0.01% atropine eye drops slows myopia progression without interfering with exotropia: JAMA
Intermittent exotropia (IXT), characterized by an intermittent outward deviation of 1 or both eyes, is one of the most common types of strabismus, particularly in Asian countries. Exotropia and myopia are commonly coexistent. Myopia has been identified as a risk factor for concomitant exotropia. It is thought that myopia is associated with a decreased demand for accommodation and, hence, lower convergence and a predisposition for developing exotropia. On the other hand, IXT has been regarded as a risk factor for myopia onset and progression.
In patients with IXT, additional accommodative convergence is required to maintain binocular vision and ocular alignment, which might increase accommodative loads and, hence, myopia progression. Alternatively, it was speculated that increased convergence demand (via convergence accommodation/ convergence), rather than accommodation, contributes to the myopia development in IXT.
Increased attention and further investigation seem warranted in the management of myopia progression in children with IXT, prompting this evaluation of low-concentration atropine in children with IXT, as previous clinical trials of atropine for myopia control excluded children with strabismus. The current 2-year, placebo-controlled, randomized clinical trial included evaluation of the effects of 0.01% atropine eye drops on accommodative changes, exotropia conditions, and binocular vision in children with myopia and IXT (AMIXT) for which we report the 1-year primary results.
This placebo-controlled, double-masked, randomized clinical trial was conducted from December 2020 to September 2023. Children aged 6 to 12 years with basic-type IXT and myopia of −0.50 to −6.00 diopters (D) after cycloplegic refraction in both eyes were enrolled. Participants were randomly assigned in a 2:1 ratio to 0.01% atropine or placebo eye drops administered in both eyes once at night for 12 months. The primary outcome was change in cycloplegic spherical equivalent from baseline at 1 year. Secondary outcomes included change in axial length (AL), accommodative amplitude (AA), exotropia conditions, and binocular vision at 1 year.
Among 323 screened participants, 300 children were included in this study. A total of 200 children (66.7%) were in the atropine group, and 100 (33.3%) were in the placebo group. At 1 year, the 0.01% atropine group had slower spherical equivalent progression (P < .001) and AL elongation (P < .001) than the placebo group. The mean AA change was −3.06 D vs 0.12 D (P < .001) in the atropine and placebo groups, respectively. The 0.01% atropine group had a decrease in near magnitude of exodeviation whereas the placebo group had an increase (P = .03). In the atropine vs placebo group, respectively, the incidence of study drug-related photophobia was 6.0% (12 of 200 participants) vs 8.0% (8 of 100 participants; P = .51) and for blurred near vision was 6.0% (12 of 200 participants) vs 7.0% (7 of 100 participants) (P = .74).
The AMIXT randomized clinical trial evaluated the efficacy and safety of 0.01% atropine eye drops on myopia progression, exotropia conditions, binocular vision, monocular function, and safety parameters in individuals with myopia and IXT at 1 year. The 0.01% atropine group had slower myopia progression in both spherical equivalent measurement and AL among children with myopia and IXT. The 0.01% atropine group did not appear to have aggravated exotropia conditions, in terms of magnitude of exodeviation and exotropia control. The 0.01% atropine group did not appear to have worse binocular vision, supported by assessment of distant stereoacuity, near stereoacuity, NPC, AC/A, and FVA. In addition, the use of 0.01% atropine appeared safe with a mild decrease in AA and a mild increase in pupil size; stability of BCVA, near vision, IOP, and ECD; and low incidence of adverse events.
In summary, this placebo-controlled, double-masked, randomized clinical trial established that 0.01% atropine eye drops, although compromising AA to some extent, appeared effective and safe in slowing myopia progression without interfering with exotropia conditions or binocular vision in children with myopia and IXT.
Source: Zijin Wang, MD; Tianxi Li, MD; Xiaoxia Zuo, MD; JAMA Ophthalmol. doi:10.1001/jamaophthalmol.2024.2295 Published online July 3, 2024.
