Limited change in anisometropia and aniso-axial length over 13 years in myopic children enrolled in the Correction of Myopia Evaluation Trial

Abstract

Purpose: We investigated changes in anisometropia and aniso-axial length with myopia progression in the Correction of Myopia Evaluation Trial (COMET) cohort.

Methods: Of 469 myopic children, 6 to <12 years old, enrolled in COMET, 358 were followed for 13 years. Cycloplegic autorefraction and axial length (AL) in each eye were measured annually. The COMET eligibility required anisometropia (interocular difference in spherical equivalent refraction) of ≤ 1.00 diopter (D). For each child, a linear regression line was fit to anisometropia data by visit, and the regression slope b was used as the rate of change. Logistic regression was applied to identify factors for significant changes in anisometropia (b ≥ 0.05 D/y, or a cumulative increase in anisometropia ≥ 0.50 D over 10 years). Similar analyses were applied to aniso-AL.

Results: A total of 358/469 (76.3%) children had refractions at baseline and the 13-year visit. The mean (SD) amount of anisometropia increased from 0.24 D (0.22 D) at baseline to 0.49 D (0.46 D) at the 13-year visit. A total of 319/358 (89.1%) had slopes |b| < 0.05 D/y and 39 (10.9%) had slopes |b| ≥ 0.05 D/y, with only one negative slope. Similarly, 334/358 (93.3%) children had little change in aniso-AL over time. The correlation between changes in anisometropia and aniso-AL over 13 years was 0.39 (P < 0.001). The correlation between changes in anisometropia and myopia progression was significant (r = -0.36, P < 0.001). No correlation was found between baseline anisometropia and myopia progression (r = -0.02, P = 0.68).

Conclusions: Myopia and axial length progressed at a similar rate in both eyes for most children in COMET during the period of fast progression and eventual stabilization. These results may be more generalizable to school-aged myopic children with limited anisometropia at baseline. (ClinicalTrials.gov number, NCT00000113.).

Keywords: anisometropia; axial length; myopia.

Figure 1

Four examples with different rates of change for anisometropia. (A) Little anisometropia over time. (B) Little change in anisometropia over time. (C) Significant change in anisometropia over time. (D) Significant change in anisometropia over time. BL, baseline.

Figure 2

Histograms for rates of change in anisometropia and aniso-AL based on individual curve fitting.

Figure 3

The prevalence of clinically significant anisometropia (≥1.00 D) by visit.

Figure 4

Mean amount of anisometropia and aniso-AL over the years (±SE). The y-axis on the left side is for anisometropia and y-axis on the right side is for aniso-AL.

Figure 5

Mean amount of anisometropia (±SE) for more myopic progression (2.50 D or more progression in the fast progressing eye over 13 years, n = 163) and less myopic progression group (less than 2.50 D progression in the fast progressing eye, n = 195).

Figure 6

Anisometropia by ethnicity: Asian (n = 36 at BL), African American (n = 123 at BL), Hispanic (n = 68 at BL), Caucasian (n = 218 at BL), and mixed (n = 23 at BL). Only one subject was in the “other” ethnicity group (data not shown here).

Figure 7

Mean amount of aniso-AL (±SE) for more axial elongation (more than 1.275 mm axial elongation in the faster growing eye over 13 years, n = 179) and less axial elongation group (1.275 mm or less axial elongation in the faster growing eye, n = 179).

Figure 8

Aniso-AL by ethnicity: Asian (n = 36 at BL), African American (n = 123 at BL), Hispanic (n = 68 at BL), Caucasian (n = 218 at BL), and mixed (n = 23 at BL).