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Omar Abdul Rahman Mahroo, Diana Kozareva, Talha Soorma, Alexander M Tanner, Ammar Yusuf, Haya Al-Ani, Christopher J Hammond; Does retinal neuronal processing slow with age? Photopic flicker electroretinograms from over 700 unrelated individuals. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1261.
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© ARVO (1962-2015); The Authors (2016-present)
Biomarkers of aging are of increasing interest; parameters relating to neural processing have potential utility in neurological assessment. Electroretinogram (ERG) responses are of increased latency in older individuals, but this may partly be explained by a smaller dilated pupil size reducing retinal illuminance of a given stimulus, and the effect of lens opacity. In this study, we explored ERG parameters when stimuli were adjusted according to pupil diameter to deliver a similar retinal illuminance.
Photopic 28.3 Hz flicker ERGs were recorded from volunteers from the TwinsUK cohort using a hand-held device (RETeval, LKC Technologies Inc., Gaithersburg, MD, USA) with skin electrodes and natural pupils. The device measured pupil diameter and adjusted stimulus strength to give a retinal illuminance of 85 Td s (background 850 Td), corresponding to the international standard photopic flicker stimulus delivered through a 6 mm diameter pupil. Recordings from right eyes were analysed, with not more than one twin from each pair included. Spearman correlation coefficients were calculated with age for amplitudes and peak times for the whole group, and for a subset under 40 years of age (in whom lens opacity was expected to be minimal).
Recordings were made from 1306 participants. Including only one twin per pair yielded 713 subjects (83% female; 93% North European ancestry). Mean (SD) age was 53 (16) years. Mean (SD) ERG amplitude was 27.1 (10.4) microvolts and peak time was 25.6 (1.6) ms. Correlation coefficients with age were -0.28 (p<0.0001) for amplitude and 0.35 (p<0.0001) for peak time. For participants under 40 (n=170), mean (SD) amplitude was 31.8 (11.6) microvolts and peak time was 24.7 (1.0) ms; correlation coefficients with age were -0.01 (p=0.88) for amplitude and 0.24 (p=0.0017) for peak time.
For the overall cohort, significant correlations emerged with age, suggesting that the effect is not attributable to changes in pupil diameter alone. Also, in the younger cohort, in whom lens opacity is likely to be minimal, a significant delaying of peak time with age was still seen. Taken together, the findings support a real age-related slowing of retinal cone system processing, as measured by the photopic flicker ERG peak time. Such rapid, non-invasive tests may provide useful neuronal aging biomarkers.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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