To assess the effect of mask wear on corneal topography and tomography readings. Setting: Tertiary ophthalmic center. Design: Prospective, observational, comparative study.
Subjects underwent imaging with the Tomey® TMS-4a topographer and the OCULUS Pentacam® HR tomographer. Imaging was performed without a mask and then testing was repeated while wearing three different masks: Halyard Level 2, Halyard Level 3 and KN95. Measurements during mask wear were compared to measurements without a mask. Kruskal-Wallis ANOVA grouped test was used to compare mean differences without vs with mask wear on measurements. Chi-square test was used to compare frequency of differences between different masks and against-the-rule versus with-the-rule astigmatism. The frequencies of clinically significant changes in axis of astigmatism, magnitude of astigmatism and mean keratometry values were calculated.
52 eyes were included in the study with a mean age of 34.71. Mask wear did not show statistically significant differences in mean topography and tomography measurements compared to without mask wear for all parameters. However, the majority, 53% (83/156) had a >10 degrees and 41% (64/156) had >15 degrees change in axis of astigmatism on topography when wearing a mask compared to no mask wear.
Mask wear did not result in statistically significant mean changes in keratometry readings on topography and tomography. However, axis of astigmatism varied >10 degrees in the majority of patients. Axis determination should be interpreted with caution with respect to refractive surgery and/or toric intraocular lens planning in individuals whose measurements were obtained while wearing a mask.