PURPOSE: We aimed to examine the changes in choroidal stroma and vascular system due to long-term use of N95 mask in healthcare workers. METHOD: The healthcare workers included in the study were between the ages of 18-50, with best corrected visual acuity (BCVA) 10/10, spherical and cylindrical refractive errors less than 3 diopters, intraocular pressures (IOP) within normal limits, and axial lengths (AL) less than 25 mm. The choroid was imaged with enhanced depth imaging (EDI) techniques using SD-OCT. The choroidal vascularity index (CVI), total choroidal area (TA), luminal area (LA), and stromal area (SA) were measured in the subfoveal 2 mm area. Measurements were first made after wearing the N95 mask for at least 2 hours without removing it and repeated 1hour after removing, while doing office working. RESULTS: The study included 62 eyes from 62 participants (32 women [%51.61]; 30 men [%48.39]). The mean age of patients was 33.81+/- 8.88 years (20-50 years). The differences in subfoveal TA, LA, SA between 2 hours of N95 mask use and 1 hour after removal of the mask were statistically significant (p<0.05 for each). However, the difference in CVI between the mask use and removal of the mask was not statically significant (p=0.537) CONCLUSION: Due to CO2 retention and hemodynamic changes, choroidal vascular flow, the choroidal vascular area, and the choroidal stromal area may be affected by prolonged use of masks.