Purpose To investigate the effect of nicotine on choroidal thickness using optical coherence tomography (OCT).

Design Prospective, case–control study.

Methods Sixteen young, healthy subjects and 16 age and gender matched control cases were included in this study; 4 mg nicotine gum was given to the study group and placebo gum to the control group. All participants underwent OCT scanning with a high-speed and resolution spectral-domain OCT device (3D OCT 2000, Topcon, Japan) at baseline, and 1 h following nicotine or placebo administration. The measurements were taken in the morning (10:00–12:00 hours) to avoid diurnal fluctuation.

Results The median foveal choroidal thickness at baseline was 337.00 μm (IQR 84.50), which decreased to 311.00 μm (IQR 78.00) at 1 h following oral nicotine intake (p=0.001). The median choroidal thickness was also significantly decreased at five other extrafoveal points (p<0.05 for all). In the control group, the median baseline choroidal thickness at the fovea was 330.50 μm (IQR 104.25), and was 332.00 μm (IQR 103.75) at 1 h (p=0.271).

Conclusions Nicotine causes a significant decrease in choroidal thickness following oral intake. This acute decrease might be a result of reduced ocular blood flow due to the vasoconstrictive effect of nicotine.