Ординатура / Офтальмология / Английские материалы / Ocular Pathology_6th edition_Yanoff, Sassani_2009

The site or sites of impaired outflow may vary from eye to eye. The major obstruction may lie near the entrance to the meshwork, in the meshwork, near the efferent vessels of the drainage angle, or any combination thereof. Congenital glaucoma, therefore, will most probably be shown to have a number of causes. For example, a case of congenital glaucoma associated with the chromosomal defect of deletion of the short arm of the 10th chromosome (10p–) showed aberrant trabecular pillars* extending from the iris root toward Schwalbe’s line. Also, as mentioned earlier, a form of autosomal-dominant juvenile glaucoma has been mapped to the long arm of chromosome 1 (1q21–q31).

III.Associated diseases and conditions

A.Iris anomalies (see pp. 334–338 in Chapter 9)

1.Hypoplasia of the iris (“aniridia”) and iris coloboma may be associated with congenital glaucoma.

a.The PAX6 point mutation defect (1630A > T) has been associated with some cases of aniridia.

b.Aniridia may be found in Brachmann–de Lange syndrome, which may also include conjunctivitis, blepharitis, microcornea, and corectopia.

B.Axenfeld’s anomaly and Rieger’s syndrome (see pp. 263 in Chapter 8)

C.Peters’ anomaly (see p. 260 in Chapter 8, and p. 45 in

Chapter 2)

1.Peters’ anomaly and primary congenital glaucoma may share a common molecular pathophysiology.

Both of these disorders can be associated with mutation in the cytochrome P4501B1 (CYP1B1) gene.

D.Phakomatoses

1.Sturge–Weber syndrome (see pp. 30–31 in Chapter 2)

a.Phakomatosis pigmentovascularis (PPV) types II A and B are associated with melanosis bulbi and glaucoma. Ectodermal and mesodermal migration disorders have been postulated to be involved in the pathogenesis of this disorder.

PPV II B is also associated with iris mamillations, Sturge–Weber syndrome, hemifacial, and hemicorporal, or limb hypertrophy without venous insu ciency.

2.Neurofibromatosis (see pp. 31–34 in Chapter 2)

E.Lowe’s syndrome (see p. 367 in Chapter 10)

F.Pierre Robin syndrome

1.Pierre Robin syndrome consists of hypoplasia of the mandible, glossoptosis, cleft palate, and ocular anomalies.

2.Ocular anomalies include glaucoma, high myopia, cataract, neural retinal detachment, and microphthalmos.

G.Rubella (see pp. 43–44 in Chapter 2)

H.Marfan’s syndrome (see pp. 385–387 in Chapter 10)

*Trabecular pillars are distinguished from iris processes by their collagenous core. Iris processes, which are extensions of the iris anterior-border layer, have no collagenous core.

I.Homocystinuria (see p. 385 in Chapter 10)

J.Microcornea (see p. 257 in Chapter 8)

K.Spherophakia (see p. 387 in Chapter 10)

L.Chromosomal abnormalities (e.g., trisomy 13; see pp.

38–39 in Chapter 2)

M.Persistent hyperplastic primary vitreous (see p. 747 in Chapter 18)

N.Retinopathy of prematurity (see p. 748 in Chapter 18)

O.Retinoblastoma (see p. 733 in Chapter 18)

P.Juvenile xanthogranuloma (see p. 343 in Chapter 9) IV. Secondary histologic ocular e ects in young eyes (<10

years of age)

Q.Hennekam syndrome, which includes lymphedema, lymphangiectasis, and developmental delay.

Other associated findings are dental anomalies, hearing loss, and renal anomalies.

R.Nail–patella syndrome is characterized by dysplasia of the nails, patellar aplasia or hypoplasia, iliac horns, dysplasia of the elbows, and frequently glaucoma and progressive nephropathy.

The underlying gene involved is LMX1B, which is a LIM-homeodomain transcription factor. The gene is located at 9q34.

S.Congenital glaucoma can accompany Marshall–Smith syndrome, which is characterized by orofacial dysmorphism, failure to thrive, and accelerated osseous maturation.

T.Subtelomeric deletion of chromosome 6p results in a syndrome characterized by ptosis, posterior embryotoxin, optic nerve abnormalities, mild glaucoma, Dandy–Walker malformation, hydrocephalus, atrial septal defect, patent ductus arteriosus, and mild mental retardation. This syndrome phenotypically overlaps

Ritscher–Schinzel [or craniocerebellocardiac (3C) syndrome].

U.A possible new autosomal-recessive syndrome phenotypically resembles Ivemark syndrome (hepatorenal– pancreatic syndrome) and is characterized by neonatal diabetes mellitus, congenital hypothyroidism, hepatic

fibrosis, polycystic kidneys, and congenital glaucoma.

V.Neurofibromatosis type 1 should be excluded in newborns with unilateral congenital glaucoma.

W.Subepithelial amyloid deposits, in a recessive form of congenital hereditary endothelial dystrophy, can be associated with congenital glaucoma.

X.Congenital glaucoma has occurred in a 28-year-old man with trisomy 7q34-qter and monosomy 15q26.3- qter caused by a paternal balanced chromosomal translocation t(7;15) (q34;q26.3). The patient had some features of the Silver–Russell syndrome, including short stature of prenatal onset, triangular face, clinodactyly of the fifth fingers, and body asymmetry. One copy of the insulin-like growth factor-1 receptor gene (IGF1R) at

15q25–q26 was deleted, which suggested a possible role

for IGF1R in the Silver–Russell syndrome.

IV. Secondary histologic ocular e ects in young eyes (<10 years of age)

A.Buphthalmos (“large eye”) is caused by an enlargement, stretching, and thinning of the coats of the eye,

especially marked in the anterior segment, resulting in a deep anterior chamber (Fig. 16.5).

Subluxated lenses may develop in these eyes.

B.Ruptures of Descemet’s membrane (Haab’s striae) may be found in the enlarged corneas (Fig. 16.6), are usually horizontal in the central cornea but concentric toward the limbus, mainly in the lower half, and are often associated with corneal edema.

Ruptures of Descemet’s membrane secondary to birth trauma tend to be unilateral, most often in the left eye (most common fetal presentation is left occiput anterior), and usually run in a diagonal direction across the central cornea.

C.The limbal region becomes stretched and thin, with a resultant limbal ectasia (see Fig. 16.5).

When the limbal ectasia is lined by uvea (e.g., with peripheral anterior synechiae), it is called a limbal staphyloma (see Fig. 16.5). When it extends posteriorly to involve the sclera over the ciliary body, it is called an intercalary staphyloma.

D.Fibrosis of the iris root and trabecular meshwork is a late manifestation, as is disappearance of Schlemm’s canal.

E.Continued high IOP may cause atrophy of the ciliary body, choroid, and retina, cupping of the optic disc (see Fig. 16.5), and atrophy of the optic nerve.

Cupping of the optic nerve head secondary to glaucoma develops more rapidly in infant eyes than in adult eyes. Unlike in the adult eye, however, cupping in the infant eye is often reversible when the IOP normalizes. Restoration of a normal cup is most rare with glaucomatous cupping in adults.

Primary Glaucoma (Closedand Open-Angle)

I.The classification of the various forms of glaucoma depends on the clinical examination of the anterior-chamber angle by gonioscopy. It is important that the clinician be able to correlate the clinical findings with their histologic counterparts.

II.Optical coherence tomography and ultrasound biomicroscopy can be utilized to evaluate the anatomic configuration of the anterior-chamber angle and adjacent structures for the classification of the pathophysiology of the glaucomas.

Primary openand closed-angle glaucoma occur more often in diabetic patients than in nondiabetic subjects.

III.Closed-angle (narrow-angle; angle closure; acute congestive) glaucoma (Figs 16.7 and 16.8)

A.In anatomically predisposed eyes, primary closed-angle glaucoma develops.

1.The surface of the peripheral iris is close to the inner surface of the trabecular meshwork, causing a narrow or shallow anterior-chamber angle.

Plateau iris configuration is a much rarer cause of closedangle glaucoma than is the typical narrow anteriorchamber angle configuration. In the former condition, closed-angle glaucoma occurs, but direct examination with a slit lamp shows a normal-depth central anterior chamber, and a flat iris plane except at the extreme periphery. A vertical section through the iris displays a “hockey-stick” configuration to the iris contour. Gonioscopic examination, during the acute glaucomatous

A

C

attack, shows a closed anterior-chamber angle. Rarely, multiple ciliary body cysts can cause a plateau iris configuration to the anterior-chamber angle.

2.Small, hypermetropic eyes are especially vulnerable to angle closure.

A founder gene e ect is probably related to two families of the Faroe Islands with hereditary high hyperopia, angle closure glaucoma, uveal e usion, cataract, esotropia, and amblyopia.

Closed-angle glaucoma may be a prominent feature of the oculodentodigital dysplasia (ODDD) syndrome, associated with microcornea, and iris atrophy. It is a rare inherited disorder that impacts the development of the face, teeth, and limbs including narrow nose, hypoplastic alae nasi, anteverted nostrils, syndactyly, and hypoplasia and yellowing of the dental enamel. Other less common findings are intracranial calcification, and conductive deafness secondary to recurrent otitis media. This syndrome can be associated with a mutation (P59H) in the GJ1A gene. It can have an auto- somal-recessive inheritance.

B

Fig. 16.7 Closed-angle glaucoma. A, Patient complained of pain, photophobia, and seeing halos around lights. Right eye shows a semidilated pupil and ciliary injection. B, Histologic section shows peripheral iris surface compressing trabecular meshwork. C, Histologic section of another case shows that eyes prone to acute attacks have a characteristic “crowded” anterior segment.

3.The lens is normal-sized or large.

If the lens becomes large enough (e.g., a swollen, intumescent lens), it may push the iris diaphragm anteriorly so that an angle closure can result even though the anteriorchamber angle had been of normal or average depth.

4.Closed-angle glaucoma is usually a disorder a ecting older individuals; however, it may be found even in individuals 40 years of age and younger.The most common causes (in decreasing order of frequency) in this age group are plateau iris syndrome, iridociliary cysts, retinopathy of prematurity, uveitis, isolated nanophthamlos, relative pupillary block, and Weil–Marchesani syndrome.

B.The trabecular meshwork is normal before an initial attack of acute primary closed-angle glaucoma. After repeated attacks (often at subclinical levels), the stillopen anterior-chamber angle may become damaged

(fibrotic) and, therefore, may simulate chronic simple (open-angle) glaucoma. Pigment accumulation within trabecular cells and loss of trabecular endothelial cells are also common findings following angle closure.

C.A sudden rise in IOP results from the peripheral iris being in apposition to the trabecular meshwork from the pupillary-block mechanisms except in the plateau iris syndrome, which in its pure form, does not involve pupillary block.

The association of typical acute closed-angle glaucoma with increasing age is due, in part, to progressive pupillary block from the increase in lens size as it adds layers of lens fibers over time.

Malignant glaucoma is a rare postoperative complication that follows ocular surgery to control glaucoma (or even after cataract surgery) in eyes that have shallow anterior chambers, often chronic angle closure, and usually peripheral anterior synechiae. Miotics tend to aggravate the condition and, rarely, may precipitate malignant glaucoma even without previous surgery. The condition results from misdirection of aqueous into the posterior segment of the globe, thereby shifting the iris lens diaphragm anteriorly and resulting in angle closure.

D.Histology

1.Segmental iris atrophy

a.Swelling of the iris root and occlusion of the greater arterial circle of the iris or its branches result in occlusion of the arterial supply to the iris stroma and subsequent necrosis.

b.Segmental iris atrophy is usually seen in the upper half of the iris in a sector configuration.

Segmental iris atrophy following closed-angle glaucoma resembles that of herpes zoster iritis. Iris atrophy can also be seen in pseudoexfoliation syndrome and after trauma. The atrophy may be extreme, resulting in a through-and-through iris hole, thereby curing the acute attack of glaucoma.

c.Histologically, there is marked atrophy of the iris stromal layer and, often, of iris pigment epithelium.

2.Irregular pupil results from necrosis of the dilator and sphincter muscles.

b.Histologically, segments of the dilator muscle or its entire length are absent.

c.The sphincter muscle shows varying degrees of atrophy.

3.Glaukomflecken (cataracta disseminata subcapsularis glaukomatosa; see Fig. 16.8)

a.Glaukomflecken probably results from interference with the normal metabolism of the anterior lens cells owing to a stagnation of aqueous humor that contains toxic products of necrosis, or from foci of pressure necrosis (see p. 374 in

Chapter 10).

b.Anterior subcapsular, multiple, tiny gray-white lenticular opacities are seen.

c.Histologically, small areas of epithelial cell necrosis together with tiny adjacent areas of subcapsular cortical degeneration are found.

4.Optic disc edema

a.The nerve fibers in the optic nerve are more susceptible to an acute rise in IOP than are the retinal ganglion cells (RGC).

b.Irreversible vision impairment after an acute attack is mainly caused by optic nerve damage.

Optic disc edema occurs early, probably from temporary obstruction of the venous return at the nerve head caused by the abrupt increase in IOP. If the associated corneal edema is cleared with glycerol during an acute attack, the optic disc edema can be seen ophthalmoscopically in many cases.

c.Histology (see Fig. 13.7B)

5.Neovascularization of iris

a.Neovascularization of iris (clinical rubeosis iridis) is usually secondary to a central retinal vein or artery thrombosis caused by elevated

IOP during the acute attack.

b.Histologically, fibrovascular tissue is found in the anterior-chamber angle and on the anterior surface of the iris.

Familial amyloidotic polyneuropathy type I (Met 30) has presented with neovascular glaucoma.

E.Failure to reverse the initial attack of angle closure can result in chronic angle closure glaucoma.

1.This entity can be confused clinically with chronic open-angle glaucoma unless careful gonioscopy is performed routinely on all suspected cases of glaucoma.

a.Chronic angle-closure glaucoma is associated with the necessity of continued treatment and subsequent procedures even in the presence of a patent iridotomy.

2.Histology

a.There is disorganization of the trabecular architecture, narrowing or loss of trabecular spaces, scarring of the trabecular beams, trabecular

endothelial cell loss, deposition of banded fibrillar material, and melanin pigment deposition.

IV. Chronic open-angle (chronic simple) glaucoma (POAG)

(Figs 16.9 and 16.10)

A.The angle appears normal gonioscopically.

B.The site or sites of resistance to aqueous humor outflow lie within the structures of the drainage angle of the anterior chamber.

Widespread belief exists that the major site of obstruction lies near Schlemm’s canal, but the belief has not been well supported by either experimental or histologic evidence.

C.The condition is most often bilateral.

1.Glaucoma may develop in one eye months to years before the fellow eye.

Patients who have POAG show a significantly higher prevalence of splinter hemorrhages on the optic nerve than do patients who do not have glaucoma. These splinter hemorrhages are associated with an increased incidence of field defects. Disc hemorrhages in glaucomatous or glaucoma suspect eyes are often associated with progressive changes of the optic nerves and of the visual fields.

2.One eye may be more severely a ected than the other eye.

a.Open-angle glaucoma with dilated episcleral vessels may be seen unilaterally in orbital and lid hemangioma (Sturge–Weber syndrome), or bilaterally in carotid cavernous fistula, familial cases, or idiopathic cases.

b.Unilateral open-angle glaucoma may occur in association with lid thickening caused by neurofibromatosis.

D.Prevalence (see earlier, section Introduction)

E.Heredity and genetics

1.In most cases, the condition is probably inherited as an autosomal-recessive trait.

Probably at least six POAG genes are at fault. The POAG loci are named GLC1, and a letter is added to indicate each new locus (the first described is GLC1A). One, the juvenileonset POAG GLC1A gene is on chromosome 1q21–31 [in the region of the trabecular meshwork protein gene (TIGR), also known as myocilin]. Glaucoma usually manifests in late childhood and early adulthood, and is moderately severe. The other five (at least) genes are related to adult-onset POAG and are milder than the juvenile form. These are GLC1B (2qcen–2q13, GLC1C (3q21–q24), GLC1D (8q23), GLC1E (10p), and GLC1F (7q35–q36).

2.Mutations in the myocilin/TIGR gene are present in 1% to 4% of POAG patients, but not in patients with pseudoexfoliation. Linkage analysis for maximum recorded IOP locates near marker D10S537 on 10q22 whereas maximum cup-to-disc ratio is near markers D1S197 to D1S220 on 1p32.

Inclusion of the myocillin Q368X mutation as a covariate suggests an interaction between this mutation and the IOP and cup-to-disc ratio loci.

The Thr377Met mutation in myocillin may represent a susceptibility allele for glaucoma. Other myocillin mutations, including Phe369Leu, Ile-

360Asn, Ala363Thr, and Thr448Pro, have been associated with 2.9% of POAG in Japanese individuals. The nonsense mutation Gln368Stop is found in western populations but not in India or

Japan. The Gln368STOP mutation is not associated with earlier onset or di erent clinical course of POAG or ocular hypertension than those disorders in individuals lacking the mutation.

a.The GLC1A Thr377Met mutation in the myocilin gene has been associated with glaucoma that has a younger age of onset and higher peak IOP than in pedigrees with with the more common Gln368STOP mutation. Additionally, individuals with the Thr377Met mutation are more likely to undergo filtration surgery.

b.In French patients, myocilin gene mutations other than Q368X are associated with a younger age at diagnosis than that of Q368X carriers or of patients with a normal MYOC. In Australia, a founder e ect Q368STOP mutation in the myocilin gene has been detected in 15 families. The families, therefore, share a common ancestor who probably lived prior to the European settlement of Australia.

c.The pathobiology of myocilin gene mutations is probably the result of gain of function rather than from haploinsu ciency.

d.It is probable that accumulation of mutant myocilin in the rough endoplasmic reticulum in glaucoma stresses the endoplasmic reticulum and may produce cytotoxicity in the human trabecular meshwork cells. Most known myocilin mutations localize to the C-terminus, an olfacto- medin-like domain. This material is probably not properly processed in the endoplasmic reticulum. Therefore the material accumulates into insoluble aggregates.

e.In cultured trabecular cells, increased myocilin expression results in loss of actin stress fibers and focal adhesions. Cell adhesion to fibronectin and cell spreading are also compromised. The impact on cellular adhesion is similar to matricellular proteins. Increased sensitivity to apoptosis is also found in cells displaying enhanced myocilin expression.

1). Frequently, a family history of POAG is reported.

2). A high incidence of impaired facility of outflow is found in younger members of families with POAG.

A more appropriate name for POAG might be glaucomatous optic neuropathy because the primary defect is probably in the optic nerve.

F.Normal-tension (improperly called low-tension) glaucoma is a subdivision of POAG (see section Introduction in this chapter).

G.Histology and pathophysiology

1.Optic nerve (see pp. 658–660 in this chapter)

2.Little is known about the early histologic changes that take place in the region of the drainage angle because the number of human eyes that have wellcharacterized early open-angle glaucoma available for histologic examination is small (see Fig. 16.9).

3.Very little meaningful information can be derived from long-standing, “end-stage” diseased eyes or from tiny biopsies taken during surgery for control of glaucoma.

Many reported histologic changes such as “sclerosis” of the trabecular meshwork, compression or absence of Schlemm’s canal, or decrease in number of macrovacuoles in the endothelial lining of Schlemm’s canal are probably end-stage changes, artifacts, or misinterpretations. Proteomic analysis of the trabecular meshwork in POAG demonstrates cochlin, which is a protein associated with the deafness disorder DFNA9 in patients with POAG but not in the normal trabecular meshwok. Deposits of cochlin and mucopolysaccharide are present in human trabecular meshwork around Schlemm’s canal, similar to that observed in the cochlea in DFNA9 deafness. It is postulated that cochlin may disrupt trabecular meshwork architecture and render its components, like collagen, more susceptible to degradation and collapse. Thus, the cochlin would interact with the extracellular matrix (ECM), leading to a cascade of effects, resulting in decreased aqueous outflow.

4.Aging changes in the drainage angle of the anterior chamber

a.COAG is usually associated with a progressive decrease in the facility of outflow of aqueous humor from the anterior chamber.

b.The resulting IOP becomes incompatible with the continued health of the tissues of the optic nerve head.

c.Decreased facility of outflow results from an obstruction produced by excessive aging changes in the drainage angle.

d.The degree of obstruction is a quantitative problem; two extremes of excessive obstruction are:

1). Proliferation of the endothelium (and possibly of juxtacanalicular connective tissue cells) lining Schlemm’s canal into its lumen for much of its circumference

2). Compaction of the uveal meshwork against the scleral roll, producing a prominent scleral spur (“hyalinization”of adjacent ciliary muscle and atrophy of the iris root also occur)

e.The two major aging changes—each may be seen in almost pure form, or may be combined.

1). They may also be associated with proliferations of trabecular endothelial cells in the meshwork.

2). COAG depends on the amount of aqueous inflow and the degree of obstruction to outflow caused by the aging changes (see Fig.

16.10).

f.Molecular analysis of human trabecular meshwork in glaucoma demonstrates oxidative DNA damage in glaucoma.

The aging changes listed here as occurring in the tissues of the drainage angle are mostly irreversible. Their obstructive nature may be circumvented for short or long periods with a variety of pharmacologic agents. Thus, whether glaucoma develops is a quantitative problem based on whether aging changes of decreased outflow exceed aging changes of decreased inflow.

5.Ischemia involving the aqueous outflow pathway has been postulated to contribute to the development of POAG.

6.Oculomedin is expressed in stretched trabecular cells in tissue culture. It is localized to the trabecular meshwork, Schlemm’s canal endothelium, retinal photoreceptor cells, and corneal and conjunctival epithelium. Its gene is composed of two exons located within the intron of the Clorf27 gene on chromosome 1q25, near and telomeric to myocilin.

7.Carbonic anhydrase (CA12) enzyme mRNA is increased in neural pigment epithelial cells in glaucoma patients, which may be a target for therapy in glaucoma.

Secondary Closed-Angle Glaucoma

Causes

I.Chronic primary angle-closure glaucoma

A.Repeated attacks of primary closed-angle glaucoma may give rise either to peripheral anterior synechiae and secondary closed-angle glaucoma, or to trabecular damage and secondary COAG.

In black patients, the acute attacks may be subclinical while the closure of the angle progresses relentlessly.

B.Histologically, peripheral anterior synechiae are seen,

sometimes broad based.

II.Phacomorphic

A.Swelling of the lens may cause peripheral anterior synechiae (through pupillary block and iris bombé).

B.More frequently, a maturing cataractous lens swells rapidly and simulates primary closed-angle glaucoma.

III.Subluxated or anteriorly dislocated lens can cause a pupillary block that, if not relieved, leads to iris bombé, peripheral anterior synechiae, and secondary angle closure.

IV. Persistent flat chamber after surgical or nonsurgical trauma may lead to broad-based peripheral anterior synechiae, occasionally causing total anterior synechiae.

V.Iridocorneal endothelial (ICE) syndrome

A.The ICE syndrome consists of a spectrum of changes that include the iris nevus (Cogan–Reese) syndrome, Chandler’s syndrome, and essential iris atrophy.

Antibody titers to the Epstein–Barr virus are increased in patients who have the ICE syndrome; the significance of this increase remains to be clarified.

1.All three entities share a basic corneal endothelial defect and iris involvement.

a.Specular microscopy shows abnormal cells, called ICE cells, that are larger and more pleomorphic than normal endothelial cells, and whose specular reflex shows light–dark reversal

(i.e., the cell surface is dark instead of light, often with a central light spot, and the intercellular junctions are light instead of dark).

Electron microscopically, ICE cells show epithelial features (e.g., tonofilaments, desmosomes, multilayering, microvilli, and conspicuous “blebs”).

b.The abnormal endothelial cells may coexist with normal endothelial cells, a condition called subtotal ICE, when 25% to 75% of the total cells are ICE cells.

Immunohistochemical stains of the corneal endothelium are positive for AE1 and AE3 (epidermal keratins) and vimentin, which, along with electron microscopic observations, suggests an “epithelialization” of the endothelium, and may explain, at least in part, the aggressive proliferative nature of the corneal endothelium in the ICE syndrome.

c.On specular microscopy, the clinically uninvolved contralateral eye often demonstrates subclinical corneal abnormalities such as a relatively low percentage of hexagonal cells and a relatively high coe cient of variation of cell area.

2.All ICE syndrome entities tend to be unilateral, occur in young women, and cause corneal edema when the IOP is only slightly elevated or even normal.

3.Glaucoma occurs in approximately 50% of cases.

4.Although in their pure forms the three entities are distinct clinicopathologic types, findings overlap so much in many cases that they are considered variants of the same process.

5.Each variant is described separately, but all are considered to belong to the ICE syndrome.

Common

Fine guttatalike lesions common

100%

Marked (essential iris atrophy), moderate (iris nevus syndrome), or mild (Chandler’s syndrome)

Occasional to common

80%

None

Unilateral

Women > men

Third and fourth decades

Fairly rapid formation of synechiae and severe glaucoma

Thickened, multilayered Descemet’s membrane; endothelial cells attenuated, reduced in number, and missing in areas

Corneal endothelilum and Descemet’s membrane over trabecular meshwork and iris

Posterior polymorphous dystrophy (PPMD; see p. 307 in Chapter 8) shares some characteristics with the ICE syndrome (Table 16.1) such as endothelial degeneration, corneal edema, iridocorneal adhesions, endothelialization of the anterior-chamber angle, and glaucoma. Differences between the entities include the structure of the corneal endothelium (epithelial-like in PPMD), hereditary transmission (positive in PPMD), laterality (bilateral in PPMD), and progression (relatively stable in PPMD).

B.Iris nevus syndrome (Figs 16.11 and 16.12).

1.The iris nevus syndrome mainly occurs in young women, and is characterized by several of the following signs: peripheral anterior synechiae, often associated with atrophic defects in adjacent iris stroma; matted appearance of iris stroma; a velvety, whorl-like iris surface; loss of iris crypts; fine iris nodules; pupillary eversion (ectropion uveae); heterochromia; secondary glaucoma;and corneal edema at only slightly elevated, or even normal, IOP.

2.Histologically, the two main features are: (1) a di use or nodular, or both, nevus of the anterior surface of the iris; and (2) corneal endothelializa-

tion of the anterior-chamber angle and anterior surface of the iris.

C.Chandler’s syndrome (Fig. 16.13)

1.The condition, probably the most common variant of the ICE syndrome, is unilateral and occurs mainly in young women.

2.Endothelial dystrophy causes corneal edema to develop at a slightly elevated or normal IOP.

Patients with Chandler’s syndrome tend to have worse corneal edema and less glaucoma than patients with the other two variants.

3.Small peripheral anterior synechiae and mild pupillary distortion are found.

4.Small areas of iris stromal thinning may be found, but through-and-through holes are rare.

5.The glaucoma is usually mild.

6.Histology

a.The iris stroma is atrophic.

b.In the areas of iris hole formation, the stroma and pigment epithelium are absent.