Optical Coherence Tomography Angiography in Detecting Subclinical Changes in Glaucoma Suspects: A Scoping Review.

Optical coherence tomography angiography (OCTA) offers a promising approach for detecting subclinical microvascular changes in glaucoma suspects before structural or functional damage becomes apparent. This scoping review synthesizes evidence from 11 studies (2014-2025) to evaluate OCTA's effectiveness in identifying early glaucomatous alterations. Findings consistently demonstrate reduced vessel density (VD) in glaucoma suspects compared to healthy controls, with whole-image VD averaging 51.3% versus 55.5% (P<0.001), respectively. OCTA-derived parameters, particularly peripapillary and macular VD, showed diagnostic accuracy (area under the receiver-operating characteristic curve (AUROC): 0.70-0.84) comparable to structural OCT metrics like retinal nerve fiber layer thickness. Notably, microvascular asymmetry and deep-layer capillary dropout emerged as early markers, often preceding visual field defects. Longitudinal data revealed faster VD decline in preperimetric glaucoma (-2.23%/year) than in healthy eyes (0.29%/year), highlighting OCTA's potential for monitoring progression. Despite methodological heterogeneity, OCTA complements structural assessments, providing actionable insights for early glaucoma detection. Standardization of protocols and longitudinal validation are needed to optimize clinical utility. These findings support OCTA's role in enhancing risk stratification for glaucoma suspects.