Paediatric Cataract
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Direct answer
Six weeks is a deadline, not an opinion, for a unilateral congenital cataract: deprivation amblyopia begins within the first two months of life, so a dense unilateral opacity is operated at around six weeks of age, a bilateral one by eight to ten weeks — every week of delay after that trades permanent vision. Causes split into developmental or genetic (often autosomal dominant), intrauterine infection (rubella the classic, with salt-and-pepper retinopathy, deafness and cardiac disease; also toxoplasmosis, cytomegalovirus, herpes), metabolic disease (galactosaemia with its oil-droplet lens, Lowe oculocerebrorenal syndrome, diabetes), posterior lenticonus or lentiglobus — a common cause of unilateral developmental cataract — persistent fetal vasculature, trauma and steroids. Surgery differs from the adult operation: lensectomy with primary posterior capsulectomy and anterior vitrectomy (because posterior capsule opacification is otherwise near-universal), with intraocular lens implantation commonly deferred to about one to two years of age in many units, and amblyopia therapy determining the final visual outcome more than the surgery itself.
What you must remember
- Timing rules: unilateral dense congenital cataract — surgery around six weeks of age; bilateral — eight to ten weeks; a cataract presenting with nystagmus has already deprived the visual system and stamped in deep amblyopia, and the prognosis is correspondingly poor.
- Presentation to recognise: leukocoria, squint, nystagmus (late), failure to fix and follow, or an abnormal red reflex at the newborn check — formalised in child screening programmes.
- Leukocoria differential (the exam's list): retinoblastoma (calcification on ultrasound), cataract, persistent fetal vasculature (microphthalmia, retrolental fibrovascular mass), Coats disease (exudates, older boys), toxocariasis, retinopathy of prematurity, retinal detachment.
- Rubella syndrome quartet: cataract plus salt-and-pepper retinopathy, sensorineural deafness and congenital heart disease — and maternal vaccination is the prevention worth quoting.
- Metabolic pairings: galactosaemia (oil-droplet cataract, galactosuria, failure to thrive) and Lowe syndrome (cataract, hypotonia, intellectual disability, renal tubular dysfunction); lamellar cataract is the commonest developmental morphology.
- Surgical doctrine: lensectomy with posterior capsulectomy and anterior vitrectomy in young children, since capsule opacification in a growing eye is near-certain; intraocular lens implantation timing individualised, commonly after the first year, with meticulous biometry and undercorrection planned for the myopic shift of growth.
- Aphakic rehabilitation: bilateral aphakia — spectacles are acceptable and practical; unilateral aphakia — contact lens (or intraocular lens when implanted), because aniseikonia makes spectacle correction of one eye unworkable.
- Amblyopia therapy is the operation's second half: occlusion of the fellow eye by the tolerated schedule, refractive correction maintained relentlessly, and lifelong follow-up for the two late threats — glaucoma (a permanent risk after paediatric lensectomy, pressure checked at every visit) and visual axis opacification.
A white pupil at the six-week check
A mother reports her six-week-old son's left pupil has looked grey since birth. Dilate both eyes and think diagnosis before surgery. The left eye is microphthalmic with a retrolental fibrovascular stalk visible behind the lens and dragging of the ciliary processes: persistent fetal vasculature with a secondary cataract, and surgery is more hazardous. The exam's preferred scenario: a normal-sized eye with a dense white lens, ultrasound free of calcification — a unilateral developmental cataract, booked for lensectomy with posterior capsulectomy and anterior vitrectomy now, at seven weeks. No implant at this age in most Indian units — the eye will grow and myopise — so a contact lens is fitted within the first postoperative week and the fellow eye patched on a reducing schedule: the lens and the patching are the treatment, theatre was only the beginning. At two years a secondary implant is placed; the final acuity is written by the amblyopia programme, and every missed patch hour shows at the next visit.
Where candidates slip
First, timing: candidates answer "operate when older and safer", which is exactly wrong — the amblyopia clock outranks surgical convenience, and the marks attach to the six-to-eight-week numbers. Second, the leukocoria stem is answered "cataract" reflexively when the photograph shows a retrolental mass in a small eye; the examiners plant retinoblastoma, persistent fetal vasculature and Coats in these vignettes — calcification, microphthalmia and exudates carry the mark. Third, the implant question: intraocular lens in early infancy sounds modern but the standard teaching remains deferral with aphakic correction — the myopic shift argument is what the examiner wants heard. Fourth, glaucoma after paediatric cataract surgery is a lifelong risk — the "what must be monitored" answer is intraocular pressure alongside refraction.
Frequently asked questions
When should congenital cataract be operated?
Unilateral dense cataract at around six weeks of age and bilateral by eight to ten weeks, because deprivation amblyopia becomes irreversible within the first months of life.
Which congenital infection causes cataract with retinopathy, deafness and heart disease?
Congenital rubella — the classic triad with salt-and-pepper retinopathy, preventable by maternal vaccination.
Why does paediatric cataract surgery include posterior capsulectomy and anterior vitrectomy?
Because posterior capsule opacification develops in nearly all young children after surgery; removing the capsule and anterior vitreous keeps the visual axis clear.
How is unilateral aphakia corrected in an infant?
With a contact lens (or later secondary implant) plus amblyopia occlusion therapy — spectacles for a single aphakic eye produce intolerable anisometropia and image-size difference.
What late complication must be screened for life after paediatric cataract surgery?
Glaucoma — pressure monitoring at every follow-up — along with visual axis opacification and amblyopia recurrence.