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BA Blodi, K Stepien, M Altaweel, J Alexander, JN VerHoeve; Drusen Area is not Associated With a Depression of Macular Function as Assessed by the MERG . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1215.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare macular function assessed by multifocal electroretinogram (MERG) with baseline drusen area in a subset of patients in the Complications of Age-related macular degeneration Prevention Trial (CAPT). Methods: All patients had 10 or more large (≷125 u) drusen in each eye, no neovascular age-related macular degeneration (AMD), and a best corrected visual acuity of 20/40 or better, fulfilling the baseline eligibility criteria of the CAPT trial. MERGs were obtained from 34 eyes of 18 patients at the baseline (pretreatment) visit. Stereoscopic color fundus photographs were used to grade the area of drusen as a percentage of the area occupied within each of 3 concentric rings (subfields) in the macula: a central circle (500u radius), an inner ring (500 - 1500u radius) and an outer ring (1500 - 3000u radius). The MERG stimulus was a standard 103-element scaled hexagonal array subtending 22 degrees of the central macula. Recordings were obtained under binocular viewing conditions using an 8-min m-sequence with a base period of 13.3 ms. The amplitude and latency times of N1, P1, N2, and P2 waves were measured for the first-order kernel response and averaged within 3 concentric rings radiating from the fovea. The MERG rings corresponded closely to the subfields used in the drusen area analysis. The relationship between first order kernel MERG wave parameters from each ring average and the corresponding drusen area for that ring was assessed by separate Pearson product-moment correlations. Results: The drusen area varied in each subfield from 75% area covered by drusen. The correlation coefficient analysis revealed no statistically significant associations (all ps ≷ 0.07) between drusen area and the implicit time or the amplitude of any MERG first order kernel parameter recorded from the corresponding macular subfield (ring). Conclusion: Among 34 eyes with considerable variation in drusen area and MERG measures, drusen area was not associated with a depression of foveal, perifoveal or macular function as assessed by the MERG. This result suggests that large drusen in patients with non-exudative AMD do not preclude good macular function.
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