The enhanced S-cone syndrome in children

The enhanced S-cone syndrome (ESCS), a retinal degenerative disease often associated with NR2E3 mutation,1–4 is due to increased numbers of S-cones at the expense of other photoreceptors or miswiring distal to the photoreceptors.5 Adults complain of hemeralopia, and are diagnosed from their unique retinal and electroretinogram (ERG) findings1–4—characteristic deep clumped pigmentary deposition around the vascular arcades;1–4 varying degrees of retinoschisis,1–4 a similar, simplified and delayed ERG waveform response to flashes under photopic and scotopic conditions;2,3 and a delayed 30-Hz flicker ERG amplitude lower than that of the photopic a-wave.2,3 Paediatric ESCS and its differing clinical features is the subject of this report.

Case series

Three children were evaluated because of inward eye turn and poor night vision noted since approximately 2 years of age. Retinal examination (fig 1) and cycloplegic refractions were performed 40 min after cyclopentolate 1% drops. NR2E3 was directly sequenced1 from venous blood samples. ERGs, performed under chloral hydrate sedation and according to the recommendations of the International Society for Clinical Electrophysiology of Vision,3 were consistent with ESCS (fig 2). Family history was significant only for case 1.