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Diseases of the equine cornea (Proceedings)

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Oct 01, 2008

•Thickness

•< 1mm thick

•Thinnest at center

•0.56 mm

•Exposed Surface

•Epithelium 10-15 cell layers thick

•Stroma

•Bulk of Cornea

•Collagenous fibers (Type 1 and 2)

•Descemet's membrane

•Homogenous membrane of fine collagenous fibers



•"basement membrane"

•Endothelium

•Deepest layer

•Pump's fluid out of cornea

•Deturgescent state

•Nerve Supply

•Ophthalmic branch of Trigeminal (V)

•Naked nerve endings : Stimulation = Extreme Pain

•Located just below the epithelium

•Superficial abrasions : Very Painful

•DEEP STROMA

•Nerves are more sensitive to pressure than to painful stimuli

•Metabolism

•Avascular: How does it get oxygen and metabolites

•Peripherally positioned limbic capillaries

•Aqueous Humor

•Tear Film : Major source for dissolved oxygen

Response to Injury

•Epithelial cell mitosis occurs only in basal layer

•Stem cells at limbus

•After injury cells at wound edge enlarge & loose attachments to BM, slide over defect

•0.6 mm/day

•5-7 days for superficial ulcer to heal

•Six weeks are needed to attach the epithelial cell basement membrane to the stroma

•Initially monolayer of cells, but eventually multilayered sheet will cover wound

•Mitosis resumes after wound closure

•Deep Ulceration

•Stromal Cells

•Do not regenerate

•Replaced by Scar tissue

•Fibroblasts

•Accompany blood vessels

•Visible 3-5 days after injury