Early structural and functional retinal changes in intermittent exotropia
Reviewed by Fiona Rowe

This study aimed to evaluate and compare spectral domain optical coherence tomography (SD OCT) and electrophysiological measures in patients with intermittent exotropia and healthy controls, to outline changes in retinal and optic nerve structure and function. This was a cross-sectional study of 52 patients (26 intermittent exotropia and 26 controls) with 50% male / females in each group. Mean age for exotropia was 9.23 years and controls were aged 11–20 years. Refraction for exotropes was a range of -0.75D to +1.00D. All had 6/6 best corrected visual acuity and all had binocular single vision. None had amblyopia. Mean angle of deviation for intermittent exotropia was 32.50PD (range 25–40) and all had good control. On multifocal electroretinogram (mERG), P and N wave latency were significantly prolonged for intermittent exotropia vs controls with significantly lower amplitudes in the P and N waves. On pattern ERG, the P50 wave amplitude was significantly lower and N95 wave latency was significantly prolonged for the intermittent exotropia group. There were no interocular differences for either group. On OCT, the upper and lower ganglion cell complex and upper retinal nerve fibre layer were significantly thinner in exotropia. There was a significant positive correlation only with the P wave amplitude in ring 4 and amplitude of N wave in rings 1 and 3. The authors concluded that strabismus alone could cause reduction in mERG waves. They reflect that retinal thickness findings were not sufficient to be significant as an indication of whole retinal thickness. Ganglion cell complex thinning, coupled with pERG responses suggest ganglion cell complex is affected which potentially indicates early-stage dysfunction of ganglion cells. This requires long-term follow-up to validate this hypothesis. None of the observed changes were clinically significant and the authors acknowledge their small sample size.

Evaluation of structural and functional retinal changes in children with intermittent exotropia vs healthy children.
Ebeid WM, Abdellatif MK, Samak NM.
JOURNAL OF PEDIATRIC OPHTHALMOLOGY AND STRABISMUS
2024;61(5):317–24.