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JS Werner, C Gerth; Optical and Neural Factors Mediating Senescent Changes in Multifocal Electroretinogram Responses . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1773.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the relative contribution of optical and neural factors to senescent changes in multifocal electroretinogram (mfERG) responses. Methods: MfERG responses were obtained from one eye of each of 71 normal phakic subjects (age 9-80 years) with the 7" stimulus-refractor unit (EDI) and VERIS ScienceTM 4.3 using the following protocol: bipolar contact lens, m-sequence =14, 103 hexagons, consecutive stimulation with 200 and 700 cd . m-2, pupils ≷ 6 mm, amplification 105, filter cut-offs at 10 and 300 Hz. Additionally, (A) 4 subjects were tested for a series of 9 stimulus intensities (50 - 700 cd . m-2) and (B) 3 subjects were tested with 6 different stimulus contrasts (48% to 99%). Spectral radiance was measured, converted to relative luminance and filtered by theoretical ocular media density spectra for subjects ages 25 and 75 years. First-order response density N1+P1 and latency P1 were analyzed. Results: Log mfERG response changes linearly as a function of age. Analyses of optical contributions to mfERG response were based on age-related changes in pupil diameter, ocular media transmission and stray light. The calculated change between 25 and 75 years are 0.15 log unit reduction (response density) and 0.0215 log unit increase (implicit time). The predicted changes due to age-related decreases in ocular media transmission [derived from (A)] and due to age-related increases in intraocular scatter [derived from (B)] are: 0.0511 and 0.009 decrease for log response density and 0.00492 increase and 0.024 decrease for log implicit time, respectively. Conclusion: Our data and analyses reveal contributions of both optical and neural factors to senescent changes in the mfERG. Optical factors, such as age-related reductions in retinal illuminance and increases in intraocular scatter, have a larger effect on response density than on implicit time.
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