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L. A. Duffy, M. Day, D. Seidel, L. S. Gray, N. C. Strang; Modulation of Static Accommodation Responses in Emmetropes and Myopes by Peripheral Stimuli. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3921.
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© ARVO (1962-2015); The Authors (2016-present)
The aim of this study was to investigate the effect of peripheral stimuli upon the accuracy of the accommodation response in emmetropes (EMMs) and myopes (MYOs).
Twenty four (12 EMMs/12 MYOs) young, visually normal, subjects participated with informed consent in the experiment. Subjects viewed targets in real space at 25cm, monocularly, with the right eye and all MYO subjects were fully corrected using daily disposable soft contact lenses. Targets filled the entire visible field of view and consisted of a 4cpd sine wave grating within a central circular window, which was surrounded by a 0.5cpd sine wave grating. The junction between the two gratings was blurred with a Gaussian function. The radii of the central targets were varied randomly between 1, 2, 4, 8, 10, 16, 20deg. The experiment was then repeated using targets with a 0.5cpd sine wave grating centrally and a 4cpd sine wave grating peripherally. For each condition, the mean and standard deviation of 20 static accommodation responses was obtained from the right eye using an open view Shin-Nippon SRW-5001 autorefractor.
Mean accommodation responses (3.23±0.21D) were similar for all viewing conditions and both refractive groups. The mean standard deviation of the accommodation response of MYOs and EMMs showed no significant variation with the size of the central grating when the SF was 4cpd. When the SF of the central grating was 0.5cpd, the mean standard deviation of the accommodation response increased significantly for central target radii of ≥4deg (p<0.05). The increase in the variability was significantly larger in the MYOs compared to the EMMs (p<0.05).
Accurate accommodation response characteristics are maintained when sufficient detail is present within the centre of the target, regardless of peripheral information. In contrast, peripheral stimulation within 4 degrees can influence the variability of the static accommodation response when central stimulation is insufficient. The change in variability is more apparent in MYOs than EMMs and suggests that peripheral target features may have a role during the accommodation feedback control mechanism.
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