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Carmen Canovas, Tim de Jong, Henk Weeber, Nomdo Jansonius, Patricia Piers; Head Stabilization Impact On Aberration Induction With An Adaptive Optics Visual Simulator. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3586.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the influence of head stabilization on wavefront aberration (WA) measurements and static WA induction with an adaptive optics visual simulator (AOVS).
A commercial AOVS (crx1, Imagine Eyes, Orsay, France), which allows for the measurement and induction of WA, was used. Measurements were performed on 6 right eyes from 6 subjects with paralysed accommodation. Three head stabilization methods were considered in this study: a commercial chinrest, a modified chinrest with an extra headband, and a bitebar. For each method, 3 WA measurements with no realignment were taken within one test (intra-test variability). The test was repeated three times with further realignment of the device and repositioning of the subject (inter-test variability). The procedure was performed at three different mirror states: (1) a flat mirror, without WA induction, and the induction of (2) -1D of horizontal astigmatism and (3) 0.13 microns of spherical aberration at 5mm. A control experiment with an artificial eye was also performed to establish the capabilities of the AOVS. All WA measurements were analysed at a 5mm pupil.
When the AOVS is used as a wavefront sensor, all head stabilization methods retrieve similar higher order RMS values for all subjects, without a clear trend in stability. The induction of low and higher order terms was both accurate and stable for the artificial eye as well as subjects, especially when the bitebar was used (Figure). The band added to the commercial chinrest did not improve stability.
An AOVS can either measure or induce both low and higher order aberrations in static mode. The head stabilization method does not impact the WA measurement, however when inducing aberrations, the bitebar adds stability necessary to reproduce the induced WA in a repetitive and accurate manner.
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