Congenital Cataracts

What congenital cataracts are

The lens sits behind the pupil and focuses light onto the retina. In a cataract, proteins in the lens clump together and make it cloudy. Congenital cataracts vary from tiny dots that do not affect vision to dense opacities that block the whole lens. They can affect one eye (unilateral) or both (bilateral).

Why early treatment matters

A baby's brain learns to see during the first few months of life. If one or both eyes receive a blurred image, the visual pathways do not develop properly, causing amblyopia (lazy eye). After the critical period, removing the cataract cannot fully restore vision. For dense cataracts, surgery is usually recommended by about 4 to 6 weeks of age for one eye and by about 8 to 10 weeks for both eyes.

Signs and symptoms

• Leukocoria: a white, gray or cloudy pupil
• Abnormal red reflex: in flash photographs one pupil looks white or dull instead of red
• Not making eye contact or following faces and objects
• Nystagmus: rapid, involuntary wobbling eye movements, often a sign of poor vision in both eyes
• Strabismus: a turned eye
• Light sensitivity

Many cataracts are detected at the newborn and 6- to 8-week checks, when a clinician shines a light into each eye to check the red reflex.

Causes

• Idiopathic: no cause is found in many unilateral cases and a large share of bilateral cases.
• Inherited: often autosomal dominant; a parent may have had childhood cataracts.
• Infections during pregnancy: rubella, toxoplasmosis, cytomegalovirus, herpes simplex and varicella (the TORCH infections).
• Metabolic disorders: galactosemia, low blood sugar or low calcium in the newborn.
• Chromosomal and genetic syndromes: Down syndrome, Lowe syndrome and others.
• Prematurity and some medicines in pregnancy.
• Other eye abnormalities: such as persistent fetal vasculature, usually in one eye.

Bilateral cataracts are more often linked to inherited or systemic causes. Unilateral cataracts are more often isolated and local to the eye.

Diagnosis

1. Red reflex test at newborn and infant checks.
2. Full examination by a pediatric ophthalmologist: dilating drops, slit lamp examination of the lens, examination of the retina, eye pressure and measurement of the eye.
3. Ultrasound of the eye if the cataract blocks the view of the retina.
4. Investigations for bilateral cataracts: blood and urine tests for infection and metabolic disease, and genetic testing, often coordinated with a pediatrician.

Treatment

Observation

Small or partial cataracts that do not significantly block vision are monitored closely, sometimes with dilating drops or patching to support visual development.

Surgery

For visually significant cataracts, the cloudy lens is removed under general anesthesia (lensectomy), often with removal of the back of the lens capsule and some of the vitreous gel to stop clouding from returning.

Focusing after surgery

Without its lens, the eye cannot focus (aphakia). Options:

• Contact lenses: common for infants; changed as the eye grows.
• Glasses: especially for bilateral aphakia.
• Intraocular lens (IOL): an artificial lens implanted during surgery; more often used in children over about 1 to 2 years. Findings from the Infant Aphakia Treatment Study showed similar visual results with contact lenses in young infants and more complications with early IOL implantation.

Amblyopia treatment

Patching the better eye for part of each day forces the brain to use the treated eye. Consistent patching for months to years is essential, especially in one-sided cataracts.

Complications

• amblyopia, despite treatment
• glaucoma after surgery, which can develop years later and needs lifelong eye pressure checks
• clouding behind an implanted lens (visual axis opacification), sometimes needing further surgery
• strabismus and nystagmus
• retinal detachment (rare, later in life)
• infection or inflammation after surgery

Outlook

Children with small, non-dense cataracts often have near-normal vision. With early surgery and good follow-up, many children with bilateral dense cataracts achieve useful vision, often enough to attend mainstream school and, later, to drive. Results in one-sided cataracts depend greatly on how well patching and contact lens wear are kept up. Regular eye checks are needed throughout life.

Frequently asked questions

What causes congenital cataracts?

Many have no identifiable cause. Known causes include inherited gene changes, infections during pregnancy such as rubella, metabolic disorders such as galactosemia, chromosomal conditions such as Down syndrome, and other eye developmental abnormalities.

How are congenital cataracts detected?

They are usually found during the newborn red reflex test, when a light is shone into each eye. Parents may notice a white pupil, a missing red eye in flash photos, wobbling eyes or a baby who does not follow faces. An ophthalmologist confirms the diagnosis.

When should congenital cataracts be removed?

Dense cataracts that block vision are typically removed within the first 4 to 6 weeks for one eye, and by about 8 to 10 weeks for both eyes. Early surgery gives the brain the best chance to develop normal vision.

Can a baby see normally after cataract surgery?

Many children achieve good vision, especially with early surgery, consistent use of contact lenses or glasses, and patching. Vision may not be perfect, and outcomes are usually better for bilateral cataracts than for a single affected eye.

Are congenital cataracts hereditary?

Some are. About a quarter or more of bilateral cases are inherited, often from a parent who also had childhood cataracts. Parents with a history of childhood cataracts should have their newborn's eyes examined early.