Little effect of 0.01% atropine eye drops as used in myopia prevention on the pattern electroretinogram

Daily administration of 0.01% atropine eye drops is a promising approach for myopia control. The mechanism of action is believed to involve the dopaminergic system of the retina, triggering an increased release of dopamine. Previous studies in psychiatric condition such as major depression suggest that pattern electroretinogram (PERG) amplitudes are modulated by changes in retinal dopamine. It is thus plausible that atropine eye drops could have an effect on PERG amplitudes. The present study was designed to test this, assessing the difference in amplitude between contrast levels and the ratio of amplitudes between check sizes as primary endpoints.

We included 14 participants with no more than ± 2 diopters of ametropia and visual acuity of at least 1.0. One eye was chosen randomly in each participant for atropine application (14 days, one drop of 0.01% atropine solution once daily before bedtime). We recorded two sets of steady-state PERG recordings: one with different contrasts (25% and 98%) and one with different check sizes (0.8° and 17°). Near-point distance, near visual acuity, and pupil diameter were measured additionally.

The recordings to different contrasts did not show atropine-related changes of PERG amplitude. A small increase by 6% of the amplitude difference between contrast levels with atropine application was not significant (p = 0.08). Raw amplitudes in the check size condition increased with atropine by 17% (p < 0.01) and 10% (p < 0.03) for small and large checks, respectively, without a significant concomitant effect on the amplitude ratio. Pupil size was significantly affected (median increase 0.5 mm, p < 0.002). However, neither of the experimental conditions was associated with a significant correlation between pupil size and PERG effects.

The effects on PERG primary endpoints after the 14-day period of atropine administration were small, especially compared to effect sizes in major depression, and statistically insignificant. Effects on raw amplitude were inconsistent. The present results suggest that retinal processing as reflected by PERG does not sizably change following a treatment regimen with atropine that is typical for myopia control.