Intraocular Pressure Measurement Variability Associated With Face Mask Use.

Précis: Masks have a multi-factorial impact on intraocular pressure measured with the Goldmann tonometer, reaching clinical significance in one-third of patients. Before making clinical decisions, repeated measurements without a mask or other tonometers should be considered.

Purpose

To investigate the impact of wearing face masks on intraocular pressure (IOP), the only manageable factor today in glaucoma, a blinding disease. Given the recurrent global outbreaks of respiratory infections (e.g., COVID-19, RSV, and measles), mask use remains a crucial measure to reduce transmission.

Methods

A prospective, randomized, controlled, and blinded clinical study. Adult patients without corneal pathologies or hypotony were recruited in the glaucoma clinic. Each patient underwent IOP measurements using the Goldmann applanation tonometer under three conditions: with a surgical mask, KN95 mask and without a mask as the control.

Results

47 patients (94 eyes) with various types of glaucoma, were enrolled. Past ocular history included an average of IOP-lowering medications of 1.7±1.5 (range 0 to 5), 25.5% had prior laser treatment for IOP control, and 19.1% had previously undergone glaucoma surgery. The mean difference in IOP readings between the masks ranged from 0 to 7.5 mm Hg with no statistical significance, P=0.116. No significant differences were found based on gender (P=0.560), laterality (P=0.384), number of IOP-lowering medications (P=0.730), history of previous glaucoma laser treatment (P=0.456), or surgery (P=0.425). Sixteen patients (34.0%) exhibited an IOP difference of 3 mm Hg or more between the conditions, although not statistically significant (P=0.546).

Conclusion

Masks exert inconsistent effects on IOP measurements. In approximately one-third of patients the differences reached clinical significance, although not statistically significant. These variations are presumably influenced by multiple factors, such as mask fit to facial structure, positioning, and alterations in breathing patterns while wearing masks.