Ectopia Lentis Clinical Presentation

Common presenting symptoms (visual disturbance) include the following:

• Red painful eye (secondary to trauma)

• Decreased distance visual acuity (secondary to astigmatism or myopia)

• Poor near vision (loss of accommodative power)

• Monocular diplopia

Determine if there is a history of ocular trauma.

Obtain a detailed history investigating possible systemic disease associations, as follows:

• Cardiovascular disease (eg, Marfan syndrome)

• Skeletal problems -Marfan syndrome, Weil-Marchesani syndrome, or homocystinuria

• Pertinent family history - Consanguinity, mental retardation, or unexplained deaths at young age (eg, autosomal recessive conditions, including homocystinuria, hyperlysinemia, ectopia lentis et pupillae, ^[7] or sulfite oxidase deficiency)

A pediatrician or an internal medicine physician should perform a comprehensive physical examination of patients with ectopia lentis of undetermined etiology because of the commonly associated hereditary systemic disorders.

The ocular examination should include the elements listed below.

Vision

Ectopia lentis is potentially visually debilitating.

Visual acuity varies with the degree of malpositioning of the lens.

Amblyopia is a common cause of decreased vision in congenital ectopia lentis and is preventable and treatable.

External ocular examination

Attention to orbital anatomy is important to evaluate for hereditary malformations (eg, enophthalmos with facial myopathic appearance seen in patients with Marfan syndrome). ^[8]

Measure corneal diameter (megalocornea is associated with Marfan syndrome).

Strabismus is not uncommon (secondary to amblyopia).

Retinoscopy and refraction

Careful retinoscopy and refraction is essential, often revealing myopia with astigmatism.

Keratometry may help ascertain degree of corneal astigmatism.

Slit lamp examination

Evaluate lens position, and identify phacodonesis or cataract.

Measure intraocular pressure. Elevation may indicate secondary glaucoma. Causes of glaucoma in ectopia lentis include the following: (1) pupillary block, (2) phacoanaphylaxis or phacolytic, (3) posttraumatic angle recession, (4) poorly developed angle structures, and (5) lens in the anterior chamber.

Dilated fundus examination

Retinal detachment is one of the most serious consequences of a dislocated lens.

The numerous causes of ectopia lentis are discussed below.

Traumatic dislocation

Traumatic dislocation is the most common cause.

Hereditary ectopia lentis without systemic manifestations

Single (isolated) ectopia lentis is characterized by autosomal dominant inheritance with the genetic defect located on chromosome 15, causing a dysfunctional zonular apparatus. Microspherophakia is common. Although most often present at birth, late onset has been described. Typically, the lens is displaced supertemporally.

Ectopia lentis et pupillae is characterized by asymmetric eccentric pupils that are displaced in the opposite direction of the lens dislocation (toward the most dysfunctional zonular fibers). The condition usually is bilateral and typically autosomal recessive. The irides often appear atrophic with transillumination defects on slit lamp examination. ^[7] Cataracts commonly are seen. ^[9]

Systemic conditions commonly associated with ectopia lentis

Marfan syndrome is the most frequent cause of heritable ectopia lentis. The syndrome is transmitted as an autosomal dominant trait with variable expressivity and has a prevalence of approximately 5 per 100,000. Several point mutations involving the fibrillin gene on chromosomes 15 and 21 have been described and may relate to incompetent zonular fibers. Salient features of Marfan syndrome include tall stature, arachnodactyly, joint laxity, mitral valve prolapse, aortic dilatation, axial myopia, and increased incidence of retinal detachment. Lens dislocation occurs in about 75% of patients with Marfan syndrome and usually is bilateral, symmetrical, and supertemporal. ^[10]

Homocystinuria is the second most common cause of hereditary ectopia lentis. It is an inborn error of metabolism most often caused by a near absence of cystathionine b-synthetase (the enzyme that converts homocysteine to cystathionine). Patients typically have fair skin with coarse hair, osteoporosis, mental retardation (nearly 50%), seizure disorder, marfanoid habitus, and poor circulation. Thromboembolic events constitute the major threat to survival, especially following general anesthesia. Lens luxation usually is bilateral, symmetrical, and inferonasal, and presents in nearly 90% of patients. Deficient zonular integrity secondary to the enzymatic defect has been implicated as the primary cause of lens displacement.

Weil-Marchesani is a rare syndrome characterized by skeletal malformations (eg, short stature, brachycephaly, limited joint mobility, well-developed muscular appearance) and ocular abnormalities (eg, ectopia lentis, microspherophakia, lenticular myopia). The inheritance pattern is not well understood. Microspherophakia is the most prominent feature of this syndrome. High incidence of lens subluxation occurs inferiorly, often progressing to complete dislocation. Pupillary block glaucoma is common; therefore, prophylactic laser peripheral iridotomies are recommended. ^[11]

Sulfite oxidase deficiency is an extremely rare disorder caused by a defect in sulfur metabolism. Salient features include progressive CNS abnormalities that develop within the first year of life in concert with ectopia lentis.

Hyperlysinemia is an extremely rare autosomal recessive enzymatic defect of amino acid metabolism that is characterized by mental retardation and lens dislocation. Diagnosis is made by demonstration of increased plasma levels of lysine.

Primary ocular disorders associated with ectopia lentis

These include the following:

• Congenital glaucoma/buphthalmos

• Pseudoexfoliation syndrome

• Syphilis/chronic uveitis

• Retinitis pigmentosa

• Megalocornea

• Aniridia

• Hypermature cataract

• Intraocular tumor

• High myopia

Systemic diseases rarely associated with ectopia lentis

These include the following:Ehlers-Danlos syndrome

• Crouzon disease

• Refsum syndrome

• Kniest syndrome

• Mandibulofacial dysostosis

• Sturge-Weber syndrome

• Conradi syndrome

• Pfaundler syndrome

• Pierre Robin syndrome

• Wildervanck syndrome

• Sprengel deformity

The most common ocular complications of ectopia lentis include amblyopia, uveitis, glaucoma, and retinal detachment; appropriate treatment for these specific entities should be implemented.