Distribution and enantiomorphism of higher-order ocular optical aberrations

Objective: To characterize and investigate the higher-order optical aberrations (HOAs) and their distribution and symmetry between both eyes (enantiomorphism).

Methods: Wave-front measurements were taken using Hartmann-Shack aberrometry and Zernike polynomial terms reconstruction of the total ocular wave front. Optical aberrations were quantitatively analyzed using the RMS (root mean square) Zernike coefficient term value. Symmetry between both eyes was assessed for each aberration according to two criteria: the RMS coefficient value and aberration magnitude.

Results: Sixty patients were included in the study. The HOAs presenting the highest magnitude were fourth-order spherical aberration (Z40; M=0.3038 microm), primary coma (Z31; magnitude M=0.2285 microm) and trefoil (Z33; M=0.1870 microm). A significant mirror symmetry between both eyes was present for high-order aberration orientations. Considering the magnitude of each aberration, symmetry was present in seven of eight aberrations (all but primary coma). HOAs were higher for ametropes than emmetropes. The hyperoptic eyes had more spherical aberrations than myopic and emmetropic eyes.

Conclusions: Symmetry between the right and left eye is a less common characteristic of HOAs. The difference in the mean age of the studied population may account for the differences in the total high-order and spherical aberration levels found in our study.