No Consensus on Best Uses of OCTA

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OCT angiography (OCTA) has the potential to transform glaucoma diagnosis and predict glaucoma­tous damage. However, the emerging technology is not ready for clinical practice in glaucoma, according to an Ophthalmic Technology Assessment (OTA) from the Academy.¹

“The current literature does not support the routine use of OCTA in the diagnosis of glaucoma at this time,” said Darrell WuDunn, MD, PhD, at the University of Flor­ida College of Medicine in Jacksonville and lead author of the OTA.

What the literature tells us. A search of peer-reviewed literature yielded 60 articles that met the predefined inclusion criteria of the OTA. Most studies focused on OCTA measures of the optic nerve head and superficial peripapillary microvasculature. Others considered OCTA measures of macular microvascu­lature and peripapillary deep-layer microvasculature dropout. Researchers also looked at the association of peripapillary vessel density and macular density with visual fields (VFs) and with structural OCT parameters.

Findings included the following:

• Most studies detected significant correlation between glaucoma severity and degree of vessel density loss.
• Several studies found moderate to strong correlations or associations between OCTA vessel density and VF defects.
• Many found moderate correlation between the peri­papillary OCTA parameters and structural OCT parame­ters, both overall and in sectors, in glaucomatous eyes.
• Peripapillary OCTA showed better ability than mac­ular OCTA to differentiate glaucomatous and normal eyes.
• The peripapillary choroidal network may be a sur­rogate marker for optic nerve head circulation, and abnormalities in the choroidal microvasculature may correlate with glaucomatous optic nerve damage. 

Validating the technology. “I was impressed with how well OCTA vessel density correlated with tradi­tional structural and functional measures,” said Dr. WuDunn, adding that this finding reassured him of the technology’s validity. Even so, there is no consensus on OCTA’s best applications, despite its potential utility.

One impediment to moving forward with OCTA is a lack of interpretive software, Dr. WuDunn said. “For example, not all devices provide a vessel density mea­surement for different sectors or retinal layers.” What’s more, he added, “most lack a normative database, which would enable clinicians to assess whether a mac­ular or peripapillary OCTA image is abnormal.”

Looking ahead. Once analysis software and norma­tive databases become available, Dr. WuDunn predicted that OCTA will have a role to play. “I anticipate that peripapillary OCTA will become most useful in distin­guishing glaucoma suspects from healthy persons, and macular OCTA will be most effective in monitoring severe glaucoma.”

—Miriam Karmel

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1 WuDunn D et al. Ophthalmology. Published online Feb. 22, 2021.

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Relevant financial disclosures: Dr. WuDunn—Allergan: S.

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