The research protocols were approved by the Institutional Review Board at Oregon Health & Science University, performed in accord with the tenets of the Declaration of Helsinki. This prospective observational study was performed from July 24, 2013, to April 17, 2014, at Casey Eye Institute, Oregon Health & Science University. Correlation of these perfusion indexes with more conventional measures of glaucoma (VF and structural OCT) was also investigated. We compared the perfusion indexes between normal and glaucomatous eyes. For this study, we obtained OCT angiograms of the peripapillary retina on a commercially available spectral OCT system and quantified peripapillary flow index and peripapillary vessel density using the SSADA algorithm. To our knowledge, no attempt has been made to evaluate the peripapillary retinal vasculature using OCT in glaucomatous eyes. 20, 22– 27 Jia et al 18 recently quantified optic disc perfusion using the split-spectrum amplitude-decorrelation angiography (SSADA) algorithm on a custom swept-source OCT system and showed decreased optic disc perfusion in glaucoma. Laser Doppler flowmetry (LDF) and laser speckle flowgraphy (LSFG) have demonstrated reduced optic nerve head (ONH) and peripapillary blood flow dynamics in glaucoma. Some studies 15– 21 have shown that glaucoma may be associated with vascular dysfunction, suggesting another possible imaging target for early diagnosis and monitoring of glaucoma. 4, 5 Structural studies 6– 14 of retinal nerve fiber layer (NFL) by optical coherence tomography (OCT) show its promise as an objective quantifiable measure for glaucoma assessment, but it has limited sensitivity for detecting early glaucoma and only moderate correlation with VF loss. Visual field (VF) testing remains the criterion standard for glaucoma assessment, but it has substantial variability, with poor reproducibility in some patients. 1– 3 Early diagnosis and close monitoring of glaucoma are important given the insidious onset of glaucoma, with irreversible nerve damage associated with vision loss. Glaucoma is the second leading cause of blindness worldwide, affecting more than 60 million people and predicted by 2020 to reach 79.6 million. The areas under the receiver operating characteristic curve for normal vs glaucomatous eyes were 0.892 for peripapillary flow index and 0.938 for peripapillary vessel density. Peripapillary flow index (Pearson r = −0.808) and peripapillary vessel density (Pearson r = −0.835) were highly correlated with visual field pattern standard deviation in glaucomatous eyes ( P =. Peripapillary flow index and peripapillary vessel density in glaucomatous eyes were lower than those in normal eyes ( P <.
In normal eyes, between-visit reproducibilities of peripapillary flow index and peripapillary vessel density were 4.3% and 2.7% of the coefficient of variation, respectively, while the population variabilities of peripapillary flow index and peripapillary vessel density were 8.2% and 3.0% of the coefficient of variation, respectively. In 12 glaucomatous eyes, this network was visibly attenuated globally and focally. In 12 normal eyes, a dense microvascular network around the disc was visible on OCT angiography.
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