Accommodative behaviour and retinal defocus of children during prolonged viewing of electronic devices while wearing dual-focus myopia control soft contact lenses.

Abstract

Purpose: Chronic hyperopic defocus from inadequate accommodation during near tasks may be associated with axial eye growth. This study examined accommodative behaviour and retinal defocus in myopic and emmetropic children after 1 h of continuous electronic device use.

Methods: Thirty-four children (17 per group, aged 7-17) participated, including myopes wearing dual-focus (DF) myopia control contact lenses (MiSight 1-day) and uncorrected emmetropes. In phase one, on-axis aberrometry data were collected at distances from 4.00 to 0.20 m, corresponding to target vergences from -0.25 to -5.00 D. In phase two, measurements were taken every 10 mins, as children watched a movie at 0.20 m for 60 min. Local refractive state measures were calculated from aberrometry measures and pooled within pupil areas corresponding to DF lens central and treatment zones. Retinal defocus was calculated by subtracting target vergence from the measured refractive state. Linear mixed-effects models analysed group, target vergence and time effects on defocus, adjusting for pupil diameter.

Results: Myopes with DF lenses showed greater hyperopic defocus (+0.58 D, p = 0.001) than uncorrected emmetropes during on-axis viewing. Hyperopic defocus increased significantly over time in both groups with near viewing (p < 0.001). Myopic defocus induced by DF lenses was still present but decreased following 50 and 60 min of near viewing (p = 0.05 and p = 0.007, respectively).

Conclusions: Periods of sustained near viewing of up to 1 h increased hyperopic defocus in both groups. However, DF contact lenses still introduced myopic defocus in myopic subjects throughout this time, supporting their potential to slow axial eye growth during periods of sustained near viewing. Further work will be helpful to understand how the sustained near viewing model and associated results of the current work relate to the real-world environment, which may include potential breaks and/or longer total near viewing durations.