Nicotine appears to cause choroidal thinning

This prospective, case-control study found that nicotine causes a significant decrease in choroidal thickness following oral intake, possibly due to its vascoconstrictive effect.

While there is still debate about the exact relationship between choroidal blood flow and choroidal thickness, this study demonstrates a direct correlation between oral nicotine gum use and choroidal thinning.

Subjects included 16 young, healthy participants who were given 4 mg nicotine gum and 16 age- and gender-matched controls given placebo gum. All participants underwent OCT scanning with a high-speed and high-resolution spectral-domain OCT (3D OCT 2000, Topcon) at baseline and one hour following nicotine or placebo administration. The measurements were taken in the morning between 10 a.m. and 12 p.m. to avoid diurnal fluctuation.

Within one hour of nicotine intake there was appreciable choroidal thinning at the fovea from 337 µm to 311 µm. The median choroidal thickness was also significantly decreased at five other extrafoveal points (P < 0.05 for all). In the control group, the median choroidal thickness at the fovea was 330.50 μm at baseline and 332.00 μm at one hour.

The authors note the study’s small size and that they were unable to quantify blood levels of nicotine at the time of choroidal measurements.  

To the best of their knowledge, this is the first study to investigate the isolated effects of nicotine on choroidal thickness. Given the growing evidence in the literature on the relationship between choroidal thickness and choroidal blood flow, these findings may be of clinical importance.