Photoreceptor dysfunction in early and intermediate age-related macular degeneration assessed with mfERG and spectral domain OCT.

Abstract

To evaluate the changes of the photoreceptor layer (PRL) thickness with spectral domain optical coherence tomography (SD-OCT) and the retinal function by mfERG, as well as the correlation of morphology and function parameters in subjects with early and intermediate age-related macular degeneration (AMD). Subjects with clinical diagnosis of early or intermediate AMD and age-matched healthy subjects were recruited prospectively in this study. Color fundus photography, SD-OCT, and mfERG were conducted. Retinal photoreceptor thickness was measured, and first-order kernel responses were recorded. The differences between AMD group and control group were compared, and the correlations between macular photoreceptor thickness and the mfERG were analyzed. PRL thickness (μm) in four areas including foveola and 0.5, 1.5, and 3 mm away from foveola was 192.48 ± 17.37, 163.73 ± 12.95, 130.93 ± 9.20, and 108.78 ± 7.81, respectively, in normal eyes, whereas in AMD group, they were 158.61 ± 45.25, 138.91 ± 20.92, 118.91 ± 12.85, and 95.00 ± 9.64, respectively (P < 0.001). The mean amplitude response densities of AMD patients decreased significantly compared to the control group in ring 1-6 (P < 0.001). The mean mfERG N1 and P1 latency of AMD patients prolonged compared to the control group, except the ring 1 (P = 0.588 and P = 0.084). The macular PRL thickness was significantly associated with the mfERGN1 and P1 amplitude density in ring 1-4 (r = 0.338-0.533, P < 0.01). PRL thickness decreases are in accordance with the deterioration of retinal electrophysiological activity. The retinal PRL thickness is important parameter to assess of early and intermediate AMD severity.