Congenital Cataract

Congenital cataract is lens opacity present at birth or developing in infancy, and a leading treatable cause of childhood blindness (prevalence about 1 to 6 per 10,000 live births in high income settings and higher elsewhere).

• Bilateral cases (about two thirds): often inherited (autosomal dominant in most families; crystallin, connexin and other lens gene mutations) or metabolic or syndromic.
• Unilateral cases: usually sporadic, associated with persistent fetal vasculature, posterior lenticonus, trauma.
• Causes: intrauterine infection (rubella, cytomegalovirus, toxoplasmosis, herpes, syphilis, varicella), metabolic (galactosaemia, hypoglycaemia, hypocalcaemia, Fabry disease, mannosidosis, Wilson disease), chromosomal (trisomy 21, 13, 18, Turner), Lowe syndrome (oculocerebrorenal), Alport, Marfan, myotonic dystrophy, neurofibromatosis type 2, prematurity, drugs (corticosteroids), radiation.
• The visual outcome depends on timing of surgery because of deprivation amblyopia in the critical period (first weeks to months of life).

• White pupil (leukocoria) or absent red reflex noticed at birth or in early life, strabismus, nystagmus (suggests bilateral dense cataract with poor vision before 2 to 3 months), poor visual fixation and following.
• Morphology: nuclear, lamellar (zonular), sutural, anterior polar, posterior polar, total, posterior lenticonus, coralliform, blue dot cerulean.
• Associated: microphthalmia, microcornea, aniridia, persistent fetal vasculature, glaucoma.
• Systemic features guided by cause: dysmorphism, hepatosplenomegaly (galactosaemia), hearing loss, renal disease.

• Red reflex testing at birth and at 6 to 8 weeks; any abnormal or asymmetric reflex requires urgent ophthalmology review.
• Full assessment: visual behaviour, fixation preference, nystagmus, slit lamp or handheld examination, pupillary response, intraocular pressure (under anaesthesia), axial length and keratometry, B-scan if no view.
• Aetiological workup: TORCH and varicella serology and PCR, urine reducing substances and red cell galactose-1-phosphate uridyltransferase, blood glucose, calcium, phosphorus, serum ferritin in some, urine amino acids (Lowe), karyotype, genetic panel; paediatric review; family examination (parents' lenses).
• Dense central cataract more than 3 mm in diameter in the visual axis is visually significant.

• Visually significant unilateral dense cataract: surgery by about 6 weeks of age (best outcomes before 6 weeks and no later than 4 months), with aggressive amblyopia therapy.
• Bilateral dense cataracts: surgery by 6 to 8 weeks, with the second eye within 1 to 2 weeks to limit amblyopia (some surgeons operate on both eyes in one session).
• Partial or non-axial cataract: observe with dilation (tropicamide 0.5 percent or cyclopentolate 0.5 percent) and monitor.
• Surgical technique: lensectomy with posterior capsulotomy and anterior vitrectomy through a limbal or pars plana approach for infants under 6 to 7 years, to prevent opacification of the visual axis; primary intraocular lens implantation is debated in infants under 6 to 7 months and is more commonly done at 2 years or later; aphakia is corrected with contact lenses (initial power about +25 to +30 dioptres, tapering as the eye grows) or spectacles.
• Postoperative: prednisolone acetate 1 percent four to six times daily tapered over 4 to 6 weeks, cycloplegic (atropine 0.5 to 1 percent daily), antibiotic drops for 1 to 2 weeks.
• Amblyopia therapy: patching the better eye 3 to 6 hours daily for unilateral cases, optical correction, close follow up.
• Complications: glaucoma (10 to 30 percent, can develop years later, so lifelong intraocular pressure monitoring), visual axis opacification, uveitis, retinal detachment, strabismus, nystagmus.
• Metabolic cause: dietary galactose restriction in galactosaemia (lactose free formula, soy), correction of hypocalcaemia and hypoglycaemia.
• Genetic counselling and screening of family members.