Paediatric eye examination and red-reflex assessment — formative SAQs

SAQ 1 (10 marks)

A six-week-old infant is brought for a routine check. The red-reflex test shows a dense white reflex in the right eye and a normal red reflex in the left. The parents had not noticed anything and feel the baby sees normally. [4]

Question: (a) Describe the correct technique for the red-reflex test and explain the physiology of the normal reflex. (b) Give a prioritised differential diagnosis for this finding and state the immediate management. (c) Outline how you would communicate the result to the parents. (10 marks) [4] [6]

Model answer

(a) Technique and physiology (3 marks). Perform the test in a dim room, with the direct ophthalmoscope on the largest, brightest spot at zero or low magnification, standing about an arm's length away (roughly 30 to 45 centimetres), and examine both pupils together so the two reflexes can be compared side by side (the Bruckner test); repeat at a couple of distances and gaze positions and document the finding for each eye. The normal orange-red reflex is light that has passed through the clear cornea, aqueous, lens and vitreous, reflected off the retina and the blood-rich, melanin-rich choroid, and returned through the same clear media — so the reflex tests the clarity of the whole visual axis. [4] [1]

(b) Differential and immediate management (5 marks). A dense white reflex in an infant is leukocoria, a pale lesion in the visual axis reflecting light back white. The differential is led by the two that threaten sight or life: congenital or developmental cataract (common, treatable, time-critical for amblyopia) and retinoblastoma (the primary intraocular malignancy of childhood, which can be fatal beyond the eye). Next come persistent fetal vasculature (a fibrovascular stalk and retrolental mass, usually unilateral and microphthalmic from birth), Coats disease (exudative retinal detachment from retinal telangiectasia), ocular toxocariasis, retinal detachment (including from trauma or shaken-impact injury) and retinal or choroidal coloboma. The immediate management is urgent ophthalmology referral, the same day for a suspected serious lesion; apply no drops, ointment or home remedy before specialist review; document the finding for each eye; and arrange the dilated fundus examination, ultrasound for calcification, and examination under anaesthesia as the ophthalmology team directs. Do not order blood tests in lieu of referral. [3] [6]

(c) Communication (2 marks). Explain the urgency in plain language without using alarming diagnostic labels — frame it as an abnormal screening finding that needs an eye specialist to look at today, not as a suspected tumour. Tell the parents exactly when and where to be seen, what the specialist will do (dilate the pupil and examine the back of the eye), what would bring them back sooner, and the safety-net of confirming the appointment was kept. Avoid the dual pitfalls of false reassurance ('it is probably nothing') and premature labelling ('this could be cancer'). [4] [6]

SAQ 2 (10 marks)

A three-year-old attends a preschool vision screen. The red reflex is clearly darker in the left eye than the right, with no white reflex, and the cover test reveals a left esotropia. The child otherwise looks well. [4]

Question: (a) What does the asymmetric red reflex indicate, and what is the mechanism? (b) Outline the further assessment and the role of instrument-based screening in this age group. (c) Discuss the management, follow-up and prognosis. (10 marks) [4] [10]

Model answer

(a) Meaning and mechanism (3 marks). An asymmetric reflex in which one side is darker (but present, not white) is the Bruckner sign of anisometropia or strabismus — here confirmed by the left esotropia. The mechanism is that the darker eye is the one out of focus or turned, so less of the returning light is captured. Anisometropia (a difference in refractive error between the eyes) and strabismus are both amblyopia risk factors: during the sensitive period the brain suppresses the blurrier or misaligned image, producing amblyopia that becomes harder to reverse. This is an abnormal screening result that needs ophthalmology referral, though for a refraction and motility assessment rather than an urgent mass workup. [4] [11]

(b) Further assessment and instrument-based screening (3 marks). Complete the age-adapted vision assessment: monocular distance acuity with matching optotypes such as HOTV or LEA symbols, applying the AAPOS age-specific referral thresholds, and a stereopsis test (Randot or Titmus), which is a sensitive marker of strabismus or amblyopia. Instrument-based screening (photoscreening or handheld autorefraction, such as the Spot or Plusoptix devices) captures an image and flags amblyopia risk factors from refractive error, pupil size and media clarity; it is endorsed from about one to three years of age and validated against the AAPOS referral criteria, and it remains useful in the pre-preschool child who cannot yet reliably match symbols. Exclude the technical false causes (a lit room, wrong distance, high myopia) by repeating the test correctly. [7] [10]

(c) Management, follow-up and prognosis (4 marks). Refer for ophthalmology assessment for a cycloplegic refraction and a full motility and fundus examination; definitive management is cause-specific and belongs with ophthalmology — glasses for refractive error, and amblyopia therapy with patching or atropine penalisation of the better-seeing eye. Follow up the child through ophthalmology to monitor acuity and alignment. The prognosis of amblyopia is good when detected and treated during the sensitive period in the preschool years, and early screening has been shown to lower both the prevalence and severity of amblyopia — which is the evidence base for screening preverbal and preschool children. A previously normal child who develops a new squint or a new asymmetric reflex is re-referred urgently. [11] [9]