Seasonal Variation in Myopia Control in The Bifocal Lenses in Nearsighted Kids (BLINK) Study

Abstract

Purpose : Studies have shown there is a slower rate of myopia progression in the summer compared to the winter. The purpose of this analysis is to determine if there is seasonal variation in myopia control.

Methods : In the BLINK Study, 294 children ages 7-11 years old with baseline spherical myopia between -0.75 D and -5.00 D and with <1.00 D astigmatism were randomly assigned to single vision (SV), +1.50 (medium) add, or +2.50 (high) add center-distance soft multifocal contact lenses. Participants had to attend all 6 follow-up visits within ±35 days of target visit date. Myopia progression was the change in non-cycloplegic spherical equivalent autorefraction between 2 6-month visits. Semi-annual myopia progression was calculated using the COMET Study formula: (myopia progression / number of days between two visits) x 182.5. The midpoint date between 2 visits defined seasons. Summer = April-September and winter = October-March. Myopia control was the difference in progression rate between SV and medium add and between SV and high add multifocal contact lens wearers. The 3-year average semi-annual myopia progression and myopia control rates were compared by season.

Results : 223 participants met the inclusion criteria for this analysis. There were no significant differences between included and excluded participants for age at baseline, % sex, and baseline myopia (all p>0.05). The average semi-annual myopia progression rate over 3 years was -0.11±0.22D in the summer (S) and -0.23±0.19D in the winter (W, p=0.002) for SV, -0.10 ± 0.24D (S) and -0.21 ± 0.22D (W, p=0.005) for medium add, and +0.01 ± 0.22D (S) and -0.20 ± 0.21D (W, p=<0.001) for high add. The figure shows the average semi-annual myopia control rate between SV and medium add was +0.01 ± 0.23D in summer (p=0.84) and +0.02 ± 0.20D in winter (p=0.50), and between SV and high add was +0.12±0.22D in summer (p=0.002) and +0.03±0.20D in winter (p=0.34).

Conclusions : As expected from previous studies, myopia progresses faster in the winter than summer for all three groups, but myopia control with a high add was only meaningful in the summer.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Figure. The myopia control rate (difference in average semi-annual progression rate between the multifocal groups and single vision (SV) control group), where positive myopia control means the progression is faster for the SV group than the multifocal (+1.50 [medium] or +2.50 [high] add) groups, by season.