Chapter 620 Abnormalities of the Lens
Cataracts
A cataract is any opacity of the lens (Fig. 620-1). Some are clinically unimportant; others significantly affect visual function. The incidence of infantile cataracts is approximately 2-13/10,000 live births. An epidemiologic study of infantile cataracts published in 2003 suggests that approximately 60% of cataracts are an isolated defect; 22% are part of a syndrome; and the remainder is associated with other unrelated major birth defects. Cataracts are more common in low birthweight infants. Infants at or below 2,500 g have a 3- to 4-fold increased odds of developing infantile cataracts. Some cataracts are associated with other ocular or systemic disease.
Differential Diagnosis
The differential diagnosis of cataracts in infants and children includes a wide range of developmental disorders, infectious and inflammatory processes, metabolic diseases, and toxic and traumatic insults (Table 620-1). Cataracts may also develop secondary to intraocular processes, such as retinopathy of prematurity, persistent hyperplastic primary vitreous, retinal detachment, retinitis pigmentosa, and uveitis. A portion of cataracts in children are inherited (Fig. 620-2).
Table 620-1 DIFFERENTIAL DIAGNOSIS OF CATARACTS
DEVELOPMENTAL VARIANTS
Prematurity (Y-suture vacuoles) with or without retinopathy of prematurity
GENETIC DISORDERS
Simple Mendelian Inheritance
Major Chromosomal Defects
Multisystem Genetic Disorders
Inborn Errors of Metabolism
ENDOCRINOPATHIES
CONGENITAL INFECTIONS
OCULAR ANOMALIES
MISCELLANEOUS DISORDERS
IDIOPATHIC
