Macular vascular microcirculation metrics can help delineate between stages of glaucoma, according to newly published research. However, visualizing those changes would have been nearly impossible before the development of OCT angiography (OCT-A). Now, with the technology starting to become more readily available, researchers have a new way to detect and track disease severity in glaucomatous eyes.

The researchers from the University of Washington looked into 20 normal eyes and 58 with primary open-angle glaucoma (POAG) and compared their macular OCT-A images with visual field central mean sensitivity. They measured the disease’s severity using four different staging scales (the Hodapp-Parrish-Anderson scale, the glaucoma severity staging system, the ICD-10 glaucoma staging definitions and visual fields mean deviation). They then measured macular vascular microcirculation by calculating the overall blood flux index (BFI) and vessel area density (VAD) over the entire 6mm×6mm area. 

They found that the glaucoma patients’ eyes had significantly lower ganglion cell-inner plexiform layer BFI and VAD than the normal eyes. Also, the BFI and VAD measurements were significantly higher in mild POAG cases than severe. Although they had similar results with all four classification systems, the glaucoma severity staging system had the highest correlation with macular vascular microcirculation changes as visualized with OCT-A, and the visual fields mean sensitivity had highest correlation with macular vascular microcirculation metrics.