Abstract
Background: In adults, higher order aberrations (HOAs) vary during accommodation [1] which reduces retinal image quality [2]. These changes may provide a mechanism linking near work and myopia development [3], however little is known about HOAs during accommodation in children.
Methodology: HOAs of 90 children (mean age and spherical equivalent refraction: 8.2 ± 1.8 years; +0.63 ± 0.34 D) were measured at four accommodation demands (0, 3, 6 and 9 D) using a Hartmann-Shack aberrometer (COAS-HD). Individual Zernike term coefficients up to and including the 6th-order were analysed over a 4 mm pupil at each accommodation demand. Root mean square (RMS) errors were calculated for total (2nd–6th orders), higher order (3rd–6th orders) (HO), individual radial orders, coma (Z[3,-1], Z[3,1], Z[5, −1] and Z[5,1]), trefoil (Z[3, −3], Z[3,3], Z[5, −3] and Z[5,3]) and spherical aberration (Z[4,0] and Z[6,0]) (SA). Visual Strehl ratios based on the optical transfer function were determined from HOAs (VSOTF).
Results: Total, HO, all individual orders, coma, trefoil, and SA RMS varied significantly with accommodation demand (p < 0.0001), as did several individual Zernike terms and the VSOTF (p < 0.0001). The change in the VSOTF from 0 D was 0.002 ± 0.067 (p = 1.000), −0.024 ± 0.098 (p = 0.451), and −0.147 ± 0.188 (p < 0.0001) at 3, 6 and 9 D, respectively.
Conclusions: HOAs changed significantly during accommodation resulting in a significant reduction in retinal image quality at the 9 D accommodation demand. Longitudinal studies are required to examine the potential influence of these changes on eye growth.
The authors wish to acknowledge Pryntha Rajasingam for her assistance during data collection.