Influence of higher order aberrations and retinal image quality in myopisation of emmetropic eyes

Refractive error, higher order aberrations (HOA), axial length (AL), anterior chamber depth (ACD) and average corneal radius of curvature were measured after cycloplegia from 166 emmetropic participants at the Sydney Myopia Study (SMS, 2004-2005, age 12.63 ± 0.48 years). Measurements were repeated approximately 5 years later at the Sydney Adolescent Vascular and Eye Study (SAVES, 2009-2010, age 17.08 ± 0.67 years). The baseline spherical equivalent (M) did not differ significantly between the participants lost to follow-up (65%) and the participants enrolled in SAVES study (p = 0.932). Refractive error and HOA were measured using a Shack-Hartmann aberrometer for a pupil diameter of 5 mm and AL, ACD and average corneal curvature measured using IOL Master at both visits. Retinal image quality in terms of Visual Strehl ratio (VSOTF) for a 5 mm pupil diameter was determined using on-axis lower and HOA. General linear model was used to determine the association of HOA and retinal image quality with change in refraction. Of the 166 emmetropes, 41 (25%) had myopic change (change in M > -0.50 D) and 125 (75%) had no change in refraction (change in M between +0.49 D and -0.49 D). Change in C[4, 0] (p < 0.001, R² = 0.236), fourth order RMS (p = 0.003, R² = 0.097) and coma RMS (p = 0.004, R² = 0.056) from baseline were significantly correlated with change in refraction. More positive change in C[4, 0] was associated with lesser myopic change in refraction. The eyes with myopic change in refraction decreased in positive C[4, 0] (at baseline = +0.049 ± 0.05 μm, at follow-up = +0.024 ± 0.05 μm, p < 0.05). In comparison, eyes with no change increased in positive C[4, 0] (at baseline = +0.033 ± 0.04 μm, at follow-up = +0.047 ± 0.04 μm, p < 0.05). Thus in conclusion, no significant association was observed between HOA and retinal image quality at baseline and development and progression of myopia among emmetropic eyes. The change in spherical aberration (C[4, 0]) with myopic change is possibly associated with changes occurring in crystalline lens during ocular growth.