OCT in Glaucoma: Artifacts and Anomalies

With widespread use of optical coherence tomography (OCT) in glaucoma, clinicians need to be prepared for the potential of misleading artifacts and anomalies, said Yao Liu, MD, at Glaucoma Subspecialty Day.

Artifacts. These affect as many as 1 in 3 OCT scans, and they occur with all OCT systems. Some are technical in nature. “The number-one problem is poor scan centration,” she said. Other technical problems include motion and blink artifacts and software-related segmentation errors. Artifacts also may be related to the presence of moderate to severe cataract.

Anomalies. These are characteristics that may cause deviations from normative values. “Most anomalies are related to myopia” and high axial length, Dr. Liu said. And certain retinal conditions also may affect “not only 1 scan but also a series of scans over time.”

Overall, “It’s important to be critical when interpreting test results,” she said. In particular, clinicians need to avoid mistakenly treating “red disease” rather than actual glaucoma. Areas flagged in red on the OCT report represent thin RNFL measurements relative to the normative database, but they do not always represent glaucoma.

Several technical advances in development—including automated scan circle placement, improved segmentation algorithms, and compensation for retinal vascular density—may help ameliorate these problems, Dr. Liu noted.—Jean Shaw

Dr. Liu has no financial disclosures.