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The effect of bleach duration and age on the ERG photostress test

Wood, Ashley, Margrain, Thomas Hengist and Binns, Alison 2011. The effect of bleach duration and age on the ERG photostress test. Graefe's Archive for Clinical and Experimental Ophthalmology 249 (9) , pp. 1359-1365. 10.1007/s00417-011-1627-7

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Abstract

Background The ERG photostress test assesses the recovery of the focal 41 Hz ERG following exposure to a bright light that bleaches a significant proportion of photopigment. The aims of this study were: 1) to compare the repeatability of the ERG photostress test recovery time constant following long and short duration light exposure, and 2) to determine the effect of age on the ERG photostress test recovery time constant. Methods Focal 41 Hz ERGs were recorded from 23 participants (age range 20–71 years) at 20-second intervals for 5 minutes following either a short-duration (photoflash) or long-duration (equilibrium) light exposure. After a 5-minute wash-out period, the procedure was repeated using the second bleach modality. The time constant of cone recovery was determined by fitting an exponential model to the amplitude recovery data. The whole procedure was repeated on a second occasion. The co-efficient of repeatability (CoR) was calculated for each bleaching technique. The relationship between the time constant of recovery and age was investigated (Pearson’s correlation coefficient). Results The time constant of recovery following an equilibrium bleach was more repeatable than recovery following a photoflash (CoR = 85s and 184s respectively). Eight trials (from seven participants) failed to show a reduction in amplitude following the photoflash, suggesting that a blink or fixation loss had occurred. All participants were reliably light-adapted by the equilibrium bleach. For the equilibrium bleach data, the time constant of recovery increased with age at a rate of 27 seconds per decade. Conclusions The equilibrium bleach was more reliable and repeatable than the photoflash. Increasing participant age was shown to result in a lengthening of the recovery time constant, of a magnitude comparable to previously published psychophysical data.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Optometry and Vision Sciences
Subjects: R Medicine > RE Ophthalmology
Uncontrolled Keywords: Electroretinogram, ERG ; Cone adaptation ; Repeatability ; Age-related macular degeneration
Publisher: Springer-Verlag
ISSN: 0721-832X
Last Modified: 05 Jul 2019 21:30
URI: http://orca.cf.ac.uk/id/eprint/17378

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