cornea that damages only the epithelium is called a corneal abrasion. Stroma - the layers of cells between the inner and outer membranesĭescemet's membrane - the thin membrane on the inner surface of the cornea The layers are divided into three regions:Įpithelium - the thin membrane on the outer surface of the cornea Although it is clear, the cornea consists of many layers of cells. It is like a pane of glass, being a barrier to the outside while letting light into the eye. The cornea is the clear, glistening dome at the front of the eye. First, a little information about the cornea.
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