Optical coherence tomography (OCT) has the capability to help evaluate a variety of disease states and biological structures previously unable to be seen. As such, it’s becoming more commonly seen both in literature and in clinics across the country. But some of the finer points of these machines are still unclear. For instance, tweaking the signal to the appropriate strength is still under investigation. Now, a Johns Hopkins–based research team is looking to clear up how signal strength and artifact on retinal nerve fiber layer (RNFL) impacts measurement reliability and understand whether glaucoma severity modifies this relationship.

To accomplish this, the team looked at 2,992 OCT images from glaucoma patients and glaucoma suspects, extracting the mean RNFL thickness and signal strength for each scan, and compared them with a manual analysis of artifacts. They found that for signal strength between 10 and 3, the impact of decreases in strength on OCT reliability is modest. However, anything below 3 had a significant impact on reliability. Additionally, for patients with severe glaucoma, even decreases in signal strength between 10 and 3 had a large impact on reliability compared with mild or moderate glaucoma patients.

Yohannan J, Cheng M, Da J, et al. Evidence based criteria for determining peripapillary OCT reliability. Ophthalmol. August 29, 2019. [Epub ahead of print].