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Barbara Cortes, Shelley Mo, Toco Yuen Ping Chui, Richard B Rosen; Peripapillary Perfused Vessel Density of Major Vessels and Capillaries in Normal Tension Glaucoma. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2006.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the peripapillary perfused vessel density (PVD) in Normal Tension Glaucoma patients (NTG) and normals using Optical Coherence Tomography Angiography (OCTA).
A retrospective analysis of OCTA images obtained using a spectral-domain OCT system (Avanti RTVue-XR, Optovue) was conducted for NTG patients and normals. The OCTA images used were of a layer extending from the inner limiting membrane (ILM) to the posterior of the retinal nerve fiber layer (RNFL) (Fig. A1 & B1). NTG patients were separated into 3 groups: mild, moderate, and severe. A custom designed image analysis method was used to quantify perfused vessel density of capillaries and major vessels in 4 different quadrants (nasal, temporal, superior, and inferior) centered at the optic disc, as well as the annulus (Scripsema et al. IOVS 2016). The annulus was defined as the area between two concentric circles centered at the optic disc, with diameters of 1.95 mm and 3.45 mm. Capillary PVD was defined as the ratio of the area occupied by capillaries in the region of interest (ROI) to the total area of the ROI, excluding the area of the ROI occupied by major vessels. Major vessel PVD was defined as the ratio of the area occupied by major vessels in the ROI to the total area of the ROI (Fig. A2 & B2). Capillary PVD and major vessel PVD for each ROI were compared across all 4 groups using one-way ANOVA and post-hoc Tukey.
A group of 4 normals and 3 groups of NTG, consisting of 4 patients with either mild, moderate, or severe, were included. In the nasal quadrant of the RNFL, capillary PVD decreased for each NTG group, with significant differences for severe NTG (10.67% difference, p<0.01). In the superior, inferior, and temporal quadrants, capillary PVD significantly decreased for severe NTG (p<0.01, p<0.05, and p<0.01 respectively). In the annular ROI, capillary PVD decreased for each NTG group, with significant differences between moderate and severe NTG (5.97% difference, p<0.05). No significant differences in major vessel PVD were found.
OCTA is a useful tool for detecting changes in the perfusion density of several regions in the peripapillary capillary layer of NTG patients, and provides valuable insight on how NTG severity impacts vasculature in the retina.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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