Flashcards in BCSC Path Deck (117):
Are dystrophies of the cornea bilateral?
Corneal dystrophies of which layer are most common?
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?
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?
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?
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?
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?
From what cells are trabecular meshwork derived?
From what germ layer is the schlemm canal derived?
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
Is Simple Episcleritis usually associated with antecedent injury or systemic illness?
Is Nodular Episcleritis usually associated with systemic illness?
Yes, particularly rheumatoid arthritis
What is the histologic characterization of Nodular Episcleritis?
Nodules composed of necrobiotic granulomatous inflammatory infiltrate (similar to rheumatoid nodules in subcutaneous tissue)
What are the two patterns of scleritis?
Necrotizing and Non-necrotizing
How can scleritis lead to staphyloma?
Necrotic scleral stroma is resorbed after an episode of scleritis, leaving a thinned scleral remnant. Such areas of thinned sclera are susceptible to staphyloma formation
What is a Scleral Staphyloma?
A scleral staphyloma is an ectasia (outpouching) of the sclera lined internally by uveal tissue. Scleral staphylomas commonly occur at sites of thin or weak sclera.
From which germ layer is the lens derived?
What is the histology of the lens capsule?
The lens capsule is a thick basement membrane elaborated by lens epithelial cells, and is composed primarily of type IV collagen.
Where is the lens capsule the thinnest?
Where are lens epithelial cells located?
A single layer of lens epithelial cells are located anterior to the equator, and more mitotically active lens epithelial cells are present at the equator.
Into what do mitotically active lens epithelial cells differentiate?
What is seen clinically in anterior lenticonus (lentiglobus)?
An "oil-droplet" red reflex
What type of endophthalmitis does P acnes generally cause?
a chronic endophathlmitis 2 months to 2 years after cataract surgery. Onset may coincide with YAG capsulotomy (which may release sequestered organisms)
What is phacoantigenic uveitis?
Inflammatory reaction to lens antigens released due to accidental or surgical trauma to the lens
What are two elements that commonly deposit in the lens capsule?
Copper (chalcosis) and Silver (argyrosis)
What is a duplication cataract?
A lens opacity consisting of a second lens capsule (secreted by lens epithelial cells) on underneath an anterior subcapsular fibrous plaque (which forms in response to inflammation)
What are common causes of a posterior subcapsular cataract?
Prolonged corticosteroid use, DM, intraocular inflammation, smoking, ionizing radiation
How does a posterior subcapsular cataract (PSC) form?
Epithelial disarray occurs at the equator, leading to posterior migration of lens epithelial cells. These migrating epithelial cells then swell to 5-6 times their normal size, at which point they are referred to as Bladder Cells of Wedl. These cells cause visual impairment if located in the visual axis.
What are Elschnig pearls?
Globules of abnormally proliferating lens epithelial cells that can lead to capsular opacification.
Are there any histological differences between Bladder Cells of Wedl and the cells comprising Elschnig pearls?
No, Bladder Cells of Wedl and Elschnig pearls demonstrate histologically identical cells!
What are morgagnian globules?
Eosinophilic globules in slitlike spaces between cortical lens fibers that form due to lens cortex degeneration
What is a morgagnian cataract?
A morgagnian cataract involves complete liquefaction of the lens cortex, with subsequent falling of the lens nucelus out of the visual axis. The lens capsule subsequently wrinkles, worsening the visual impairment.
What is the theorized etiology of nuclear hardening?
Compression due to continued production of lens fibers in adult life.
What is the theorized etiology of nuclear discoloration?
Nuclear discoloration is poorly understood, but appears to involve accumulation of urochrome pigment
Are there any known tumors of the human lens?
What is the average volume of vitreous in the adult?
What is the composition of vitreous?
99% water, type II collagen, type IX collagen, GAGs, soluble proteins, glycoproteins
What is the outer surface of the vitreous cortex called?
The hyaloid face
How is the vitreous connected to the lens capsule?
The anterior hyaloid face is connected to the posterior capsule via the hyaloideocapsular ligament, which weakens with age.
Where are the firm attachments of the vitreous?
1) Vitreous base, 2) margins of optic nerve head, 3) circualr area around fovea, 4) edges of vitreoretinal degeneration, such as lattice degeneration
What is the vitreous base?
A 360 degree band that straddles the ora serrata. The vitreous attaches firmly to the vitreous base
How many stages of vitreous development are there?
What comprises the primary vitreous?
1) fibrillar material; 2) mesenchymal cells; 3) vascular components, including the hyaloid artery, vasa hyaloidea propria, and tunica vasculosa lentis
What is the secondary vitreous?
The main portion of the vitreous in the postnatal and adult eye
What is the tertiary vitreous?
The lens zonular fibers
What is persistent fetal vasculature?
The presence of remnants of components of the primary vitreous. PFV is usually uniltateral
What is a Bergmeister papilla
A veil-like structure of fingerlike projection extending anteriorly from the surface of the optic nerve head. This is a remnant of the posterior posrtion of the hyaloid artery.
What is a Mittendorf dot?
A focal lens opacity at the site of the previous attachment of the hyaloid artery to the tunica vasculosa lentis, usually located inferonasal to the center of the lens.
Is the vitreous avascular?
Is the vitreous acellular?
No, but there are very few cells, called hyalocytes, in the vitreous.
What are the layers of the retina [and structures underneath in brackets]?
ILM, NFL, GCL, IPL, INL, (MLM), OPL, ONL, XLM, IS, OS, [ RPE, Bruch, Chorioid ]
What is the clinical characterization of CHRPE?
CHRPE involves a flat, dark black lesion 3-10mm in diameter. A CHRPE lesion may have central lacunae and a peripheral zone of less dense pigmentation.
Is the nerve fiber layer normally myelinated?
No, myelination of the NFL can lead to scotomata
Where is the watershed zone between the retinal and chroidal arterial supplies?
The watershed zone is in the INL
What is the histologic definition of the macula?
The portion of the retina in which the ganglion cell layer (GCL) is greater than 1 cell thick, plus the fovea (where the GCL is absent).
Are the inner cellular layers present in the fovea?
No, the inner cellular layers (and possibly part of the OPL) are not prsent in the fovea, which contributes to the foveal "pit" appearance.
What are Typical Peripheral Cystoid Degeneration (TPCD) and Reticular Peripheral Cystoid Degeneration (RPCD)?
Both terms refer to the development of cystoid spaces in the peripheral retina, which can lead to retinoschisis. TPCD is present in nearly all people over 20 years old. RPCD is less common.
In which retinal layer does TPCD occur?
In which retinal layer does RPCD occur?
In what percent of the population is lattice degeneration found?
What percent of rhegmatogenous retinal detachments involve lattice degeneration?
What are the histopathologic features of lattice degeneration?
1) ILM discontinuity, 2) overlying pocket of liquefied vitreous, 3) sclerosis of local retinal vesses while they remain patent, 4) adherence of vitreous to margins of lesion, 5) atrophy of the inner layers of the retina
What produces the lattice pattern in lattice degeneration?
Sclerotic (but patent) retinal vessels that appear white and create a criss-cross pattern
What is the cause of retinal breaks associated with lattice?
Vitreous adhesion at the margins of a lattice lesion. Atrophy of the inner layers of the retina is thought to NOT contribute.
How long of an interruption in blood supply is required for retinal neurons to die?
90 minutes. After 90 minutes of oxygen deprivation, retinal neurons become pyknotic (chromatin condenses) and the cells are phagocytosed.
Do the neuronal cells of the retina have capacity for regeneration after ischemic damage?
What does the Outer Nuclear Layer (ONL) contain?
What does the Inner Nuclear Layer (INL) contain?
3 types of cells (Bipolar, Horizontal, and Amacrine) that receive data from photoreceptors, perform computations, and transmit data to retinal ganglion cells (in the GCL)
What do cotton wool spots represent?
Localized accumulation of axoplasmic material in the nerve fibers (in the NFL) of ischemically damaged retinal ganglion cells.
Exudate accumulating in which layer of the retina results in a star pattern in the macula?
The Outer Plexiform Layer (OPL), due to the orientation of the nerve fibers in the OPL
How does chronic edema result in hard exudates?
Lipid and protein collect in the extracellular space. As edema becomes chronic, the water component of the exudate is more efficiently removed, resulting in "hard" exudates.
In which retinal layer do flame-shaped hemorrhages occur?
The Nerve Fiber Layer (NFL) due to the shape and orientation of the nerve fibuers in the NFL.
In which retinal layer(s) do dot and blot hemorrhages occur?
nuclear or inner plexiform layers
What shape do retinal hemorrhages in the sub-hyaloid or sub-ILM spaces take on?
A boat shape
What are Intraretinal Microvascular Abnormalities (IRMAs)?
Dilated, irregular vascular channels occuring next to regions where capillaries have become acellular secondary to vascular occlusion
What are intraretinal microaneurysms?
Fusiform or saccular outpouchings of the retinal capillaries. Microaneurysms are best seen with FA.
What are the 3 sites of firm attachment between the uveal tract and sclera?
1) Scleral spur, 2) exit points of vortex veins, 3) optic nerve
What is the embryologic origin of the uveal tract?
Mesoderm and Neural crest
What are the 5 layers of the iris?
From anterior to posterior: 1) Anterior border layer, 2) Stroma, 3) Muscular layer, 4) Anterior pigment epithelium, 5) Posterior pigment epithelium
What are the two parts of the ciliary body?
The 1) Pars plicata and 2) Pars plana