Influence of Different Concentrations of Carbachol Drops on the Outcome of Presbyopia Treatment – A Randomized Study

Purpose: To evaluate and compare in a masked fashion the influence of using two different concentrations of carbachol drops on the outcome of presbyopia treatment. Methods: A prospective, double-masked, randomized study. 57 emmetropic and presbyopic subjects aged between 44 and 60 years with an uncorrected distance visual acuity of at least 20/20 in both eyes without additional ocular pathology were eligible for inclusion. Subjects were divided into 2 groups. Group 1 (n=32 eyes) received single dose of 2.25% carbachol plus 0.2% brimonidine eye drops. Group 2 (n=25) received single dose of 3% carbachol plus 0.2% brimonidine eye drops. The subjects’ pupil size and both near and distance visual acuities were evaluated before and after treatment at 1, 2, 4, 8 and 12 hr, by a masked examiner at the same room illumination. Results: Statistically significant improvement in mean near visual acuity (NVA) was achieved in all subjects who received both concentrations of carbachol plus brimonidine drops (P < 0.0001). Significant and sustained improvement in mean NVA was reported in higher concentrations of carbachol drops than in lower concentrations (P < 0.0001). No serious adverse ocular effects were observed in any of the subjects of both groups. Conclusion: Based on the data, higher concentration of carbachol was found to be safe and provided greater efficacy in improving near visual acuity than lower concentration with prolonged duration of action.