Temporal impacts of diverse concentrations of pilocarpine ophthalmic solution on human accommodation.

Clinical relevance: Accommodation is crucial for clear near vision and is predominantly affected by presbyopia. The ability to modulate accommodative function with eye drops could offer a pharmacological approach to manage presbyopia.

Background: To investigate the effects of different concentrations of pilocarpine eye drops on ocular accommodation in young volunteers.

Methods: In this prospective study, healthy volunteers with mild or moderate myopia with corrected visual acuity of no less than 20/20 were recruited. Participants underwent four visits for baselining and administration of low (0.75%), medium (1.00%), and high (1.25%) concentrations of pilocarpine eye drops respectively. One eye of each participant was chosen and analysed. Ophthalmologic examinations included objective and subjective refraction, corrected distance visual acuity, intraocular pressure, and pupil size. Accommodation was assessed using the WAM-5500 binocular autorefractor. Accommodation facility and the defocus curve were measured.

Results: Volunteers (n = 24, mean age 23.7 ± 1.5 years) with a mean spherical equivalent of -2.91 ± 1.54 dioptres (D) were recruited. No serious adverse events occurred. All pilocarpine concentrations showed similar pupil constriction without significant intraocular pressure changes (p > 0.05). Pilocarpine induced greater objective refraction changes with higher concentrations (-1.12 ± 1.07D, -1.56 ± 1.38D, -1.68 ± 1.60D for low, medium, and high concentrations, respectively; p < 0.01). Subjective refraction showed a similar dose-response. Accommodative response decreased significantly at the 20 cm stimulus for medium and high concentrations (p < 0.05). Corrected distance visual acuity improved beyond -1.00D to + 0.50D defocus after all three pilocarpines. Accommodative facility improved more by 1.25% than 0.75% (p = 0.04).

Conclusions: Pilocarpine eye drops are effective in improving ocular accommodation, with higher concentrations leading to greater accommodative changes. Pilocarpine has potential for managing presbyopia.