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HomeNewsIll-Fiitted Face Masks Could Lead to Defects on Visual-Field Tests

Ill-Fiitted Face Masks Could Lead to Defects on Visual-Field Tests

NEW YORK (Reuters Health) – When patients wear unfitted face masks during a visual-field test, disease-progression artifacts may appear, particularly among glaucoma patients, according to a new study.

Using a surgical mask with a piece of medical tape on the bridge of the nose could reduce these mask-related effects and improve the accuracy of tests during the COVID-19 pandemic, researchers report in the British Journal of Ophthalmology.

“We have observed some unexpected cases with visual field deterioration in patients wearing face masks while performing the test,” said coauthor Dr. Francisco Munoz-Negrete of the University of Alcala in Madrid, Spain.

“If the progression is real, we need to increase glaucoma treatment,” he told Reuters Health by email. “It’s very important to avoid displacement of the mask or fogging the lenses that could produce false defects.”

Munoz-Negrete and colleagues reviewed more than 300 visual-field tests performed with a face mask and compared them with tests performed before the COVID-19 pandemic. In most cases, patients were previously considered stable and hadn’t had significant changes in intraocular pressure or the thickness of their retinal nerve fiber layer.

In cases of suspected pseudoprogression due to mask artifacts, the team then scheduled new appointments to repeat the visual field test to check if the suspected defects disappeared.

They used the same test conditions but changed out the patient’s mask for a fitted surgical mask and placed medical tape on the bridge of the nose. They placed the mask as low as possible on the nose and covered the entire top of the mask with tape to prevent fogging or movement of the mask.

After the rescheduled appointments, the research team found 18 eyes from 12 patients, or about 6%, with pseudoprogression due to masks. In all of them, the visual field index and mean defect count significantly improved after fitting the mask and using tape on the bridge of the nose. With the fitted masks, the 18 tests no longer showed significant differences from the pre-pandemic tests.

“A common problem is the face mask causes fog to build up on the lens placed in front of the eye during the visual field test,” said Dr. Andrew Tatham of Princess Alexandra Eye Pavilion in Edinburgh, Scotland. Dr. Tatham, who wasn’t involved with this study, has written about visual field artifacts that may appear with face mask use.

“Steaming of the lens could cause the patient to miss test points that they otherwise would have seen,” he told Reuters Health by email. “A poorly fitted face mask may also rise up to obscure part of the vision during testing.”

The Spanish research team also found that the interior field was most affected when a patient wore an unfitted mask, which showed up as a new blind spot or an extension of a previous defect. The central and paracentral areas were sometimes affected as well.

Some patients also described discomfort with wearing a mask and felt shortness of breath while performing the visual field test, which could lead to fatigue and false defects, particularly in older patients, the authors write.

As the pandemic continues, eye specialists should consider using paper surgical adhesive tape and surgical masks to garner the best results on visual field tests, the authors write. The hypoallergenic, latex-free tape adheres to skin and leaves minimal residue, which is a good option for patients with sensitive skin, they add. None of the patients in the study experienced a medical adhesive-related skin injury after removing the tape.

“Many people find the test difficult to perform . . . and wearing face masks can make visual field testing more challenging,” Dr. Tatham said. “It is important that clinicians are aware that poorly fitted face masks can cause apparent defects on visual field testing, which unless recognized, may lead to patients being falsely assumed to be progressing.”

SOURCE: British Journal of Ophthalmology, online February 17, 2021.

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