Lens

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8

Lens

Congenital Anomalies

Definition

Variety of developmental lens abnormalities:

Coloboma

Focal inferior lens flattening due to ciliary body coloboma with absence of zonular support (not a true coloboma); other ocular colobomata (iris) usually exist. Ciliary body tumors may cause a secondary lens “coloboma.”

Lenticonus

Cone-shaped lens due to bulging from a thin lens capsule; either anteriorly or posteriorly, rarely in both directions.

Anterior

Usually males; bilateral; may be associated with Alport’s syndrome (see Congenital Cataract section below).

Posterior

More common; slight female predilection; may have associated cortical lens opacities, may be associated with Lowe’s syndrome (see Congenital Cataract section below).

Lentiglobus

Globe-shaped lens caused by bulging from thin lens capsule; rare.

Microspherophakia

Small spherical lens; may be an isolated anomaly or part of a syndrome (i.e., dominant spherophakia, Weill–Marchesani syndrome, Lowe’s syndrome, Alport’s syndrome, Peter’s anomaly, rubella).

Mittendorf Dot

A small white spot on the posterior lens capsule that represents a remnant of the posterior tunica vasculosa lentis where the former hyaloid artery attached.

Symptoms

Asymptomatic (Mittendorf dot, coloboma); may have decreased vision (lenticonus, lentiglobus, and microspherophakia), diplopia, or symptoms of angle-closure glaucoma (microspherophakia).

Signs

Normal or decreased visual acuity; may have amblyopia, strabismus, nystagmus, myopia, and an “oil-droplet” fundus reflex on retroillumination in lenticonus and lentiglobus; may have dislocated lens and increased intraocular pressure in microspherophakia.

Differential Diagnosis

See above.

Evaluation

 Complete ophthalmic history and eye exam with attention to cycloplegic refraction, retinoscopy, gonioscopy, lens, and ophthalmoscopy.

Management

 Correct any refractive error.

 Patching or occlusion therapy for amblyopia (see Chapter 12).

 Microspherophakia causing pupillary block is treated with a cycloplegic (scopolamine 0.25% tid or atropine 1% bid); may also require laser iridotomy or lens extraction (see Secondary Angle-Closure Glaucoma section in Chapter 6).

Prognosis

Usually good; poorer if amblyopia exists.

Congenital Cataract

Definition

Congenital opacity of the crystalline lens usually categorized by location or etiology:

Capsular

Opacity of the lens capsule, usually anteriorly.

Lamellar or Zonular

Central, circumscribed opacity surrounding the nucleus; “sand dollar” appearance.

Lenticular or Nuclear

Opacity of the lens nucleus.

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Figure 8-6 Congenital nuclear cataract with central white discoid appearance.

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Figure 8-7 Same patient as Figure 8-6 demonstrating congenital nuclear cataract as viewed with retroillumination.

Polar

Central opacity located near the lens capsule, anteriorly or posteriorly.

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Figure 8-8 Congenital posterior polar cataract.

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Figure 8-9 Same patient as Figure 8-8 demonstrating congenital polar cataract in retroillumination.

Sutural

Opacity of the Y-shaped sutures in the center of the lens.

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Figure 8-10 Congenital cataract with prominent suture lines.

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Figure 8-11 Same patient as Figure 8-10 demonstrating congenital sutural cataract in retroillumination.

Etiology
Hereditary or Syndromes

Without chromosomal abnormalities

Autosomal dominant (AD), autosomal recessive (AR), X-linked.

With chromosomal abnormalities

Down’s syndrome (snowflake cataracts), Turner’s syndrome, and others.

Other syndromes

Craniofacial, central nervous system, skin.

Intrauterine Infections

Congenital rubella syndrome

Cataracts, glaucoma, microcornea, microphthalmos, iris hypoplasia, and retinopathy with characteristic fine, granular, salt-and-pepper appearance (most common finding). Other complications include prematurity, mental retardation, neurosensory deafness, congenital heart disease, growth retardation, hepatosplenomegaly, interstitial pneumonitis, and encephalitis.

Congenital varicella syndrome

Cataracts, chorioretinitis, optic nerve atrophy or hypoplasia, nystagmus, and Horner’s syndrome. Systemic findings include hemiparesis, bulbar palsies, dermatomal cicatricial skin lesions, developmental delay, and learning difficulties.

Metabolic

Galactosemia

Bilateral, oil-droplet cataracts from accumulation of galactose metabolites (galactitol) due to hereditary enzymatic deficiency; usually galactose 1-phosphate uridyltransferase, also galactokinase. Associated with mental retardation, hepatosplenomegaly, cirrhosis, malnutrition, and failure to thrive. Mapped to chromosomes 1p (GALE gene), 9p (GALT gene) and 17q (GALK1 gene).

Lowe’s oculocerebrorenal syndrome (X-linked)

Small discoid lens, posterior lenticonus, and glaucoma. Systemic findings include acidosis, aminoaciduria, renal rickets, hypotonia, mental retardation. Female carriers have posterior, white, punctate cortical opacities and subcapsular, plaque-like opacities. Mapped to chromosome Xq25 (OCRL gene).

Alport’s syndrome (AD)

Basement membrane disease associated with acute hemorrhagic nephropathy, deafness, anterior lenticonus, anterior polar or cortical cataracts, and albipunctatus-like spots in the fundus. Mapped to chromosome Xq22 (COL4A5 gene [80% of cases], also COL4A3 and COL4A4 genes).

Other metabolic diseases

Hypoglycemia, hypocalcemia (diffuse lamellar punctate opacities), Fabry’s disease (spoke-like cataracts in 25%), mannosidosis (posterior spoke-like opacities).

Ocular Disorders

Persistent hyperplastic primary vitreous, Peter’s anomaly, Leber’s congenital amaurosis, retinopathy of prematurity, aniridia, posterior lenticonus, tumors.

Other

Birth trauma, idiopathic, and maternal drug ingestion.

Epidemiology

Congenital cataracts occur in approximately 1 of 2000 live births. Roughly one-third are isolated, one-third are familial (usually dominant), and one-third are associated with a syndrome; most unilateral cases are not metabolic or genetic.

Symptoms

Variable decreased vision; may notice white pupil or eye turn.

Signs

Decreased visual acuity, leukocoria, amblyopia; may have strabismus (usually with unilateral cataract), nystagmus (usually does not appear until 2–3 months of age; rarely when cataracts develop after age 6 months), amblyopia; may have other ocular or systemic findings if syndrome exists.

Differential Diagnosis

See Leukocoria in Chapter 7.

Evaluation

 Complete ophthalmic history with attention to family history of eye disease, trauma, maternal illnesses and drug ingestion during pregnancy, systemic diseases in the child, and birth problems.

 Complete eye exam with attention to cycloplegic refraction, retinoscopy, tonometry, gonioscopy, lens (size and density of the opacity as viewed with retroillumination), and ophthalmoscopy.

 May require examination under anesthesia.

 Keratometry and biometry when intraocular lens (IOL) implantation is anticipated.

 Lab tests: TORCH titers (toxoplasmosis, other infections [syphilis], rubella, cytomegalovirus, and herpes simplex), fasting blood sugar (hypoglycemia), urine-reducing substances after milk feeding (galactosemia), calcium (hypocalcemia), and urine amino acids (Lowe’s syndrome).

 B-scan ultrasonography if unable to visualize the fundus (can perform through the lids of a crying child).

 Pediatric consultation.

Management

 Dilation (tropicamide 1% [Mydriacyl] with or without phenylephrine 2.5% [Mydfrin tid) may be used as a temporary measure before surgery to allow light to pass around the cataract; however, surgery should not be delayed.

 If the cataract obscures the visual axis (media opacity > 3 mm) or is causing secondary ocular disease (glaucoma or uveitis), cataract extraction should be performed within days to a week after diagnosis in infants because delay may lead to amblyopia; postoperatively, the child requires proper aphakic correction with contact lens or spectacles if bilateral; depending on age and etiology, consider IOL implantation.

 If the cataract is not causing amblyopia, glaucoma, or uveitis, the child is observed closely for progression.

 Patching or occlusion therapy for amblyopia (see Chapter 12).

 Almost all patients with visually significant, unilateral, congenital cataracts have strabismus and may require muscle surgery after cataract extraction.

 Restrict dietary galactose in galactosemia.

Prognosis

Depends on age and duration of visually significant cataract prior to surgery; poor if amblyopia exists.

Acquired Cataract

Definition

Lenticular opacity usually categorized by location or etiology:

Cortical Degeneration

Caused by swelling and liquefaction of the cortical fiber cells. Various types:

Spokes and vacuoles

Asymmetrically located, radial, linear opacities and punctate dots.

Mature cataract

Completely opacified cortex causing the lens to appear white; no red reflex visible from fundus.

Morgagnian cataract

Mature cataract with dense nucleus displaced inferiorly in completely liquefied, white cortex.

Hypermature cataract

After morgagnian cataract formation, the lens shrinks, the capsule wrinkles, and calcium deposits can form; proteins may leak into the anterior chamber causing phacolytic glaucoma.

Nuclear Sclerosis

Centrally located lens discoloration / opalescence (yellow-green or brown [brunescent]); caused by deterioration of the central lens fiber cells.

Subcapsular Cataract

Anterior subcapsular

Central fibrous plaque caused by metaplasia of the central zone lens epithelial cells beneath the anterior lens capsule. Medications can cause anterior subcapsular stellate changes; acute angle-closure attacks can cause anterior subcapsular opacities (glaukomflecken) due to lens epithelial necrosis.

Posterior subcapsular
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