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Davis B. Zhou, Maria V. Castanos, Jorge Santiago Andrade Romo, Melvi Eguia, Erica B. Jacobs, Donald C Hood, Robert Ritch, Richard B Rosen, Toco Yuen Ping Chui; Dissecting Neural and Vascular Contributions to Glaucoma Progression Using En Face OCT-Reflectance and OCT-Angiography. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6155.
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© ARVO (1962-2015); The Authors (2016-present)
Peripapillary retinal nerve fiber bundles (RNFB) and their supporting microvascular networks have become accessible using en face OCT-reflectance (OCT-R) and OCT-angiography (OCT-A). We assess and compare the neural and vascular change over time in patients with glaucomatous damage.
Ten eyes of 9 primary open-angle glaucoma patients with arcuate visual field defects were imaged using a SDOCT system (Avanti RTVue-XR; Optovue). Six eyes were subsequently imaged 10-28 months afterwards. Ten 4.5x4.5mm peripapillary OCT-R and respective OCT-A scans were obtained at each visit. Scans were then registered and averaged per patient with ImageJ (PMID:28068370). OCT-R and respective OCT-A slabs located between the inner limiting membrane and nerve fiber layer were used for image analysis. Neural defect progression was evaluated by measuring the difference in RNFB defect width on the averaged and polar transformed OCT-R scans between visits (Fig A-C). Vascular nonperfusion over time was evaluated by measuring the perfusion density difference on the averaged OCT-A scans between visits (Fig D-F). OCT-R and OCT-A were also compared to the 24-2 visual field tests for each patient. Progression on visual field tests was defined as an increase in the number of points with <1% total deviation between visits.
The mean±SD of RNFB defect and vascular nonperfusion progression was 1.4±1.3° and 9.2±4.8% per year, respectively. Four out of six eyes displayed RNFB defect progression and all six eyes showed vascular nonperfusion over time. Three eyes demonstrated no progression on 24-2 visual field testing but displayed RNFB defect change and vascular nonperfusion of 1.2±1.5° and 7.5±5.9% per year, respectively. Two patients with no significant RNFB defect progression demonstrated vascular nonperfusion over time of 6.4±3.8% per year.
OCT-R and OCT-A show promise for tracking subtle glaucoma progression of RNFB defects and vascular nonperfusion. There were measurable subclinical changes in neural and vascular components before further vision loss could be detected on 24-2 visual field tests. Further assessment of structure-function relationships in glaucoma will help to enhance our understanding as to whether neural and vascular changes may occur simultaneously or separately.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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