How 0.05% atropine alters accommodation and vergence

Paper title: Response of accommodation and vergence systems to low dose atropine

Authors: Woodman-Pieterse EC (1), Hughes RPJ (1), Hopkins S (1), Cunningham AF (1), Niemand J (1), Romeo B (1), Westcott NL (1)

1. Centre for Vision and Eye Research, Queensland University of Technology, Brisbane, Queensland, Australia

Date: Published online September 5, 2025

Reference: Woodman-Pieterse EC, Hughes RPJ, Hopkins S, Cunningham AF, Niemand J, Romeo B, Westcott NL. Response of accommodation and vergence systems to low dose atropine. Ophthalmic Physiol Opt. 2025 Sep 5.

[Link to open access paper]

Atropine 0.05% is currently considered the concentration of choice for myopia control, balancing efficacy with an acceptable side effect profile. Although prior research has shown 0.01% atropine has minimal impact on accommodation and vergence, only one other study has assessed the effects of 0.05% atropine on binocular vision.1 As myopes are already predisposed to unstable binocular vision (e.g. higher and variable accommodative lags), understanding how myopia control treatments affect binocular vision is important. This study investigated the effect of 0.05% atropine eye drops on accommodation and vergence over 10 days, aiming to provide clinical insights about the impact on binocular vision associated with low-dose atropine use.

This was a double-masked, placebo-controlled trial in Australia involving 20 myopic young adults (mean age 22.3 years). Participants received either 0.05% atropine or placebo drops nightly for 9 days. Binocular vision testing was performed over a period of 10 days and included amplitude of accommodation (monocular and binocular), PRA/NRA, binocular accommodative facility, accommodative lag, near heterophoria, fusional vergences, and near point of convergence (NPC).

Key findings were as follows.

• Monocular and binocular accommodative amplitude decreased by 6.1 D in the atropine group by day-10, with no change in controls.
• PRA decreased by 3.7 D in the atropine group, while NRA remained unchanged.
• Binocular accommodative facility fell from 15 cpm to 0 cpm in the atropine group, as no participants were able to complete a single cycle due to an inability to clear −2.00 D lenses.
• Accommodative lag increased by 0.73 D with atropine use.
• Near heterophoria shifted by 5Δ towards esophoria after 10 days of atropine use.
• Negative fusional vergence (NFV) break reduced by 10Δ and recovery by 6.8Δ in the atropine group.
• There was no significant change in distance heterophoria, PFV, AC/A ratios, or the control group across 10 days.

While it is well established that low-dose atropine can reduce amplitude of accommodation, fewer studies have demonstrated that other components of the binocular vision system can also be affected.2 These insights are practically useful as the study’s design closely reflects current clinical use of 0.05% atropine administered nightly.

Ongoing use of 0.05% atropine led to a reduced ability to stimulate accommodation, an increase in accommodative lag, and an esophoric shift, accompanied by decreased divergence ability at near. Altogether, these findings suggest that low-dose atropine may place additional strain on the binocular vision system, particularly in children who engage in frequent near work, have shorter working distances, or present with esophoria at baseline. Ultimately, the main concern here is that this combination of increased near convergence and reduced divergence capacity may, over time, increase medial rectus muscle tone and lead to esotropia with longer-term atropine usage.3,4

The authors recommend that clinicians carefully evaluate binocular vision status before prescribing 0.05% atropine for myopia control and monitor for side effects 1-2 weeks after starting treatment. Routine assessment of near heterophoria and fusional reserves, in addition to accommodative function, is advised for all patients receiving 0.05% atropine.

A clear limitation of this study is the cohort consisted of young adults with a mean age of 22 years, which is at least a decade older than the age where atropine is typically prescribed. As accommodative amplitude and vergence responses differ significantly between children and adults, the results may not fully reflect treatment effects in younger patients. 

Although the study was placebo-controlled, complete masking may not have been maintained. As atropine causes noticeable changes on pupil size and accommodation, this could have affected participant behaviour on subjective tests such as PRA and BAF. 

The 10-day duration presents both a strength and a limitation: while it represents the longest investigation of binocular vision effects with atropine to date, it is possible that some of the observed changes could stabilise or evolve with longer-term treatment. However, in this study, all affected parameters continued to decline over the trial period.

Future studies should extend these findings by including paediatric participants over longer durations, and by investigating outcomes in children with reduced divergence reserves or near esophoria. These groups may warrant further investigation as they could be more vulnerable to binocular vision disruption.

Purpose: Few studies have comprehensively investigated the effect of low dose atropine on the binocular vision system beyond accommodative amplitude. This study examined the effect of 0.05% atropine eye drops on a range of accommodation and vergence parameters across a 10-day period.

Methods: Twenty myopic, adult participants (mean age [SD] 22.3 [1.0] years, mean spherical equivalent refraction [SD] -1.9 [1.0] D) were randomised to receive either atropine (0.05% atropine sulphate, n = 10) or control (0.9% sodium chloride, n = 10) eye drops for nightly use for nine consecutive nights. Accommodative posture, monocular and binocular accommodative amplitude (AA), positive and negative relative accommodation (PRA/NRA), binocular accommodative facility (BAF), distance and near heterophoria, positive and negative fusional vergences (PFV/NFV), near point of convergence (NPC) and gradient accommodative convergence to accommodation ratios (AC/A) were measured at baseline, day-3 and day-10.

Results: By day-10, accommodative lag had increased significantly and AA, PRA and BAF had all decreased significantly in the atropine group, while there were no significant changes in any of the control group measurements. Near heterophoria shifted significantly towards esophoria and the NFV break and recovery points were decreased significantly in the atropine group by day-10. Additionally, NPC reduced by a clinically significant amount (that bordered on statistical significance), with no changes found in the control group. There was no significant change in distance heterophoria, AC/A, NRA or PFV (all p > 0.05) at day-3 or day-10 in either treatment group.

Conclusions: Atropine (0.05%) use disrupted accommodation significantly over 10 days and increased convergence at near. While near heterophoria shifted towards esophoria, participants' ability to counteract this was also diminished by a reduction in NFV. This suggests that the near heterophoria and fusional reserves of children using 0.05% atropine for myopia control should be monitored closely.

[Link to open access paper]