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C. Gerth, P.B. Delahunt, S. Alam, L.S. Morse, J.S. Werner; Cone–Mediated Multifocal ERG Responses in Early Stage AMD: Significant Progression Over a Long– Term Follow–Up . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1585.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Morphology and visual function in early age–related macular degeneration (AMD) is known to progress over time. The cone–mediated multifocal electroretinogram (mfERG) is a sensitive tool to determine localized changes in early AMD. We tested whether significant mfERG changes in patients with large drusen were progressing over a long–term follow–up. Methods: Seventeen eyes of fourteen patients with large drusen were re–evaluated after 28 to 41 months (mean 31 months). Best–corrected visual acuity (VA) was checked with the ETDRS chart. Fundus images were graded and compared to the baseline. MfERG were recorded with a stimulus–refractor unit (frame rate 75 Hz) (VERISTM 4.8) using the following protocol: bipolar contact lens, m–sequence =14, 103 hexagons, Luminance: 200 cd . m–2, pupils > 6 mm, amplification 105, filter cut–off's at 10 and 300 Hz. Each of the 103 first–order kernel responses was analyzed for implicit time (N1, P1, N2) and response density (P1–N1) and compared to age–matched normal controls and to the baseline measurement. Results: VA was stable in 12/17 eyes, and dropped in 3/17 and 2/17 eyes for 1 or 2 lines in the ETDRS chart, respectively. None of the eyes showed a change in the AMD level specified by fundus photos. MfERG revealed abnormal response densities (in 10.8% of all tested retinal areas) and implicit times N1, P1 and N2 (in 12.7%, 11.0%, 10.8% of all tested retinal areas; respectively). The localized comparison of the baseline and follow–up mfERGs revealed significant changes more often in response density P1–N1 than in implicit times N1 and P1. Longitudinal mfERG changes were more often detected within the central 15 degrees than outside of 15 degrees. Conclusions: Cone–mediated retinal function in early AMD progresses despite stable visual acuity and AMD level. The functional progression is observed as a global retinal deterioration.
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