A proof-of-concept study from a team of Russian researchers reports pilocarpine may be able to reduce choroidal thickness by between 2% and 5% in healthy eyes.

The research, published in Optometry and Vision Science, included 16 patients who were about 26 years old and were administered 1% pilocarpine. All participants underwent OCT imaging to evaluate subfoveal choroidal thickness (SCT) and the choroidal area as seen on cross-sectional scans within a 4mm central area. The investigators measured axial length with optical biometry and performed OCT before and after pilocarpine instillation, which was done six times for a 75-minute period in one eye. The fellow eye was used as the control. Two masked graders randomly measured SCT and the choroidal area.

After the instillation of 1% pilocarpine, the SCT change in the study eye and the control eye was -3.3±3.8% and 0.4±3.2%, respectively. Additionally, the change of the choroidal area in the study and the control eye was -2.3±2.5% and 0.8±3.3%, respectively.

The researchers noted a correlation between the percentage SCT change and axial length as well as between the percentage SCT change and baseline SCT.

A decrease in choroidal thickness appeared to be more substantial in eyes with shorter axial lengths and thicker choroids.