Longitudinal changes in axial length in high myopia: a 4-year prospective study

Aim To determine the longitudinal changes in the axial length (AL) in patients with high myopia without any other ophthalmic disease Methods Participants were divided into two groups: a high myopia group (60 eyes) without myopic degeneration, such as chorioretinal atrophy or posterior staphyloma, and a control group (60 eyes). Both groups were further divided into subgroups according to the AL: subgroup 1 (≥27.5 mm), subgroup 2 (26.0–27.5 mm), subgroup 3 (24.5–26.0 mm) and subgroup 4 (<24.5 mm). The ALs were measured five times at 1-year interval using an IOL master, and the AL was fitted with linear mixed models. Results In the high myopia group, the AL showed a relatively constant increase at each visit, and they were significantly different with previous measurements at most visits, whereas the control group showed no significant change of AL. Subgroups 1,2 and 3 showed significant changes in AL over time (0.064, 0.032 and 0.012 mm/y, respectively). In univariate analyses, age, best-corrected visual acuity, baseline AL and anterior chamber depth were significantly correlated with changes in the AL in the high myopia group. In multivariate analysis, only baseline AL remained significant (p<0.001). Conclusions Myopic eyes, including moderately myopic eyes, showed a consistent increase in AL over 4 years, and eyes with a longer baseline AL showed a greater increase in AL than eyes with a shorter AL.