Impact of contact lens materials on the mfERG response of the human retina.

Abstract

To investigate the effect of different hydrophilic and rigid gas-permeable contact lens (CL) materials on multifocal electroretinography (mfERG). The mfERG was recorded in 18 healthy subjects with RETI-port/scan21™: 11 subjects underwent mfERG recording wearing two different hydrophilic CLs with different water contents in a randomized order (1 silicone hydrogel-Comfilcon A, 48%EWC, and 1 hydrogel-Omafilcon A, 62% EWC) and 7 other subjects wore a hydrophobic rigid gas-permeable scleral lens (SL)-Hexafocon A. Control measures were recorded without CL in both groups. mfERG recordings were performed with a stimulus array pattern of 103-scaled hexagons displayed on a 19-inch RGB monitor at 28cm distance at a frame rate of 60Hz. The amplitude (nV), implicit time and response density (nV/deg2) of the first-order kernel components N1, P1 and N2 were evaluated for the total mfERG response and for the response averages of 4 quadrants and of 6 successive concentric rings. Subjects were optically corrected for the working distance of ERG display. Hydrophobic material significantly decreased the P1 amplitude of the total mfERG response, at Rings 3, 4 and 6 and Quadrant 4 (> 53.77 ± 43.2nV; P ≤ 0.050), as well as the total (- 71.59 ± 50.68nV) and Ring 6 (- 104.76 ± 79.88nV) N2 amplitude (P ≤ 0.043). N1, P1 and N2 peak times suffered significant changes with both hydrophilic CL (P ≤ 0.050). Omafilcon A significantly increased P1 amplitude of Ring 5 and N2 amplitude of Ring 4, when compared to baseline (52.40 ± 71.87nV; P = 0.036) and to Comfilcon A (39.51 ± 48.63nV; P = 0.023), respectively. Hydrophobic CL slightly attenuated the strength of the mfERG signal, especially at the middle to peripheral retinal areas, while hydrophilic CL slightly changed the implicit time of the response. Different hydrophilic CL materials might affect the mfERG response differently. When considering the measurement of mfERG obtained with a CL in place, researchers should bear in mind that some changes can be related to CL material.