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Patricia Grant, Justin M. Wanek, Ruth Zelkha, Jennifer I. Lim, Mahnaz Shahidi; Wavefront Aberration and Fixation Variations in Normal Subjects. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4460.
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Accuracy and efficiency in the correction of wavefront aberrations are important for optimal assessment of optical quality of the eye and improved retinal imaging. It is has been previously established that some subjects with retinal diseases have increased wavefront aberrations, reduced fixation stability, and/or are eccentric viewing. The purposes of this study were to establish a normal baseline for wavefront aberrations at different retinal eccentricities before and after adaptive optics (AO) correction and determine the relationship between wavefront aberration and fixation variations.
Wavefront aberrations were measured in 12 visually normal subjects (47 ± 15 years) with the use of an AO retinal imaging system before and after wavefront error correction. The root mean square (RMS) of the wavefront error for high order (HO) and total aberrations was calculated at 7 retinal eccentricities, within 5 degrees nasal and temporal to the fovea, and for pupil diameters greater than 4 mm. The RMS wavefront error variability was determined based on the standard deviation of repeated measurements. Fixation variability was quantified based on AO retinal images by measuring the x and y displacement of selected retinal features between images. Analysis of variance and linear regression analysis were performed on the data.
Total and HO RMS measurements were similar among locations at different retinal eccentricities before and after AO correction (p > 0.7). Variability of repeated measurements of total and HO RMS was also independent of retinal location (p > 0.4). There was a statistically significant reduction in total and HO RMS wavefront error with AO correction at all retinal eccentricities (p < 0.003). Fixation variability was largest at the fovea and 5 degree temporal to the fovea, but was not significantly different among locations at different retinal eccentricities (p = 0.3). HO RMS wavefront error variability and fixation variability were linearly correlated (R = 0.8; p = 0.005).
The findings on normal baseline measurements of RMS wavefront error and fixation variability are useful for future studies aimed at the improvement of retinal imaging and visual performance of subjects with retinal pathologies.
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