Higher order aberrations and axial elongation in combined 0.01% atropine with orthokeratology for myopia control.

Abstract

To compare the changes in higher order aberrations (HOA's) for photopic and mesopic pupil diameters in children undergoing orthokeratology treatment (OK) or combined 0.01% atropine with orthokeratology treatment (AOK), and their association with axial elongation. Children aged 6 to <11years with 1.00-4.00 D of myopia were randomly assigned to each treatment group. Photopic and mesopic pupil diameters were quantified using automated pupillometry and HOA's were measured with a Hartmann-Shack aberrometer and Badal system to control for accommodation. HOA's were rescaled to photopic and mesopic pupil diameters and fitted with a 6th order Zernike polynomial expansion. Axial length was measured using an optical biometer under cycloplegia. Baseline and six-month data from 25 AOK and 28 OK participants were analysed. At the six-month visit, pupil diameter was larger in the AOK group under photopic conditions (3.70±0.42 vs 3.12±0.33mm, p<0.001), along with a range of HOA metrics [3rd to 6th order and higher order root mean square error values (HO RMS), all p≤0.003] and individual Zernike terms (primary spherical aberration, and oblique quadrafoil, both p≤0.03). Axial elongation was greater in the OK treatment group (0.05±0.08 vs -0.01±0.12mm, p=0.02). In the AOK group, axial elongation was correlated with the increase in photopic pupil diameter (r=-0.45, p=0.02) and with several HOA metrics; however, these associations were not observed in the OK group. AOK treatment resulted in increased photopic pupil size and HOA's, and significantly less axial elongation over a six-month period compared to OK treatment alone. The improved myopia control observed with combination 0.01% atropine and orthokeratology may be a result of an enhanced optical effect due to a larger photopic pupil size.