Recognising an absent red reflex and the urgency of congenital cataract — OSCE

Candidate instructions (8-minute station)

You are the paediatric registrar in clinic. A 4-week-old term infant is brought by his first-time parents because the child-health nurse thought the left pupil looked white in a photograph. You perform a red-reflex test and find the left reflex absent; the right is a normal orange-red. [11]

Your tasks, each grounded in the evidence below, are: [11]

1. Confirm and explain the finding, and explain why an absent or white reflex is urgent — naming the cannot-miss diagnosis and the reason for speed. [12]
2. Outline the definitive management and the surgical time-window for a dense unilateral congenital cataract, in language the parents can follow.
3. Explain the aphakia-versus-intraocular-lens decision and what the Infant Aphakia Treatment Study showed, so the parents are prepared for the ophthalmology discussion. [7]
4. Explain the lifelong glaucoma surveillance the child will need, and why the operation is the start of treatment. [5]

Examiner brief (not shown to candidate)

A strong candidate will: perform and correctly interpret a red reflex (dim room, ophthalmoscope at arm's length, +0 to +2 D, both pupils compared); state that a white/absent reflex is same-day/urgent referral because retinoblastoma cannot be excluded and the unilateral critical period (first 6 to 8 weeks) is closing; give the surgical window of by about 6 weeks for a dense unilateral cataract; summarise the IATS as aphakia + contact lens equals primary IOL for acuity but with fewer reoperations and less glaucoma; and explain that aphakic glaucoma is common, silent and late, demanding lifelong pressure checks, with patching compliance the single biggest modifiable determinant of final acuity. [5]

Marking domains

Model parent-facing explanation (for self-assessment)

"I'm glad the nurse sent you in. On the red-reflex test — where I shine a light from about an arm's length and look for the orange glow in each pupil — your baby's right eye has a normal glow and the left has no glow at all. That tells me there is something blocking the light at the lens, which is most likely a cataract. The reason I won't wait is two-fold: first, the same sign can be caused by a tumour at the back of the eye called a retinoblastoma, and the eye doctor needs to look today or in the next day or two to rule that out; and second, because a baby's brain is still learning to see, a cataract blocking one eye for even a few more weeks can permanently weaken the vision pathway from that eye — so if it is a cataract, the operation is done within weeks, ideally before he is about six weeks old. [11]

"At that operation the cloudy lens is removed. In a baby this small the surgeon usually leaves the eye without a lens and corrects the focus with a contact lens, because a large study showed that implanting an artificial lens at this age does not improve the vision but does raise the chance of further operations and of a pressure problem called glaucoma. The most important thing to understand is that the operation is the beginning of treatment, not the end: he will need the vision pathway strengthened by patching the good eye for some hours each day, glasses or a contact lens, and regular checks of the eye pressure for the rest of his childhood, because glaucoma can quietly develop years later even when the operation went perfectly." [5] [7]