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Yue Shi, Hope M. Queener, Raymond A. Applegate; Stochastic Parallel Gradient Descent Used To Optimize Retinal Image Quality For Highly Aberrated Eyes Given Uncertainty Of The Wavefront Guided Correction Alignment. Invest. Ophthalmol. Vis. Sci. 2012;53(14):161.
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© ARVO (1962-2015); The Authors (2016-present)
Dynamic movement (e.g., contact lens) or a fixed displacement (e.g., corneal implants, refractive surgery) of a full wavefront guided correction with respect to underlying wavefront error (WFE) inevitably decreases retinal image quality (RIQ). To improve the RIQ in the presence of fixed or dynamic misalignment a partial correction may be optimal. The purpose of this study is to search for partial corrections which provide better RIQ for highly aberrated eyes given uncertainty in correction placement using a stochastic parallel gradient descent algorithm (SPGD).
WFE measurements over a 5mm pupil of 3 mild and 3 moderate keratoconic (KC) eyes were randomly selected from our database. A discrete 3 point rotation misalignment pattern was modeled: 5 degrees counterclockwise, 0 degrees and 5 degrees clockwise. RIQ was quantified using log visual Strehl (log VS) and in turn used to predict visual acuity gain or loss (change of log VS = -2.237 * change of logMAR acuity, Ravikumar et al. 2011) in order to compare 3 correction modes: 1) a conventional correction, 2) 4th radial order full magnitude correction and 3) the SPGD optimized 4th radial order partial magnitude correction.
For each of the 3 mild and 2 out of 3 moderate KC WFEs, the SPGD optimized corrections provided a significant improvement (paired t-test, p=0.05) in RIQ over conventional corrections and 4th order full magnitude corrections. The gain in RIQ led to a predicted average of 5.20±1.06 and 5.77 ± 3.15 lines improvement in logMAR acuity over the conventional corrections for 3 mild eyes and 3 moderate eyes respectively. The gain in RIQ led to a predicted average of 0.68 ± 0.18 and 0.98 ± 0.40 lines improvement in logMAR acuity over the 4th order full magnitude corrections for 3 mild eyes and 3 moderate eyes respectively.
The SPGD optimized corrections improved RIQ for highly aberrated eyes in the presence of rotation errors. Future studies will extend the alignment errors to represent realistic misalignments (translation and rotation) of correcting modalities based on probability distributions of the likely alignment errors.
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