Comparison between estimated and measured myopia progression in Hong Kong children without myopia control intervention

Abstract

Purpose: To compare myopia progression estimated by the Brien Holden Vision Institute (BHVI) Myopia Calculator with cycloplegic measures in Hong Kong children wearing single-vision distance spectacles over a 1- and 2-year period.

Methods: Baseline age, spherical equivalent refraction (SER) and ethnicity of control participants from previous longitudinal myopia studies were input into the BHVI Myopia Calculator to generate an estimate of the SER at 1 and 2 years. Differences between the measured and estimated SER (116 and 100 participants with 1- and 2-year subjective refraction data, respectively, and 111 and 95 participants with 1- and 2-year objective refraction, respectively) were analysed, and the measured SER compared with the 95% confidence interval (CI) of the estimated SER.

Results: In children aged 7-13 years, 36% progressed within the 95% CI of the Myopia Calculator's estimate, whereas 33% became less myopic than predicted (range 0.31 to 1.92 D less at 2 years) and 31% became more myopic than predicted (range 0.25 to 2.33 D more myopic at 2 years). The average difference between the estimated and measured subjective or objective SER at 1 and 2 years of follow-up was not clinically significant (<0.25 D).

Conclusions: On average, the BHVI Myopia Calculator estimated SER was in close agreement with measured cycloplegic SER after 1 and 2 years of follow-up (mean differences < 0.25 D). However, the measured myopia progression only fell within the 95% CI of the estimated SER for 32%-38% of children, suggesting that the BHVI 'without management' progression data should be interpreted with caution. The inclusion of additional data, modified to include axial elongation, from longitudinal studies of longer duration with larger sample sizes and a range of racial backgrounds may improve the Calculator's ability to predict future myopia progression for individual children.

Keywords: BHVI Myopia Calculator; myopia; myopia estimate; paediatric myopia; progression.

FIGURE 1

Bland‐Altman plots of the mean differences (Brien Holden Vision Institute (BHVI) estimates minus measured SER) versus their means, and the lower, upper bound of 95% CI at (a) 1 and (b) 2 years by objective refraction, and (c) 1 and (d) 2 years by subjective refraction. The solid line represents the mean difference and the dashed lines represent the upper and lower limits of agreement. Each error bar represents the 95% CI for the mean difference and limits of agreement. The data points in different colours denote when the measured SER was within the 95% CI of the estimated SER (white), was greater than the upper bound of the 95% CI of the estimated SER (Calculator prediction underestimates progression) (black), and was less than the lower bound of the 95% CI of the estimated SER (Calculator prediction overestimates progression) (red). (CI, confidence interval; SER, spherical equivalent refraction)