Effect of Topical Pilocarpine on Choroidal Thickness in Healthy Subjects.

SIGNIFICANCE: 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.

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

METHODS

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.

RESULTS

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).

CONCLUSIONS

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