Pediatric ophthalmology and inherited ocular disease
Paediatric ophthalmology is tested through the screening pathway: the red reflex, the fixation pattern, and the recognition that an infant eye is not a small adult eye. Inherited disease questions expect an inheritance pattern, a gene or pathway, and a plan for family screening.
The infant eye
Red reflex testing at birth and at every baby check detects cataract, retinoblastoma and anisometropia. Congenital glaucoma presents with tearing, photophobia, blepharospasm, corneal enlargement (buphthalmos) and Haab striae; because the globe is distensible, pressure may be only moderately raised. Congenital cataract is operated early to prevent dense amblyopia, with aphakic correction and occlusion therapy.
Retinopathy of prematurity
Screen babies below the birth weight and gestational age thresholds of the local programme, with indirect ophthalmoscopy and scleral indentation. Stage 1 is a demarcation line, stage 2 a ridge, stage 3 extraretinal fibrovascular proliferation, stage 4 partial and stage 5 total detachment. Plus disease with stage 3 in zone I or II is treated with laser or anti-VEGF. Late complications include myopia, strabismus and detachment.
Strabismus and amblyopia
Congenital esotropia appears before 6 months, is constant and large-angle; accommodative esotropia appears at 2 to 3 years with hyperopia. Amblyopia is cortical visual loss from abnormal experience; treat the cause first, then occlude.
Inherited disease
Retinitis pigmentosa is usually autosomal recessive, with night blindness, a ring scotoma and bone spicule pigment. Stargardt disease is recessive ABCA4-related with macular flecks; Best disease is dominant with a vitelliform lesion; Leber congenital amaurosis presents in infancy with nystagmus and poor vision, and RPE65-related disease is treatable with gene therapy. Retinoblastoma is the commonest intraocular malignancy of childhood: leukocoria, strabismus, calcification; bilateral disease implies germline RB1 mutation and second tumour risk.
Worked example
A 2-year-old has a white pupillary reflex with a normal red reflex in the other eye. Reasoning: leukocoria is retinoblastoma until excluded, so examine both eyes, image for calcification and refer urgently; the differential includes congenital cataract, persistent hyperplastic primary vitreous, Coats disease and toxocariasis.
Traps
Missing retinopathy of prematurity screening dates; assuming a squinting child will outgrow it; forgetting genetic counselling for retinoblastoma families.