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K. M. Hampson, S. S. Chin, E. A. H. Mallen; Correction of Aberration Dynamics Modulates Closed-Loop Accommodation Responses in a Time Dependent Manner. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1789.
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Khosroyani and Hung have proposed a pre-programmed component within the control system for accommodation responses to dynamic stimuli (Bulletin of Mathematical Biology, 64, 2002). Manipulation of aberration dynamics during the accommodation response has been shown to adversely affect focusing accuracy in some subjects. Currently, the exact role of aberration dynamics in accommodation control, and the temporal location of information gathering necessary to drive the accommodation response is not known.
We used an adaptive optics (AO) system to manipulate the aberrations in closed-loop of five subjects at various temporal locations in their response to a plus or minus 0.75 D step. The AO system comprises two sensing channels, allowing direct measurement of the ocular aberrations to occur independent of the deformable mirror. The target was a Maltese cross at an accommodation level of 2 D illuminated by monochromatic light (510 nm). Aberrations were corrected either: A) before the step, B) after the step, C) before and after the step, D) during the accommodation response latency period (after the stimulus change, but before an accommodation response), or E) after the response latency period.
The results were subject dependent. The most significant effect on accommodation was a reduction in response gain. This effect was greatest when the aberration correction was applied during the response latency period (condition D).
These data suggest that the accommodation system primarily utilises information derived from the aberration dynamics during the response latency period to guide closed-loop responses.
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