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OCT-A study shows faster loss of vessel density in POAG
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Eyes with primary open angle glaucoma undergo faster loss of macular vessel density than glaucoma-suspect or healthy eyes, as shown by OCT angiography measurements.
Study participants were recruited from the Diagnostic Innovations in Glaucoma Study (DIGS). Thirty-two eyes with glaucoma, 30 glaucoma suspects and 38 healthy eyes were included in the analysis.
At baseline, eyes with primary open-angle glaucoma (POAG) presented significantly worse visual fields and a sparser microvascular network. The rate of change in vessel density loss over 14 months was significantly faster in eyes with glaucoma than in glaucoma suspects and healthy eyes.
“The faster rate of vessel density loss in glaucoma eyes could reflect the existence of dysfunctional or senescent retinal ganglion cells that have lower metabolic demands,” the authors wrote.
Evaluation of OCT-A vessel density may help predict glaucoma progression, improve the ability to manage glaucoma and “our understanding of the pathophysiology of the disease,” they concluded. – by Michela Cimberle
Disclosure: The study was supported, in part, by National Institutes for Health/National Eye Institute grants. Shoji receives financial support from Alcon. Please see the study for the other authors’ financial disclosures.
Perspective
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Derek MacDonald, OD, FAAO
Elevated IOP is inarguably an important and, currently, the only readily modifiable risk factor for glaucoma onset and progression. That being said, half of patients with glaucoma present with statistically normal pressures, and the majority of patients with ocular hypertension do not develop the disease.
It has long been hypothesized that compromised ocular blood flow may be contributory; however, its clinical utility and reproducibility has proven elusive.
Enter OCT angiography, which noninvasively (albeit indirectly) assesses circulation in the optic nerve head, retinal nerve fiber layer and macular retinal ganglion cell (RGC) layer. Investigators have found impaired blood flow at these sites, typically in good agreement with both location and severity of and of similar diagnostic accuracy as glaucomatous structural damage and functional loss.
Shoji and colleagues have demonstrated that in glaucomatous eyes, macular vessel density is decreased at baseline in a “dose-response” relationship, decreases more rapidly over time and, perhaps most interestingly, decreases in advance of demonstrable RGC loss. This may represent the detection of RGC dysfunction preceding death and provide a window to rescue devitalized but still-viable cells.
OCT-A appears poised to join automated visual fields and objective imaging as an invaluable complement in the diagnosis and management of glaucomatous optic neuropathy.
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