Central mfERG amplitude ratio as a predictor for visual outcome of macular hole surgery

To investigate whether visual acuity improvement achieved after surgical treatment for macular hole (MH) can be predicted by preoperative multifocal ERG (mfERG) central/peripheral amplitude ratio.

Thirty patients with unilateral MH were included. Evaluations with comprehensive ophthalmological examination including best-corrected visual acuity (BCVA) were performed at baseline and 1, 3, 8, 24 and 48 weeks after surgery, while mfERG (Diagnosys LLC; 61 hexagons-30°) and spectral-domain optic coherence tomography (sOCT-Heidelberg Engineering) were performed at baseline and 2 months after surgery. mfERG results are shown by means of the ratio between the amplitudes' average from rings 1 and 2 (central) and rings 4 and 5 (peripheral): the P1 ratio. mfERG data from 20 normally sighted age-matched subjects was used for comparison. A macular hole index (MH index) was defined as the quotient between hole height and base measured on OCT.

Twenty-six patients finished the 48-week follow-up. Mean ± SE (logMAR) preoperative BCVA was 0.93 ± 0.22 and improved in 0.25 ± 0.07 at 48 weeks. mfERG P1 ratio was reduced at baseline and increased significantly after surgery. A significant correlation was observed between preoperative P1 ratio and BCVA gain at week 8 (r = -0.42; P = 0.033). There was no significant correlation between preoperative MH index and postoperative BCVA (P > 0.05).

Retinal function assessed using the ratio between central and peripheral mfERG responses might be used as predictor of visual acuity outcome after macular surgery for MH.