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Face mask fogging distorts perimetry results

A new study has found that ill-fitted face masks can cause either visual field artifacts – which may be interpreted as glaucoma progression – or low test reliability in standard automated perimetry (SAP) tests.

Researchers at University of Health Science within the Kayseri City Training and Research Hospital in Turkey tested 127 patients (59 female, 68 male) with glaucoma.

While 101 patients (79.5%) wore surgical face masks, 26 patients (20.5%) wore cloth face masks.

Low SAP reliability appeared in 23 patients (18.1%), and inferior visual field defects were present in three patients (2.4%).

“The main effects of poorly-fitting face masks on SAP reliability were increased fixation losses and false-positive errors,” the researchers concluded.

Low SAP reliability was significantly higher in patients wearing cloth face masks (47.8%) than in those wearing surgical face masks (9.9%).

“The face mask-related fogging of eyeglasses before SAP is a strong predictor of fogging of the trial lenses-related low SAP reliability,” the researchers stated.

They found taping the face masks’ upper edges was an effective technique to prevent visual field artifacts and obtain good test reliability.

In patients with low test reliability and/or visual field changes, SAP was repeated after repositioning and taping patients’ face masks. In each case, the patients’ reliability parameters improved, and inferior visual field artifacts disappeared.

More reading:

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Why face masks cause dry eye, and what ECPs can do to help

Repurposing surgery fabric to address masking shortage