Evaluation of the effect of n95 face mask used by healthcare professionals on choroidal thickness

Purpose: We aimed to show the changes in choroidal thickness (CT) with spectral domain optical coherence tomography (SD-OCT) after prolonged use of N95 mask. Method: The healthcare workers who use the N95 face-mask, between 30-50 years of age who have best corrected visual acuity (BCVA) >= 10/10, spherical or cylindrical refraction errors less than 2 diopters, with normal intra ocular pressure (IOP), axial length (AL) between 22-24 mm included in the study. The choroid was imaged with enhanced depth imaging (EDI) techniques using SD-OCT. CT was measured, subfoveal, at 1000 um nasal and temporal of the center of the fovea. Measurements were first made after wearing the N95 mask for at least 2 h without removing it and repeated 15 min after removing. Results: After 2 h of the N95 mask using without removal, the mean subfoveal CT was 293.56 +/- 76.12(min:185, max:479), the mean temporal CT was 253.81 +/- 63.48(min:172, max:384), the mean nasal CT was 239.18 +/- 53.92(min:139, max:356). Fifteen minutes after removal of the N95 mask, the mean subfoveal CT was 250.56 +/- 52.48(min:172, max:397), the mean temporal was 218.40 +/- 53.58(min:129, max:354), the mean nasal CT was 210.67 +/- 53.31(min:132, max:366). The differences in subfoveal, temporal and nasal CT between 2 h of N95 mask use and 15 min after removal of the mask were statistically significant (p < 0.05 for each). Conclusion: Hypercapnia due to prolonged use of the N95 mask may cause choroidal hemodynamic changes and transient increased choroidal thickness.