Discussion
myopia, PD, myopic
CONSTRICTION, MYOPIA, RETINA, MYOPIA
This study found that pupil size and the constriction ratio could return to pre-atropine levels after cessation. A once-nightly dose of 0.01% atropine eyedrops induced the PD increase and decreased constriction ratio but did not influence the PLR. The condition of pupil metrics before atropine treatment and the changes of pupillary parameters during treatment had no significant effect on myopia progression.As a nonselective muscarinic antagonist agent, low-dose atropine for controlling myopia progression has aroused general interest, and its efficacy has been preliminarily recognized in recent years [Studies have reported that children in 0.01% and 0.02% atropine groups were photophobic in bright sunlight at the beginning of the treatment, but the symptom was not obvious in normal indoor lighting or when the sunlight was not intense outside [According to Yam’s report, after 4 months of 0.01% atropine eyedrops treatment, photopic PD increased by 0.26 ± 0.83 mm and mesopic PD increased by 0.18 ± 0.46 mm; after 8 months of treatment, photopic PD increased by 0.41 ± 0.80 mm and mesopic PD increased by 0.16 ± 0.46 mm [Most studies reported the psychophysical changes 1 year after the instillation of the drops. In a meta-analysis, 1-year randomized controlled trials showed both photopic (weighted mean difference, 0.35 mm; 95% CI = 0.02, 0.68) and mesopic PD (weighted mean difference, 0.51 mm; 95% CI = 0.31, 0.71) increased significantly in the 0.01% atropine group compared with control groups [Summary of design and pupillary parameters from RCTs case–control studies that include 0.01% atropineThe Atropine Treatment of Myopia trials (ATOM 2) phase 2 study assessed changes in pupil size in eyes treated with 0.01%, 0.1%, and 0.5% atropine after cessation [Some studies indicated that the change of PD after atropine treatment may contribute to myopic progression. Fu et al. reported that the AL of children with a smaller PD might increase rapidly while receiving atropine treatment, indicating that changes in PD may suggest the response to the effects of low-concentration atropine [Some mechanisms have been postulated to explain the association between myopia and pupil metrics. Pupil size could determine the amount of light entering the eyes, and larger pupils could allow more light to reach the peripheral retina, resulting in more peripheral defocus and thus affecting myopic progression [