Peripheral aberration measurements: Elliptical pupil transformation and variations in horizontal coma across the visual field

摘要

Background: The aim was to determine the critical eccentricity at which two methods of elaborating peripheral wavefront measurements are significantly different and to characterise horizontal coma in healthy young adults. Methods: Peripheral aberrations were determined for 20 observers for central and eight peripheral gaze positions up to 20° using an IRX-3 aberrometer. In one subject, additional measurements up to 40° were obtained. Two definitions of stretching coefficients were compared. The raw empirical data were compared with theoretical modelling. Results: For both 3.5mm and 6.0mm pupils, no significant differences were observed between recalculated and non-recalculated elliptical pupils for both methods (p > 0.05) up to 20° eccentricity. For eccentricities greater than 20° and up to 40°, significant differences between circular and elliptical pupils at some eccentricities were apparent, which corresponded to theoretical models. Wide individual variations in horizontal coma across the peripheral field were observed. Conclusions: The data suggest that for eyes with average levels of aberrations, the elliptical transformation is of no practical importance for eccentricities up to 20°. In some cases the slope of horizontal coma was reversed compared with previous findings in normal eyes. © 2011 Optometrists Association Australia.