Effect of Topical Pilocarpine on Choroidal Thickness in Healthy Subjects

This is a proof-of-concept study showing the possibility of pharmacological control for choroidal thickness using pilocarpine as an agent that causes 2 to 5% choroidal thinning in healthy eyes after the instillation.

The purpose of this article was to study the effect of instillation of 1% pilocarpine on choroidal thickness in healthy subjects.

Sixteen healthy individuals (seven males and nine females; mean ± standard deviation age, 25.8 ± 3.3 years) were included. All participants received optical coherence tomography to evaluate subfoveal choroidal thickness (SCT) and choroidal area on cross-sectional scan within 4-mm central area. Axial length was measured using optical biometry. Optical coherence tomography was performed before and after pilocarpine was instilled six times for a 75-minute period in one eye; the fellow eye was used as the control. Subfoveal choroidal thickness and choroidal area were measured by two masked graders in random fashion and averaged for analysis.

After instillation of 1% pilocarpine, percentage SCT change in study and control eye was -3.3 ± 3.8% and 0.4 ± 3.2%, respectively (P = .03). Percentage change choroidal area in study and control eye was -2.3 ± 2.5% and 0.8 ± 3.3%, respectively (P < .001). There was a correlation between percentage SCT change and axial length (r = -0.56, P < .001), as well as between percentage SCT change and baseline SCT (r = 0.72, P < .001).

Instillation of 1% pilocarpine causes a decrease of choroidal thickness, which is more substantial in eyes with short axial length and thick choroid.