The rate of myopia progression in children who become highly myopic

Abstract

Purpose: A retrospective study investigating whether those that become highly myopic have faster rates of myopia progression from ages 7 to 15 years.

Methods: One hundred and twelve eyes, 59 children, aged 7 to 15 & spherical refractive error (SE) ≥-6.00 D recruited to the ZOC-BHVI High Myopia Study were studied. Three years of their historical myopic changes were compared to that of 260 eyes of 156 children with SE from -0.50 to -3.75 D (2 yr prospective study). All wore standard spectacles. The low myopia group (LMG) underwent cycloplegic refraction & 93% of the high myopia group (HMG) did so at the 3 year visit. Refractive history of the HMG & parental myopia information from both groups were collected. Myopic increase per year per eye was analysed with respect to age at the start of the year. Equations were derived for rates of refractive error progression. Linear mixed models with subject intercepts as random effects were used to test for significant (p<0.05) associations with age, parental myopia, gender, baseline sphere.

Results: Fig. 1 shows myopic progression vs age for HMG & LMG. Mean ages at baseline: 10.4 ± 1.7 yrs (LMG) & 11.6 ± 2.6 yrs (beginning of historical record for HMG). Mean SE at baseline: LMG was -2.00 ± 0.80D (-0.37 to -3.8D); HMG was -5.00 ± 1.90D (-1.00 to -12.00D). Mean annual progression in SE for LMG: -1.14 ± 0.43D (age 7), -0.76 ± 0.36 D (age 10), -0.67 ± 0.20D (age 13) and -0.66 ± 0.16D (age 15). Mean annual progression in SE for HMG: -1.65 ± 1.05D (age 7), -1.02 ± 0.58D (age 10), -1.12 ± 0.69D (age 13) and -0.75 ± 0.47D (age 15). A significantly greater rate of progression was seen in the HMG vs LMG (p <0.01). Higher levels of myopia were associated with earlier onset & greater baseline amounts (both P<0.01). Parental myopia & gender were not associated with rates of change for either group. At 8 & 10 to 13 years, rate of myopia progression was significantly greater (p <0.5) for HMG. At 14 & 15 years, rates of change in myopia were found to be not different.

Conclusions: Children with high myopia with greater risk of and eventual vision impairment have consistently greater rates of myopic progression across the ages studied, developed myopia earlier and with initially higher levels. Parental myopia was not found to be a risk factor for higher rates of progression. These findings may help identify those at risk of developing high myopia and who would especially benefit from myopia control.

Keywords: 605 myopia • 677 refractive error development • 461 clinical (human) or epidemiologic studies: natural history