Evaluation of Accommodation and Pupillary Reaction in Children with Myopia Treated by Highly Diluted Atropine in the M.A.R.S. Trial

Abstract

Background: Myopia is a growing challenge in paediatric ophthalmology. Despite the benefits of novel therapeutic approaches, it is essential to assess their side effects. The aim of this study was to determine the impact of twelve months of local application of 0.02% and 0.04% atropine and placebo on the static and dynamic features of accommodation and pupil diameter, representing prominent side effects of myopia progression treatment.

Methods: This study involved 127 subjects aged 6-11 years who were randomized to the M.A.R.S. trial, a randomized, double-masked, placebo-controlled multicentre study investigating the efficacy, safety, and side effects of highly diluted atropine collyrium (0.02% and 0.04%) in slowing the progression of myopia. Photopic and mesopic light-adapted horizontal pupillary diameters (PD; mm) were measured. Static accommodation capability was assessed monocularly and binocularly as the amplitude of accommodation (AoA; dioptres) calculated as the inverted value of the measured near point of accommodation in meters. The dynamic properties of accommodation were represented by the near accommodation facility (NAF, ±1.25 D flipper; monocularly/binocularly; number of cycles in a 60-second interval).

Results: The effects of atropine on static PD were treatment-related (P<0.001) and dose-unrelated. Under photopic and mesopic light conditions, changes from baseline after twelve months of treatment were observed: in the 0.02% atropine group: from 3.48 ±1.23 to 4.65 ±1.52 (P<0.001); from 5.59 ±1.34 to 6.33 ±1.14 (P<0.001), respectively; in the 0.04% group: from 3.41±1.27 to 4.86±1.64 (P<0.001); and from 5.64±1.13 to 6.55±0.82 (P<0.001), respectively. The effects of the study medication on AoA were not treatment-related in the break point and were marginally treatment-related in the recovery point (P=0.049) in monocular tests. The results of the binocular tests were treatment-unrelated in the break point or at the recovery point. There were no statistically significant differences in NAF among the groups after the 12-month treatment period in monocular and binocular conditions.

Conclusions: Local 0.02% and 0.04% atropine treatment for twelve months resulted in treatment-related increases in photopic and mesopic PD, respectively. Accommodation capability, assessed by AoA, was diminished by atropine treatment only at extreme limits (due to enlarged NPA distances) but remained unchanged at standard near working distances (as indicated by unaltered NAF test results) according to the M.A.R.S. trial data.