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ABSTRACT
Glaucoma is the leading cause of irreversible vision loss and comprises a group of chronic optic neuropathies characterized by progressive retinal ganglion cell (RGC) loss. Various etiologies, including impaired blood supply to the optic nerve, have been implicated for glaucoma pathogenesis. Optical coherence tomography angiography (OCTA) is a non-invasive imaging modality for visualizing the ophthalmic microvasculature. Using blood flow as an intrinsic contrast agent, it distinguishes blood vessels from the surrounding tissue. Vessel density (VD) is mainly used as a metric for quantifying the ophthalmic microvasculature. The key anatomic regions for OCTA in glaucoma are the optic nerve head area including the peripapillary region, and the macular region. Specifically, VD of the superficial peripapillary and superficial macular microvasculature is reduced in glaucoma patients compared to unaffected subjects, and VD correlates with functional deficits measured by visual field (VF). This renders OCTA similar in diagnostic capabilities compared to structural retinal nerve fiber layer (RNFL) thickness measurements, especially in early glaucoma. Furthermore, in cases where RNFL thickness measurements are limited due to artifact or floor effect, OCTA technology can be used to evaluate and monitor glaucoma, such as in eyes with high myopia and eyes with advanced glaucoma. However, the clinical utility of OCTA in glaucoma management is limited due to the prevalence of imaging artifacts. Overall, OCTA can play a complementary role in structural OCT imaging and VF testing to aid in the diagnosis and monitoring of glaucoma.
LIST OF ABBREVIATIONS
| AI | = | artificial intelligence |
| AUROC | = | area under receiver operator characteristic curve |
| FAZ | = | foveal avascular zone |
| FDA | = | food and drug administration |
| FI | = | flow index |
| GCC | = | ganglion cell complex |
| GCIPL | = | ganglion cell-inner plexiform layer |
| ILM | = | inner limiting membrane |
| INL | = | inner nuclear layer |
| IOP | = | intraocular pressure |
| IPL | = | inner plexiform layer |
| LC | = | lamina cribrosa |
| MD | = | mean deviation |
| MvD | = | microvasculature dropout |
| NFLP | = | nerve fiber layer plexus |
| NTG | = | normal tension glaucoma |
| OCT | = | optical coherence tomography |
| OCTA | = | optical coherence tomography angiography |
| ONH | = | optic nerve head |
| ONL | = | outer nuclear layer |
| OPL | = | outer plexiform layer |
| PACG | = | primary angle closure glaucoma |
| POAG | = | primary open angle glaucoma |
| PPG | = | preperimetric glaucoma |
| RGC | = | retinal ganglion cell |
| RNFL | = | retinal nerve fiber layer |
| RPC | = | radial peripapillary capillaries |
| RPE | = | retinal pigment epithelium |
| SSADA | = | Split-Spectrum Amplitude Decorrelation Angiography |
| SVC | = | superficial vascular complex |
| VD | = | vessel density |
| VF | = | visual field |
| XFG | = | exfoliation glaucoma |
DISCLOSURE STATEMENT
LQS is a consultant for FireCyte Therapeutics, Inc.
FINANCIAL SUPPORT
MB was supported by The Glaucoma Foundation.