A 5-year-old boy is brought by his mother, who says his right eye turns inward. She first noticed it three months ago, mainly in the evenings and when he is tired or looking at nearby toys. In the mornings the eyes look straight. There is no double vision — he is too young to describe it — but his kindergarten teacher says he closes one eye when drawing. He was born full term, development is normal, and there is no family history of squint. He has never worn glasses and has not had an eye examination before.
Examination Findings
Visual acuity (Lea symbols): right 6/12, left 6/7.5. Cover test: at distance, a small right esotropia of about 10 prism dioptres; at near, a larger right esotropia of about 25 prism dioptres that increases when he looks at a small detailed target. Alternate cover test confirms a comitant deviation (same size in all gaze directions). With his mother’s spare +3.00 reading glasses held up in front of him as a rough trial, the near deviation reduces noticeably. Extraocular movements are full. Anterior segment is normal. Cycloplegic retinoscopy: right +5.00 DS, left +4.75 DS. Fundus examination is normal with no disc swelling. There is no ptosis, no nystagmus, and pupils react normally.
Investigations
Cycloplegic refraction is the key investigation and confirms significant uncorrected hypermetropia. No neuroimaging is indicated here: the deviation is comitant, onset is early childhood, and there are no neurological signs.
Questions to Think About
- Why does the inward turn get worse at near and when the child is tired?
- What is the role of the cycloplegic refraction in this case?
- If the deviation fully corrects with glasses, does the child still need surgery?
Diagnosis
Refractive accommodative esotropia secondary to uncorrected hypermetropia (+5.00 D), with early right amblyopia.
Reasoning
Reasoning: An esotropia that is larger at near than at distance, in a young hypermetropic child, points to accommodative esotropia. The child has about +5.00 D of uncorrected hypermetropia. To see clearly, he must accommodate (focus) strongly, and accommodation is neurologically linked to convergence (the near reflex triad). Each extra dioptre of accommodative effort drives extra convergence, pulling the eyes inward. When he is tired, his fusional control weakens and the latent deviation becomes manifest. The improvement with plus lenses during the trial confirms the mechanism: relaxing accommodation reduces convergence. The cycloplegic refraction is essential because a non-cycloplegic test underestimates hypermetropia in children — their powerful accommodation masks the true refractive error. Diagnosis: refractive accommodative esotropia with moderate hypermetropia. Management: typical management includes prescribing the full cycloplegic hypermetropic correction as constant wear — this usually straightens the eyes and treats the cause. The visual acuity of 6/12 in the right eye suggests early amblyopia, so amblyopia therapy (occlusion or penalisation of the better eye, per local protocol) is added after a period of glasses wear with refractive adaptation. Follow-up checks alignment with glasses, acuity, and binocular function. Surgery is not needed when glasses fully correct the deviation; it is considered only if a significant residual (non-accommodative) component remains. Parents are counselled that the glasses are treatment, not optional, and that the child will be reviewed regularly as the hypermetropia may reduce with eye growth.
Differential Diagnosis
- Non-accommodative (infantile) esotropia — ruled out: onset after infancy, deviation varies with fixation distance and improves with plus lenses, whereas infantile esotropia is large, constant, and present from the first months of life.
- Accommodative esotropia with high AC/A ratio — considered: the near deviation is larger than distance, but the deviation fully corrects with the hypermetropic correction, placing it in the refractive (normal AC/A) group rather than needing bifocals.
- Sixth nerve palsy — ruled out: the deviation is comitant (equal in all gazes) with full abduction, whereas a nerve palsy gives an incomitant esotropia worse on gaze toward the affected side.
- Intracranial pathology — no red flags here (no headache, vomiting, papilloedema, or neurological signs), so neuroimaging is not indicated.
Management
Full-time wear of the full cycloplegic hypermetropic correction; amblyopia therapy for the right eye after refractive adaptation; regular follow-up of alignment, acuity and binocularity; surgery only for any significant non-accommodative residual component.
Key Learning Points
- Uncorrected hypermetropia drives excess accommodative convergence — the classic mechanism of refractive accommodative esotropia in early childhood.
- Cycloplegic refraction is mandatory in children; without it the true hypermetropia is underestimated.
- When full hypermetropic correction straightens the eyes, glasses ARE the treatment — surgery is not indicated.
- Amblyopia commonly coexists and must be actively treated alongside the refractive correction.
- A deviation worse when tired or at near is a clue to an accommodative or intermittent mechanism.
Red Flags
- New-onset esotropia with headache, vomiting, or papilloedema — urgent neuroimaging to exclude intracranial mass.
- Incomitant deviation or limited eye movements — suggests nerve palsy or restrictive disease, not simple accommodative squint.
- Leukocoria (white pupil reflex) — always exclude retinoblastoma.
Educational content only — not medical advice. Clinical decisions must be made by a qualified professional for the individual patient.
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