Pupil Size and Myopia Progression in the Bifocal Lenses In Nearsighted Kids (BLINK) Study

Abstract

Purpose : The BLINK Study was a 3-year clinical trial that evaluated center-distance multifocal contact lenses (MFCLs) for myopia control and found reduced myopia progression and eye growth with +2.50 add MFCLs compared to single vision contact lenses (SVCLs). This analysis explores whether pupil size influenced the magnitude of the treatment effect.

Methods : Myopic children (n = 294; 7-11 years old; 60% female) were enrolled (mean ± SD age = 10.3 ± 1.2 years) and randomly assigned to one of 3 groups: SVCL, +1.50 MFCL, or +2.50 MFCL. Children had -0.75 D to -5.00 D of myopia (most hyperopic meridian) and <1.00 D astigmatism at enrollment (mean ± SD spherical equivalent = -2.39 ± 1.00 D). Pupil size (right eye) was measured at baseline and each annual visit under photopic (~500 lux) and mesopic (~2 lux) lighting with a NeurOptics VIP-200 pupillometer. Models of the 3-year change (right eye) in cycloplegic spherical equivalent refractive error (RE; measured by autorefraction) and axial length (AL; measured by optical biometry) were fit with mean photopic or mesopic pupil size, either baseline RE or AL, treatment group, sex, study site, and age. Interactions between pupil size and treatment group were evaluated as the main outcome of interest.

Results : Mean (± SD) photopic and mesopic pupil size were 5.0 ± 0.6 mm (range: 3.3 to 6.9 mm) and 6.4 ± 0.7 mm (range: 4.5 to 8.4 mm), respectively, with no difference between treatment groups (photopic p = 0.60; mesopic p = 0.62). When modelling the 3-year change in spherical equivalent RE, neither photopic (p = 0.67; 95% CI: -0.40 to +0.25 D/mm pupil size) nor mesopic pupil size (p = 0.47; 95% CI: -0.41 to +0.19 D/mm pupil size) modified the slowing of myopia progression found in the +2.50 MFCL group (i.e., no treatment by pupil size interaction). With respect to change in AL, neither photopic (p = 0.92; 95% CI: -0.13 to 0.15 mm AL change/mm pupil size) nor mesopic pupil size (p = 0.37; 95% CI: -0.07 to 0.19 mm AL change/mm pupil size) modified the slowing of AL found in the +2.50 MFCL group.

Conclusions : Larger pupils have been hypothesized to have a greater treatment effect with center-distance MFCLs by exposing the retina to additional plus power. Pupil size did not modify the size of the treatment effect when children wore MFCLs in the BLINK Study. These results do not support using pupil size as a criterion when evaluating which myopic children to fit with this MFCL.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.