Effect of Mask Mandates on the Intraocular Pressure Measured via Goldmann Applanation Tonometry

Purpose: The corona virus disease-19 (COVID-19) pandemic has resulted in mandatory masking of patients and physicians during outpatient visits. This study evaluated the changes in intraocular pressure (IOP) according to mask use.Methods: This prospective study enrolled 30 healthy volunteers (60 eyes). IOP was measured via Goldmann applanation tonometry (GAT) for the subjects wearing one of four commonly used masks: dental, bi-folding Korean Filter (KF)94, tri-folding KF94, and dust masks. Subjects with IOP measurement errors of more than 5 mmHg were rechecked with another GAT type.Results: The mean IOP measured via GAT before mask wearing was 13.7 ± 1.7 mmHg. It was 13.5 ± 2.1, 14.0 ± 2.3, 14.3 ± 2.5, and 13.8 ± 1.6 mmHg with the dental, bi-folding KF94, tri-folding KF94, and dust masks, respectively. There were no significant differences in IOP according to mask type (p = 0.635). IOP errors above 5 mmHg were detected in three subjects who had contact between the GAT feeler arm and tri-folding KF94 mask during IOP measurement.Conclusions: The IOP as measured via GAT is artificially elevated by mechanical interference from the tri-fold KF94 mask. To minimize such mask-induced artifacts in GAT measurements, compress the patient’s mask or change the mask type to prevent any contact during measurement.