Objectively Measured Digital Near Work Behaviour During MiSight Contact Lens Wear

Abstract

Purpose : While MiSight contact lenses (CL) provide an effective myopia control treatment by introducing peripheral myopic defocus, their impact upon real-world near work behaviours, a significant myopia risk factor, remains unknown. With the growing use of digital devices at near distances, this study aimed to examine aspects of the digital near work behaviour during short-term MiSight CL wear in healthy myopes.

Methods : A custom-made head-worn device featuring pupil and gaze tracking technology along with real-time fixation depth mapping at 30 Hz was used on 17 low myopic (-2.68 ± 1.12 D) young adults aged 22 ± 2 years, to measure the changes in focusing demand (FD) and pupil size (PS) during a smartphone near task. The near task involved reading a novel extract (high contrast text, height of upper-case vertical letters 3 mm) continuously for 3 mins at preferred reading posture in photopic indoor lighting (200 lux), under the light mode (black text on a white background) and dark mode (white text on a black background) of the smartphone. Myopia was optimally corrected using a dual focus MiSight and a single vision ProClear CL as a control condition, on separate days in random order. Changes in FD and PS with CL type, display polarity, and time were examined with repeated measures ANOVA. Correlation between changes in FD and PS changes was tested with ANCOVA.

Results : The mean FD was 2.9 ± 0.1 D and did not change significantly with CL type (p=0.94) but increased over time by 0.12 ± 0.05 D after 3 mins reading from baseline (p=0.03). FD was significantly greater under dark mode versus light mode viewing by 0.14 ± 0.05 D (p=0.02). The mean PS was 3.0 ± 0.1 mm and did not change significantly with CL type (p=0.71) but decreased over time by -0.19 ± 0.05 mm after 3 mins reading from baseline (p<0.001). PS also decreased under light mode versus dark mode viewing by -0.18 ± 0.02 mm (p<0.001). The observed changes in FD were not associated with changes in the PS (p=0.53).

Conclusions : MiSight CL wear did not change the focusing demand during a brief smartphone reading, suggesting that the additional peripheral plus power was not utilized, and the induced myopic blur was likely maintained during reading. Reading under dark mode viewing increased the focusing demand, independent of the observed increase in pupil size, suggesting that factors other than depth of focus, such as screen reflection, may have played a role.

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