BCSC Path Flashcards
Are dystrophies of the cornea bilateral?
Yes
Corneal dystrophies of which layer are most common?
Epithelium
What do patients with epithelial dystrophy often present with?
Symptoms of recurrent erosion syndrome
How do dots form in map-dot-fingerprint dystrophy?
Epithelial basement membrane overgrows, with redundancies forming. These redundancies grow to encricle intraepithelial cells. As the encircled cells degenerate, no replacement can occur, leaving cystoid spaces referred to as dots.
What are the common stromal dystrophies?
4 main types: Macular, Granular, Lattice, Avellino
What is the inheritance of macular corneal dystrophy?
autosomal recessive
How is macular dystrophy characterized clinically?
Poorly defined stromal lesions (focal opacities) with hazy intervening stroma
What is deposited in the corneal stroma in macular dystrophy?
Mucopolysaccharide (MPS)
What region (not layer) of the cornea does macular dystrophy affect?
The whole corneal stroma
What region (not layer) of the cornea does granular dystrophy affect?
The central corneal stroma
What is deposited in the corneal stroma in granular dystrophy?
Hyaline material
How is granular dystrophy characterized clinically?
Sharply defined lesions with clear intervening stroma
What region (not layer) of the cornea does lattice dystrophy affect?
The central corneal stroma
How is lattice dystrophy characterized clinically?
Refractile lines with hazy intervening stroma
What is deposited in the corneal stroma in lattice dystrophy?
Amyloid
What is a mnemonic for stromal dystrophies and their deposited materials?
Marilyn Monroe Always Gets Her Man in LA County – Macular, MPS, Alcian blue stain; Granular, Hyaline, Masson trichrome stain; Lattice, Amyloid, Congo red stain
How is Avellino dystrophy characterized clinically?
It has features of both Granular and Lattice dystrophy.
What are corneal guttae?
Guttae are anvil-shaped excrescences of Descemet membrane, which may protrude into the anterior chamber or be buried within a thickened Descemet membrane.
Do guttae imply corneal deompensation?
No, guttae may be recognized in early childhood, long before corneal decompensation occurs
What is the average depth of the anterior chamber?
3.5mm
From what cells are trabecular meshwork derived?
neural crest
From what germ layer is the schlemm canal derived?
mesoderm
What histologic feature does Schwalbe line represent clinically?
the location of termination of Descemet membrane
What is the pathogenesis of primary congenital glaucoma?
arrested development of the anterior chamber angle structures – embryonic conformation, with anterior insertion of irirs root, poorly developed scleral spur, mesenchymal tissue in the angle
What are the anterior segment dysgenesis syndromes?
Axenfeld-Rieger, Peters anomaly, posterior keratoconus,and iridoschisis
What is posterior embryotoxon?
Posterior embryotoxon is a thickened and anteriorly displaced Schwalbe line (termination of Descemet membrane) – it may present as a nodular prominence
What is a mnemonic for the iridocorneal endothelial syndromes?
ICE – Iris nevus syndrome (Cogan-Reese syndrome), Chandler syndrome, Essential iris atrophy
What are the iridocorneal endothelial syndromes?
The iridocorneal endothelial syndromes are a spectrum of acquired unilateral abnormalities of the 1) corneal endothelium, 2) anterior chamber angle, and 3) iris. They typically affect young to middle-aged adults.
What are the features common to all of the iridocorneal endothelial (ICE) syndromes?
1) Epithelial-like metaplasia of the endothelium, 2) abnormal proliferation of the endothelium
What are the “nevi” in iris nevus syndrome?
Pieces of iris stroma pinched off by a migrating membrane composed of epithelial-like metaplastic endothelial cells.
What do migrating abnormal epithelial cells deposit on the iris in ICE syndromes?
a thin membrane that is PAS-positive and analogous to Descemet membrane
What is the clinical characterization of Exfoliation Syndrome (or Pseudoexfoliation)?
Exfoliation syndrome is characterized by the production and progressive accumulation of fibrillar material in tissues throughout the anterior segment (and viscera)
What is the pathogenesis of PXF?
stress-induced elastosis associated with excessive production and abnormal aggregation of elastic fiber components
What is true exfoliation?
Splitting of lens capsule induced by infrared radiation (as encountered by glass-blowers)
What is the clinical characterization of Phacolytic glaucoma?
Secondary glaucoma due to engorgement of the TM by proteinaceous lens material (and macrophages containing said lens material) that has leaked through an intact but permeable lens capsule associated with a hypermature cataract.
What is a ghost red blood cell?
A spherical, rigid RBC in which the hemoglobin has degenerated and is present as small globules called Heinz bodies
What is the pathogenesis of ghost cell glaucoma?
Trauma can lead to blood in the AC. Hemoglobin degeneration leads to ghost cell formation. Ghost cells clog the TM due to their spherical shape and rigidity.
How is ghost cell glaucoma different from hemolytic glaucoma?
While both involve RBCs in the AC, hemolytic glaucoma involves blocking of the TM by macrophages containing RBC breakdown products (hemosiderin and hemoglobin), not RBCs (in ghost cell form) themselves
What is the supposed mechanism of pigment dispersion in pigment dispersion glaucoma?
Mechanical rubbing off of iris pigment epithelium through contact with lens zonular fibers
From which cells is sclera derived?
Neural crest cells
What are the three layers of the sclera?
1) Episclera, 2) Stroma, 3) Lamina fusca
What happens to the sclera at the exit of the optic nerve?
The outer 2/3s of the sclera merges with the dura of the optic nerve and the inner 1/3 becomes the lamina cribrosa
What is the episclera?
The episclera is a thin, loose fibrovascular tissue covering the outer surface of the scleral stroma
What penetrates the scleral stroma?
1) Anteriorly – anterior ciliary arteries/veins and long posteiror ciliary nerves; 2) Equatorially – vortex veins; 3) Posteriorly – posterior ciliary arteries and nerves
What is the lamina fusca?
A delicate, pigmented fibrovascular tissue that loosely binds the uvea to the sclera.
Of what type of collagen is the scerlal stroma composed?
Type I collagen