Leukocoria and retinoblastoma: Viva

This is a branching oral built to probe the reasoning that holds the red reflex test and the urgent referral at the centre, the RB1 two-hit biology and the International Intraocular Retinoblastoma Classification, and to expose the candidate who has memorised the headline without the safety-critical corners. The questions escalate from the framing to the red reflex test, the molecular biology, the treatment pathway and the heritable disease, with deliberate probes into the trilateral retinoblastoma and the global disparity. ^[1]

Opening question: framing the problem

The examiner opens with the white glow in the photograph and asks: how do you frame this problem in a single sentence, and what is your first step? ^[1]

A strong answer names the leukocoria as retinoblastoma until proven otherwise, confirms the finding with the red reflex test, and states that the first step is the same-day referral to the ophthalmology service. ^[1][2]

Model answer. This child has leukocoria, the white pupillary reflex, and it is retinoblastoma until proven otherwise. The first step is to confirm the finding with the red reflex test in the dim room and to refer the child the same day to the ophthalmology service, because the delay of weeks can convert the curable intraocular tumour into the lethal extraocular disease. ^[1]

Probe one: the red reflex test

The examiner presses: describe the red reflex test, and tell me what is abnormal. ^[1]

A strong answer describes the technique and the interpretation. The test is performed in the dim room with the direct ophthalmoscope held close to the examiner's eye at thirty centimetres from the child, with the ophthalmoscope at the zero or a low dioptre, and the light is shone at both pupils simultaneously while the examiner compares the colour and the brightness of the reflex in the two eyes. The normal reflex is the warm orange-red, symmetric and filling the pupil. The abnormal reflex is the white, the yellow-white, the asymmetric or the absent, and any abnormality demands the urgent referral. The test is performed at the newborn examination, at the six-week check and at every well-child visit. ^[1][2]