Mirror symmetry of peripheral aberrations for the eyes of iso- and aniso-myopes

Purpose : Peripheral optical quality is evaluated usually in only one eye of a person with the assumption that peripheral aberrations change similarly across visual fields of both eyes. Only one study has tested this assumption off-axis, and then only for a few angles along the horizontal field of isometropes. We investigate the assumption by measuring peripheral aberrations in both eyes of iso- and aniso-myopes across the field. \ud \ud Methods : Cycloplegic peripheral aberration for 5 mm pupils was measured at 39 locations across 42°x32° of right and left eye fields with a COAS-HD Hartmann-Shack aberrometer in 19 isomyopes [mean age 30±3 yrs; spherical equivalent refraction M (right/left): –2.2±1.9D/–2.4±1.9D] and 10 anisomyopes [29±6 yrs; M: –4.0±1.8D/–4.3±2.9D]. Isomyopes had interocular refraction differences <1.0D. Anisomyopes had interocular refraction differences between 1.0D and 2.6D. Pearson correlations of 2nd–4th order Zernike coefficients between the two eyes were determined at corresponding field positions e.g. temporal positions were compared. Orthogonal regression determined relationships between coefficients of the two eyes across the visual field. \ud \ud Results : Aberration coefficient patterns across the visual field changed similarly in both refractive groups as follows: quadratic rates of change for C(2,-2) & C(2,2), linear rates for C(3,1) and C(3,-1), and little change in C(4,0) and other 4th-order aberrations. Ignoring C(2,0), there were significant right-left correlations at >50% of field locations for C(2,2), C(3,-1), C(2,-2), C(4,0), C(3,1), C(4,-2) and C(4,2) in isomyopes and for C(2,2), C(3,-1), C(4,0), C(3,1), C(3,-3), C(4,-2) and C(4,2) in anisomyopes. The slopes of the correlation between right and left eyes in the orthogonal regression were not significantly different from either +1 for C(2,2), C(3,-1), C(3,-3), C(4,2) and C(4,4) or from –1 for C(2,-2), C(3,1), C(3,3) and C(4,-4)in isomyopes. For anisomyopes, the slopes were not significantly different from +1 for C(2,2), C(3,-1), C(4,0), C(4,2) and C(4,4) or from –1 for C(2,-2), C(3,1), C(3,3), C(4,-2) and C(4,-4).\ud \ud Conclusions : Aberrations were similar between eyes of iso- and aniso-myopes across the visual field for 2nd – 4th order coefficients. In a pooled data set, coefficients require sign changes for one eye. The slopes of the correlation show that most ocular aberrations are mirror symmetric between eyes about the vertical axis