Visual Field Artifacts From Face Mask Use

The coronavirus (COVID-19) pandemic has had a profound impact on how glaucoma care is delivered, necessitating reduced clinic flow, social distancing, and use of face coverings by patients and staff. This case highlights the need to be aware of improperly fitted face masks as a cause of artifact on standard automated perimetry (SAP).

A 32-year-old female underwent SAP with the 24-2 SITA Fast test of the Humphrey Field Analyzer wearing an ear-loop surgical face mask. At the end of testing, it was noted that the mask had ridden up the patient's face. Small amounts of condensate were noted on the perimeter lens.

SAP demonstrated good reliability indices but in both eyes, there was a marked reduction in sensitivity inferiorly. The glaucoma hemifield test was outside normal limits. It was ensured the upper border of the mask was well sealed with the loops secured around the ears and nasal strip of the mask pinched down. Visual fields were repeated and were found to be normal.

Poorly fitting face masks represent a new cause of visual field artifact which may mimic pathologic field defects. Without careful attention during testing, the cause of such artifacts may not be apparent, especially as reliability indices may be normal. Adjustments to the fit of face masks may help prevent fogging or mask slippage and increase test reliability.