Maximum atropine dose without clinical signs or symptoms.

Purpose: Atropine 1% has been used to slow the progression of myopia; however, it has not gained worldwide clinical acceptance because it results in clinically significant pupillary mydriasis and accommodative paralysis. Lower concentrations of atropine (0.5 to 0.01%) have been reported to be associated with fewer symptoms, while still controlling myopia. It is the purpose of this study to find the highest concentration of atropine that does not result in significant symptoms from pupillary dilation and accommodative paralysis.

Methods: A 3 × 3 phase I clinical trial paradigm was used in 12 subjects, to determine the maximum dosage of atropine which could be prescribed without creating symptoms or clinical signs of insufficient accommodation or excessive pupillary dilation. Accommodation was measured by pushouts and pupillary dilation by photography. Prior to this study, we established the following criteria for comfort: 5D or more of residual amplitude of accommodation, less than or equal to a 3 mm pupillary difference between the eyes, and a report of minimal symptoms of near vision blur or outside photophobia.

Results: Our results indicate that atropine 0.02% is the highest concentration that did not result in clinical symptoms and findings associated with higher dosages. Mean pupillary dilation was 3 mm, and mean accommodative amplitude was 8 diopters with this concentration. Further, reduction of the concentration of atropine from 0.02 to 0.01% did not seem to result in a decrease in clinical signs or symptoms associated with atropine.

Conclusions: Atropine 0.02% is the highest concentration that does not produce significant clinical symptoms from accommodation paresis or pupillary dilation. This would be an appropriate starting point in evaluating a low dosage of atropine to slow myopic progression.