Higher order aberrations in a normal adult population

Purpose: To determine the distribution of Zernike coefficients and higher order aberrations in a normal population and its relationship with age, gender, biometric components, and spherical equivalent. Methods: During the first phase of the Shahroud cohort study, 6311 people of the 40-64-year-old population of Shahroud city were selected through random cluster sampling. A subsample of participants was examined with Zywave aberrometer (The Bausch & Lomb, Rochester, NY) to measure aberrations. Measurements of aberrations were done before cycloplegic refraction, and values generated from a minimum pupil diameter of 5 mm were reported in this analysis. Results: After applying exclusion criteria, 904 eyes of 577 people were analyzed in this study and mean age in this study was 49.5 ± 5.7 years and 62.9% were female. Mean root-mean-square (RMS) of the third, fourth, and fifth-order aberrations was 0.194 mm (95%CI: 0.183 to 0.204), 0.115 mm (95%CI: 0.109 to 0.121), and 0.041 mm (95%CI: 0.039 to 0.043), respectively. Total RMS coma (Z3 1, Z3 1 , Z5 1, Z5 1 ), Total RMS trefoil (Z3 3, Z3 3 , Z5 3, Z5 3 ), and spherical aberration (Z4 0 ) in the studied population was 0.137 mm (95% CI:0.129e0.145), 0.132 mm (95% CI: 0.123e0.140), and 0.161 mm (95%CI:0.174 to 0.147), respectively. Mean higher-order Zernike RMS in this study was 0.306 (95% CI: 0.295e0.318) micrometer, and in the multiple model, it significantly correlated with older age and short axial length. The highest amounts of higher-order RMS were observed in hyperopes, and the smallest in emmetropes. Increased nuclear opacity was associated with a significant increase in HO RMS ( p < 0.001). Analysis of Zernike coefficients demonstrated that spherical aberration (Z4 0 ) significantly correlated with nuclear cataract only (age-adjusted Coef ¼ 0.37 and p ¼ 0.012). Conclusion: This report is the first to describe the distribution of higher-order aberrations in an Iranian population. Higher-order aberrations in this study were on average higher that those reported in previous studies.