Although the diagnostic value of optical coherence tomography angiography (OCT-A) compared with conventional OCT measurement in glaucoma remains inconclusive, many researchers and clinicians fall into the trap of assuming that newer is always better. However, researchers in Hong Kong took a closer look at both modalities, and found OCT-A has its limitations, leading them to believe conventional OCT remains a better option when viewing the macular in some cases.

The study, recently published in JAMA Ophthalmology, includes 115 patients with glaucoma and 35 healthy individuals. The researchers measured “retinal thickness and retinal vessel density over the 3x3mm2 macula using swept-source OCT (SS-OCT) and OCT-A, respectively. They found the inner macular vessel density was 4.3% smaller in eyes with glaucoma compared with healthy eyes. Inner macular vessel thickness was also smaller by 21.1μm, compared with healthy eyes.

When comparing the two measurements, they found that “at 90% specificity, the sensitivity of mean inner macular thicknesses for detection of glaucoma was greater than that of mean inner macular vessel densities,” the study said.

“OCT measurement of inner macular thickness shows a higher diagnostic performance to detect glaucoma and a stronger structure-function association than the currently used OCT-A measurement of inner macular vessel density,” the study authors conclude. “These findings may suggest that OCT-A of the macula has a limited role in the diagnostic evaluation of glaucoma.”

Wan KH, Lam AKN, Leung CK. Optical coherence tomography angiography compared with optical coherence tomography macular measurements for detection of glaucoma. JAMA Ophthalmol. May 31, 2018. [Epub ahead of print].