Terms & definitions Flashcards
Inflammatory pannus
Destruction of Bowman’s membrane (trachoma) with peripheral and growth of sunepithelial fibrovascular tissue
Degenerative pannus
Bowman’s membrane remains intact; may contain fatty plaque deposits (chronic edema)
-most commonly due to contact lens wear
What is a fibrous downgrowth or ingrowth?
In corneal graft failure, there is often associated bullous keratopathy.
And half of these cases, a fibrous retrocorneal membrane is visualized.
If the membrane is thick and contiguous with the corneal stroma in the region of an incision it is called fibrous downgrowth.
What is an epithelial down growth or ingrowth?
A graft fails because of growth of surface epithelium through a parlay a post wound and onto the retro corneal surface.
What are the risk factors for ingrowth?
What is the prognosis is ingrowth occurs?
Main risk factor for fibrous or epithelium ingrowth is multiple prior penetrating keratoplasties.
Both types of ingrowth are very poor prognostic sign for graft survival and for general ocular health as they are associated with secondary angle closure glaucoma.
Corneal dystropies
Inherited genetic disorders usually defective enzyme or structural protein.
AD except macular, type 3 lattice and nystagmus associated form of CHED which are AR
PPMD
Posterior polymorphous corneal dystrophy
Endothelium behaves like epithelium, forming multiple layers with occasional migration of cells into angle causing glaucoma (15%)
What is the pathophysiology of PPMD
pathogenesis of PPMD is attributed to an abnormal developmental differentiation of the endothelial cells. Histologic studies have shown that the morphology of the endothelial cell layer resemble those of the epithelium (Fig. 5a). These multilayered epithelial-like cells are keratinized (Fig. 5b, c), connected by well-developed desmosomes, and appear to have microvilli when examined under scanning electron microscopy [7, 8]. Moreover, these cells can migrate over the trabecular meshwork and iris, causing extensive peripheral synechiae and glaucoma
Clinical findings in PPMD?
Isolated group vesicles, geographically shaped discrete grade lesions, broadband with scalloped edges
Variable amounts of stromal edema, corectopia, broad iridocorneal adhesions.
Microscopic pathological findings in posterior polymorphous corneal dystrophy?
Irregular labs were vacuoles at level of descemet’s surrounded by great opacification
Thickened descemet’s, Abnormal endothelial cells (resemble epithelial cells; contain keratin, microvilli, desmosomes)
Epithelial downgrowth.
What is it?
When does it occur?
Surface epithelium grows through wound into Eye covering anterior segment structures.
Can occur following almost any interocular surgery; increased risk with complicated surgery associated with hemorrhage, inflammation, vitreous loss, or incarcerated tissue.
Risks of epithelial down growth?
Epithelium can cover the endothelium (leading to edema) and the angle (resulting in glaucoma) ; Contact information by healthy endothelium may inhibit this.
Pathology of epithelial down growth?
Multilayered nonkeratinized squamous epithelium
PAS stands conjunctival goblet cells (differentiate between corneal and conjunctival epithelium)
Fibrous in growth
Fibrous proliferation through wound into AC
Less progressive and destructive than epithelial downgrowth
Fibroblasts originate from episclera or corneal stroma
Iridocorneal endothelial syndrome
Spectrum of acquired unilateral abnormalities of the corneal endothelium, anterior chamber angle, and Iris typically affecting young to middle aged adults. Unilateral.
I: Iris nevus (Cogan-Reese) syndrome
C: Chandler syndrome
E: essential iris atrophy
Pathology of ICE syndrome?
Epithelial like metaplasia and abnormal proliferation of the corneal endothelium.
Abnormal endothelial cells migrate over the anterior chamber angle, leading to peripheral anterior synechiae (PAS) formation and subsequent secondary angle closure glaucoma in approximately half of patients with this condition.
Pannus
Degeneration- Peripheral ingrowth of subepithelial fibrovascular tissue, usually superiorly.
Inflammatory or degenerative
Define ICE syndrome
Iridocorneal Endothelial (ICE) Syndrome
Non-hereditary, progressive abnormality of corneal endothelium. Growth of endothelium and descemet’s membrane over trabecular meshwork and onto Iris.
Abnormal corneal endothelium grows across angle and Iris, producing membrane that obstructs trabecular meshwork, distorts Iris, and may contract around Iris
Unilateral, mostly woman, middle-age
Cogan Reese syndrome
Iris nevus syndrome: flattening and effacement of iris stroma, pigmented iris nodules (pseudonevi) composed of normal Iris cells that are bunched up from the overlying membrane, corectopia, ectropion uveae.
Chandlers syndrome
Corneal edema often with normal IOP, mild or no iris changes (minimal corectopia,Iris atrophy, peripheral anterior synechiae)
Essential Iris atrophy
Proliferating endothelium produces broad PAS, corectopia, ectropion uvea, and Iris holes (stretch holes - areas away from maximal pull of the endothelium membrane is stretched so thin that holes develop, and melting holes – holes in areas without Iris thinning due to Iris ischemia)
Oncocytoma
Benign proliferation of apocrine or accessory lacrimal gland epithelium, and adenoma.
Typically arises in car uncle
Most commonly occurs an elderly woman
Clinically appears as tan to reddish vascularized nodule.
Histology of Oncocytoma
arises from metaplasia of ductile and Acinar cells of accessory lacrimal glands –Proliferating epithelial cells similar in appearance to apocrine (Gland of Moll) epithelium around gland like spaces.
Polyhedral cells arranged in nests, cords, or sheets.
Because of the cystic appearance of the spaces, the term Apocrine cystadenoma is also used.
Epithelial cells exhibit distinctive eosinophilic cytoplasm, “oxyphilic cystadenoma” eosinophilic cytoplasm correlates with abundance of mitochondria.
Syringoma
Common benign lesion of the lower eyelid.
Typically manifests as multiple tiny papules.
Result from malformation of eccrine sweat gland ducts. Benign proliferation of eccrine ductal structures.
Histology of Syringoma
Consist of multiple, comma-shaped or round ductules lined with a double layer of epithelium (“tadpoles”) and containing a central lumen, often with secretory material.
