LENS DISORDERS
Lens is a biconvex transparent structure behind the iris and in front of vitreous body, which transmits and permits eye to focus the visual image over the retina.
Cataract, i.e.
focal or diffuse opacity of lens in children may be congenital or acquired (Table 26.10). However, congenital cataract may not be apparent at birth and develop after for few weeks or months. Congenital cataracts are one of the most important and consistent indicators of intrauterine infections, especially congenital rubella syndrome. Early detection and surgery is essential in children due to rapid development of deprivation amblyopia.TABLE 26.10: Causes of cataract in children
Congenital
• Developmental: Preterms, vascular remnants1
• Familial
• Intrauterine (TORCH) infections
• Chromosomal: Trisomies, turner syndrome
• Genetic: Galactosemia, lowe syndrome
Acquired
• Post-traumatic: Contusion, penetrating injuries
• Post-infective: Iridocyclitis
• Metabolic: Diabetes, hypoglycemia, hypocalcemia
• Endocrinal: Hypoparathyroidism
• Iatrogenic: Steroids2, radiation, Iiypervitaminosis D 1Mittendorf's dots - persistent hyaloid remnants
2usually posterior subcapsular
Ectopia lentis, i.e. displacement or subluxation of lens from its normal position may be congenital: (a) isolated familial defect, (b) marfan syndrome (superiolateral), (c) homocystinuria (inferio-medial), (d) Ehler-Danlos syndrome; or acquired after, (e) ocular trauma, (f) ocular diseases, e.g. uveitis or tumors. Most of these cases are asymptomatic, though some may develop blurred vision and refractive errors. Iridodonesis, i.e. tremulousness of iris, is an important sign of ectopia lentis along with deep anterior chamber and visible crescentic edge of lens.
26.2.11