Retinal image quality in myopic children undergoing orthokeratology alone or combined with 0.01% atropine

Background The retinal image quality derived from lower-order (LOA) and higher-order aberrations (HOA) for fixed 3-mm and photopic pupil diameters, in children undergoing combined 0.01% atropine and orthokeratology (AOK) versus those receiving orthokeratology alone (OK) over two years was evaluated. Methods The visual Strehl ratio based on the optical transfer function (VSOTF), derived from 2nd- to 4th-order terms (LOA and HOA combined), 2nd-order terms (LOA only), and 3rd- to 4th-order terms (HOA only) for fixed 3-mm and natural photopic pupil diameters, was compared between the two treatment groups. The individual Zernike coefficients for a fixed 3-mm pupil size of 2nd- to 4th-orders, root mean square (RMS) of LOA (Z(2)(0), Z(2)(-2), and Z(2)(2) combined), HOA (3rd to 4th orders inclusive), and Coma (Z(3)(-1) andZ(3)(1) combined) were also compared between the two groups. Results Right eye data of 33 AOK and 35 OK participants were analysed. Under photopic conditions, significantly lower VSOTF based on HOA only was observed in the AOK group compared with that in the OK group at all post-treatment visits (all P < 0.05); however, interactions between HOA and LOA resulted in comparable overall retinal image quality (i.e., VSOTF based on LOA and HOA combined) between the two groups at all visits (all P > 0.05). For a fixed 3-mm pupil size, the VSOTF based on HOA only, LOA only, or HOA and LOA combined, were not different between the two groups (all P > 0.05). AOK participants had slower axial elongation (mean +/- SD, 0.17 +/- 0.19 mm vs. 0.35 +/- 0.20 mm, P < 0.001), a larger photopic pupil size (4.05 +/- 0.61 mm vs. 3.43 +/- 0.41 mm, P < 0.001) than OK participants, over two years. Conclusions HOA profile related to an enlarged pupil size may provide visual signal influencing eye growth in the AOK group.