Optical Coherence Tomography Angiography Scans Unmarred by Face Mask Wear

Face masks are no barrier to reliable and effective optical coherence tomography angiography (OCT-A) scans, according to a study published in the Journal of Glaucoma. While some reports have documented unreliable visual field (VF) tests and artifacts because of fogging and improper face mask fit, researchers say OCT-A scans have no significant increase in artifacts when patients wear masks, nor do masks cause any clinically significant effect on optic nerve head (ONH) or macular vessel density measurements using the technology.

To verify if mask wear interferes with OCT-A scans, researchers set out to assess differences in area of artifacts observed in OCT-A scans with and without face mask wear. The study assessed 64 eyes of 39 patients. Participants included 4 individuals with ocular hypertension, 8 individuals with suspected glaucoma, 17 individuals with glaucoma, and 10 healthy individuals. Researchers obtained high density optic nerve head (ONH) and macula OCT-A scans on patients with and without surgical masks. Quantitative evaluation was performed by 2 trained graders looking toward motion, decentration, defocus, shadow, segmentation failure, blink, and Z-offset to evaluate differences of vessel density. 

For the most part, the researchers report that when artifacts were identified in the masked scans, they were also found in the unmasked scans for the same eye. For ONH scans, 62 of 64 eyes had artifacts before and after face masks were applied. For macula scans, researchers saw the same result in 61 of 64 eyes. Fewer that 15 eyes had artifacts only when a mask was worn.

While results show trends of increasing motion artifact area for ONH scans (P =.08) and defocus artifact area for macular scans (P =.08) were found with face mask wear, there were no significant differences in the mean percentage area of any artifacts (P >.05 for all). 

“The estimated mean difference in vessel density in images acquired without and with face masks was not significant for any type of artifact,” researchers note.

Study limitations include a relatively small sample size, unique study methodologies, and the use of only one OCT-A device, thereby limiting extrapolation of results using other OCT-A devices. 

These findings point up the need for clinicians and researchers to identify and minimize other main causes of artifacts, such as operator-related error, patient-related factors, and software errors in order to avoid clinical misinterpretations and inappropriate investigations, and to accurately interpret vessel density measurements.

Reference

El-Nimri N, Micheletti E, Mohammadzadeh V, et al. OCT angiography face mask-associated artifacts during the COVID-19 pandemic. J Glaucoma, Publish online March 23, 2022. doi:10.1097/IJG.0000000000002019