Optical Coherence Tomography Angiography (OCTA) Differences in Vessel Perfusion Density and Flux Index of the Optic Nerve and Peri-Papillary Area in Healthy, Glaucoma Suspect and Glaucomatous Eyes

Abstract

Purpose

To assess the ability of vascular perfusion parameters determined by optical coherence tomography angiography (OCTA) to detect and monitor glaucoma.

Methods

This prospective study included healthy, glaucoma suspect and glaucomatous eyes. All eyes underwent comprehensive glaucoma examination, including visual field tests and ocular imaging scans by OCTA. Parameters measured included retinal nerve fiber layer (RNFL) thickness, ganglion cell analysis (GCA), vascular perfusion density (VPD) and flux index (FI) of the optic nerve and peri-papillary area. Ocular parameters in healthy, glaucoma suspect, and glaucomatous eyes were compared by generalized estimating equations (GEE) with adjustments for age, with their relationships analyzed by Pearson’s correlation coefficient. Rates of change per year were compared in glaucomatous eyes with and without glaucoma progression.

Results

This study enrolled 238 eyes, including 56 healthy, 79 glaucoma suspect, and 103 glaucomatous eyes. After adjustments for age, the average VPD (45.40 ± 0.19% vs 45.05 ± 0.22% vs 42.89 ± 0.32%, p < 0.001) and FI (0.4210 ± 0.0055 vs 0.4105 ± 0.0039 vs 0.3801 ± 0.0048, p < 0.001) in these three groups differed significantly. Average VPD in the glaucoma group was inversely associated with the severity of glaucoma, being 43.99 ± 0.32%, 42.63 ± 0.43% and 39.27 ± 0.48% in eyes with early, moderate and severe glaucoma, respectively (p < 0.001). Average VPD, as well as VPD in the superior and inferior quadrants correlated well with both OCT determined RNFL and visual field parameters. The decreases per year in both superior (−0.012 vs −0.001, p = 0.002) and inferior (−0.008 vs −0.003, p = 0.007) FI were significantly greater in glaucomatous eyes with than without glaucoma progression.

Conclusion

Both VPD and FI as measured by OCTA are promising ocular parameters that can distinguish between normal and glaucomatous eyes. VPD is sensitive in comparing eyes at different glaucoma stages, whereas FI can detect rates of glaucoma progression.

Trial Registration

Thai Clinical Trial Registry, TCTR20181031002.

Keywords:

• optical coherence tomography angiography
• vessel perfusion density
• flux index
• glaucoma
• glaucoma suspect
• peri-papillary vasculature

Abbreviations

ANOVA, Analysis of variance; AUROC, Areas under receiver operating characteristic curves; BP, blood pressure; FI, Flux index; GCA, Ganglion cell analysis; GEE, Generalized estimating equation; GPA, Guided Progression Analysis; MAP, Mean arterial pressure; MD, Mean deviate; OCT, Optical coherence tomography; OCTA, Optical coherence tomography angiography; RNFL, Retinal nerve fiber layer; SD, Standard deviation; VFI, Visual field index; VPD, Vascular perfusion density.

Data Sharing Statement

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Ethics Approval and Consent to Participate

Ethical review committee for research in human subjects, Mettapracharak (Wat Rai Khing) Hospital. Written informed consent was obtained from all participants.

Acknowledgments

The authors thank the patients included in this study, as well as the residents, glaucoma fellows, research assistants and ophthalmic technicians in the department of Ophthalmology, Mettapracharak (Wat Rai Khing) Hospital. The authors also thank Miss Wanwisa Sathim, Miss Raphephan Nakuamka and Mr. Wasin Sukphopetch.

Author Contributions

All authors made a significant contribution to the work reported, including whether that is in the conception, study design, execution, acquisition of data, and/or data analysis and interpretation, or in all these areas. The authors also took part in drafting, revising and/or critically reviewing the article; provided final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agreed to be accountable for all aspects of the work.

Disclosure

The authors declare that they have no competing interests.

Additional information

Funding

This work was supported by the Mettapracharak (Wat Rai Khing) Hospital.