Glaucoma / Anterior Chamber
Home / Ophthalmic Pathology / Glaucoma / Anterior Chamber
Anterior Chamber and Trabecular Meshwork
Glaucoma: Yanoff defines as “a syndrome characterized by an elevation of intraocular pressure of sufficient degree or chronicity to produce ocular tissue damage.” Quigley defines as “an optic neuropath associated with characteristic excavation of the optic disc and progressive loss of visual field sensitivity.”
The eye produces (at the ciliary body – nonpigmented ciliary epithelial cells) and drains aqueous fluid (at the trabecular meshwork and canal of Schlemm and to a lesser extent, iris veins and posterior uveoscleral outflow) constantly. The balance of these processes determines intraocular pressure.
Normal trabecular meshwork
11.01 Normal trabecular meshwork. Schwabes line is seen at the termination of descemets membrane. Also seen is the nonpigmented trabecular meshwork, the pigmented area, and the scleral spur.
11.02 Normal trabecular meshwork
11.03 High magnification view of schlems canal and juxtacanalicular tissue.
11.04 Schlemms canal with a draining aqueous vein
Nick’s Tips: www.gonioscopy.org (no affiliation) is an excellent resource for additional information and clinical correlations.
- Derived from neural crest.
- Composed of interconnected collagenous trabeculae (beams) covered by trabecular endothelial cells.
- Located in the notch just anterior to the scleral spur between the cornea and the iris.
- Juxtacanalicular connective tissue forms a porous membrane that acts as the primary barrier to aqueous outflow.
- Gonioscopy of the normal, wide open angle:
- Structures visible (from anterior to posterior)
- Posterior cornea (may have Sampaolesi’s line)
- Schwalbe’s line (site where Descemet’s membrane terminates)
- Trabecular meshwork (non-pigmented)
- Trabecular meshwork (pigmented)
- Scleral spur – longitudinal muscle of ciliary muscle, provides shelf for the trabecular meshwork. Tension on CB pulls open the trabecular meshwork to raise aqueous outflow.
- Ciliary body
- Iris
- Look for synechiae, neovascularization, iris angle, et cetera.
- Structures visible (from anterior to posterior)
Congenital Anomalies
Posterior embryotoxon: thickening and anterior displacement of Schwalbe’s line by thickening and balling of Descemet’s membrane.
11.05 Thick Descemet’s in posterior embryotoxin
11.06 Thick/folded Descemet’s in posterior embryotoxin
Axenfeld-Rieger Syndromes-Mesodermal dysgenesis. (Actually neural crest)
11.07 Axenfeld-Rieger Syndrome looks like posterior embryotoxin with tissue extending onto the iris causing atrophy
- Characterized by strands of iris crossing the trabecular meshwork and inserting into the posterior embryotoxon (the anteriorly displaced Schwalbe’s line)
- 50% risk of glaucoma.
- Often hereditary (AD) – mutations in
- PITX2
- FOXC1
- REIG2
- Rieger Syndrome – bone and dental anomalies including maxillary hypoplasia and anodontia, oligodontia, microdontia, and peg-like incisors.
Peter’s Anomaly
11.08 Peter’s anomaly
11.09 Peter’s anomaly – see posterior embryotoxin, fibers extending to the iris, and loss of central posterior cornea
11.10 Peter’s anomaly – loss of central descemets and endothelium
- Central internal ulcer – non-infectious concavity and defect with absent corneal endothelium, Descemet’s membrane, and posterior stroma.
- Bowman’s layer may be thickened or absent.
- Corneal edema develops due to absent endothelium.
- Crystalline lens may adhere to the cornea in severe cases (keratolenticular adhesion)
- Genes involved in Peter’s anomaly include:
- PAX6
- PITX2
- CYP1B1
- FOXC1
Primary Congential Glaucoma
Nick’s Tips: Haab’s striae are horizontal and associated with glaucoma, Vogt’s striae are vertical and associated with keratoconus. Forceps injury also tends to cause vertical or oblique striae.
- 60% sporadic cases, 40% familial1
- Bilateral and usually autosomal recessive. More common in Middle East and Saudia Arabia2
- Frequently associated with mutations in
- CYP1B1 (Cytochrome P450 1B1)
- LTBP2 (Latent transforming growth factor beta binding protein 2)
- TEK (Tunica interna endothelial cell kinase)
- Signs:1,2 (differential includes nasolacrimal duct obstruction, corneal abrasion, conjunctivitis and uveitis)
- Light sensitivity (photophobia)
- Blepharospasm
- Epiphora (tearing)
- Elevated intraocular pressure (greater than 21 mm Hg)
- Later stages:
- Buphthalmos (enlargement of the eye) in later stages.
- Haab striae (horizontal ruptures of Descement’s membrane) in late stages
- Progressive optic atrophy
- Corneal opacification
- Do not treat children with alpha-2 agonists (like brimonidine) as these can cause apnea and bradycardia.
- Treatment:
- Clear cornea – surgical goniotomy or
- Cloudy cornea
- Trabeculectomy
- Trabeculotomy
- Deep sclerectomy
- If initial surgical management fails, consider
- Glaucoma drainage implants
- Cyclodestruction procedures
- Infantile glaucoma can be associated with the following conditions
- Aniridia
- Anterior segment dysgenesis syndromes such as Peters Plus Syndrome
- Axenfeld-Rieger Anomaly
- Congenital hereditary endothelial dystrophy (CHED)
- Lowe syndrome
- Microcornea
- Neurofibromatosis type 1
- Nance-Horan Syndrome
- Sturge-Weber Syndrome
- Histopathology of primary glaucoma3
- May have Barkan’s membrane covering the trabecular meshwork – the presence of this membrane has not been conclusively demonstrated.
- Trabecular beams are thickened, fewer in number, and compacted.
- Hypoplasia of the trabecular meshwork
- Smooth muscle of the ciliary body was attached to the trabecular meshwork without intervening scleral spur
- Lack of the scleral spur
- Posterior displacement and poor development of the canal of Schlemm without appropriate anatomic relationship with the trabecular meshwork.
- Anterior insertion of the iris
- Hypoplastic iris
- Diffuse ganglion cell loss in the retina
- Cupping of the optic nerve.
11.11 Barkan’s “membrane” in congenital glaucoma is really an abnormal angle
11.12 Maldeveloped angle in Barkan’s membrane
11.13 Glaucomatous optic nerve
11.14 Excavation at the optic nerve
11.15 End stage glaucoma with thinning and loss of the ganglion cell layer of the retina
Degenerations
Iridocorneal Endothelial Syndrome (ICE)
11.16 Essential iris atrophy
11.17 Chandler syndrome
11.18 Iris nevus (Cogan-Reese) syndrome
11.19 Layer of abnormal endothelial cells growing over the angle onto the iris causing descemetization and holes in the iris
11.20 Periphral iridectomy of an iris nevus
11.21 Magnified iris nevus
- Abnormal proliferation of corneal endothelium (+Descemet’s membrane) across the trabecular meshwork.
- Endothelial cells should be unable to proliferate in adulthood, but in ICE syndrome, they lose this inhibition and proliferate and extend across the trabecular meshwork. The abnormal cells are visible on clinical specular microscopy as a two clearly divided population of endothelial cells differing in both size and shape.
- Causes second degree angle closure glaucoma
- Three Syndromes:
- Iris Nevus (Cogan-Reese) syndrome
- Iris covered by endothelium
- Ectopic Descemet’s membrane present on iris surface.
- Chandler Syndrome
- Corneal edema is most prominent feature
- Essential iris atrophy
- Polycoria
- Iris atrophy
- Full thickness iris holes
- Most are young/middle age. Unilateral.
- Iris Nevus (Cogan-Reese) syndrome
Exfoliation syndrome (Pseudoexfoliation)
11.22 Scalloped borders seen in exfoliation syndrome (pseudoexfoliation)
11.23 Stained exfoliated material on the lens capsule appears similar to iron filings
11.24 Exfoliative material clogging the trabecular meshwork
- PAS + fibrils deposited on lens capsule, Zonular fibers, trabecular meshwork, it is, ciliary body, cornea, etc.…
- Fibrillin, gelastin, laminin fibrils
- Coated with hyaluronic acid
- Transillumination defects prominent.
- 10-23% glaucoma
- Associated with HTN, CVA, MI
- Increased risk of zonular dehiscence, during CE
- May occur in patients from many different regions in the world
- Pseudo exfoliation material is produced by all epithelial cells in eye, possible other areas.
- Has an iron filing pattern on lens capsule
- Can see pseudo exfoliative material at pupillary border in pseudophakic patients
- Cataract surgery decreases the risk of glaucoma in pseudoexfoliation.
Phacolytic glaucoma
11.25 Phacolytic glaucoma with injected conjunctiva and a mature cataract
11.26 Macrophages engulf protein, clogging the meshwork in phacolytic glaucoma
11.27 Aspirate of macrophages in phacolytic glaucoma
- Denatured lens protein leaks from hypermature cataract (esp. Morgagnian).
- Characterized by:
- Macrophages full of lens proteins
- Anterior uveitis
- Clogged meshwork.
Trauma
11.28 Angle recession
11.29 Angle recession compared to normal
11.30 Long term sclerotic changes after angle recession
11.31 Long term results of trauma causing angle recession and lens rupture
- Ghost cell glaucoma
- RBCs are tan, rigid, spherical.
- Obstruct trabecular meshwork.
- Occurs after hyphema – note that RBCs may cause acute glaucoma in hyphema as well
- Angle recession: at 180 degrees. 5-10% risk of glaucoma. Tear of ciliary body between longitudinal and circular muscles. Glaucoma may occur years later.
- Cyclodialysis – longitudinal muscle detaches from scleral spur.
- Iridodialysis – iris root detachment.
Pigment Dispersion Syndrome
11.32 Radial transillumination
11.33 Pigment dispersion syndrome with deposition in the meshwork and surface of the cornea
- Pigment and macrophages laden with pigment found in the trabecular meshwork
- Signs include:
- Radial transillumination defects
- Krukenberg spindle (pigment on endothelial surface of the central and inferior cornea
- Pigment in the inferior trabecular meshwork as seen on gonioscopy
- Pigment on lens capsule.
- Most common in moderately myopic, younger, males
- It is presumed that the pigment present originates with iris pigment rubbed off by lens zonules
- Pigment is found both intracellularly and extracellularly
- Iris melanoma can release pigment and melanoma cells clogging the trabecular meshwork. (see uveal melanoma for more discussion). Consider this in the differential diagnosis of pigment dispersion syndrome.
11.34 Secondary open angle glaucoma due to the pigmented cells of uveal melanoma
11.35 Secondary open angle glaucoma caused by malignant melanoma growing from ciliary body into iris root
- Pathology after acute rises in IOP
- Schnabel’s cavernous optic neuropathy
- White splotches within the optic nerve seen on H&E
- Hyaluronic acid influx seen with Alcian blue staining of the optic nerve after acute rises of IOP.
- Schnabel’s cavernous optic neuropathy
11.36 Optic nerve cross section of Schnabel’s optic neuropathy
11.37 Alcian blue staining of hyaluronic acid in Schnabel’s
Glaukomflecken- vacated spaces under lens capsule after acute rises in IOP.
Nick’s Tips: look for history of high IOP and degenerating epithelium and cortical fibers.
- White flecks just beneath the lens capsule
- Seen after episode of very high intraocular pressure
- Focal necrotic lens epithelial cells under capsule
- Degenerated subepithelial cortical material present
11.38 Swollen vacuolated spaces under lens epithelial cells in glaukomflecken
References:
- Lewis, CJ, Hedberg-Buenz A, DeLuca AP, Stone EM, Alward WLM, Fingert JH. Primary congenital and developmental glaucomas. Hum Mol Genet 2017;26(R1):R28-R36.
- Abu-Amero KK, Edward DP. Primary Congenital Glaucoma. Gene Reviews 2017.
- Perry LP, Jakobiec FA, Zakka FR, Walton DS. Newborn primary congenital glaucoma: Histopathologic features of the anterior chamber filtration angle. Journal of American Association for Pediatric Ophthalmology and Strabismus. 2012;16(6):565-568.