Applicability of Electroretinography Measurements in Congenital PAX6-Related Aniridia

Congenital PAX6-aniridia is associated with ocular developmental abnormalities, including photoreceptor specification. We focused on characterizing retinal function by electroretinography (ERG) measurements and evaluated the usefulness of a handheld electrophysiology tool.

Patients underwent a comprehensive ophthalmological examination including best corrected visual acuity (BCVA) and full-field ERG measurements using the RETeval system with sensor strip skin electrodes. In addition to International Society for Clinical Electrophysiology of Vision (ISCEV) standards, photopic negative responses (PhNRs) were recorded.

Forty-one eyes of 21 patients (10 and 11 male patients, age = 25.3 ± 16.9 years, range = 9-60 years) from 16 families were included. BCVA ranged from light perception to 0.3 logMAR (mean = 1.02 ± 0.54) and exhibited greater impairment in older patients. Despite considerable variability in ERG amplitudes, no statistically significant difference was observed in ERG amplitudes between patients and controls (n = 18). However, implicit times (ITs) were significantly delayed (P < 0.001). Although PhNR response amplitudes and ITs were not significantly different from controls, W-ratio was considerably lower in patients (W = 0.89 ± 0.1) than in controls (W = 1.09 ± 0.05), indicating reduced signal transmission through the different layers of the retina. We observed an effect of glaucoma status causing even lower W-ratios (W = 0.94 ± 0.13 without confirmed glaucoma; and W = 0.88 ± 0.11 with treated glaucoma). ERG recordings were well-tolerated.

This is the largest ERG study conducted in congenital aniridia. Results show that both photoreceptor-related functions and postreceptoral signal transmission are affected in PAX6-related aniridia, suggesting retinal changes beyond the central macula. RETeval can serve as a useful instrument for the evaluation and surveillance of retinal function in aniridia, underscoring the potential risk of glaucoma.