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Betty A Situ, Ryuna Chang, Zhongdi Chu, Alena Reznik, Sahar Bedrood, Ruikang K Wang, Grace Richter; Quantifying Peripapillary Microvasculature Changes Before and After Trabeculectomy Using Optical Coherence Tomography Angiography. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5069.
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© ARVO (1962-2015); The Authors (2016-present)
To measure changes in peripapillary microvasculature after IOP reduction using spectral-domain optical coherence tomography angiography (SD-OCTA)
We analyzed 6mmx6mm SD-OCTA images centered on the optic nerve head in primary open-angle glaucoma patients who underwent trabeculectomy at the USC Roski Eye Institute (n=7). OCTA images were taken pre- and post- operatively with the Zeiss AngioPlex. Manual segmentation of volumetric OCTA data was performed to generate en face vasculature projections of the retinal nerve fiber layer (RNFL). Images were quantified using prototype software to measure the following perfusion parameters globally, and in clock-hour sectors (from 2.8mm radius annulus excluding disc): vessel area density (VAD), vessel skeletal density (VSD), vessel complexity index (VCI), flow impairment (FI) zones, and flux. Sector data was evaluated in specific anatomic zones. Paired t-tests were used for statistical analysis.
7 eyes from 6 patients were analyzed. Mean IOP reduction was 56.6% at the time of post-operative imaging (mean 6.5 weeks post-operatively). Global VCI in the RNFL increased 8% (p=0.03), FI zones decreased 33% (p=0.02), and there was a trend towards improved perfusion for VAD, VSD, and flux (ps>0.05). Combined clock-hour data showed that VCI increased 7% (p=.00002), FI zones decreased 24% (p=.001), and flux increased 3% (p=.00002).Clock-hour 1 showed increased VCI (22%, p=0.02) and flux (5%, p=0.01), and decreased FI zones (24%, p=.001). Clock-hour 2 showed decreased FI zones (42%, p=.02) and increased flux (5%, p=.02). Clock-hours 5 and 10 had modest increases in VCI (7%, p=.02 and 9%, p=.001). Clock-hours 6 and 7 had increased VAD (6%,p=.004 and 8%, p=.04). Clock-hours 11 and 12 showed increased VAD (12%, p=.003 and 17%, p=.02), VCI (18%, p=.002 and 29%, p=.002), VSD (12.9%, p=.007 and 15%, p=.02), and flux (7%, p=.01 and 8%, p=.02). All other clock hour-specific perfusion was not significantly improved.
RNFL peripapillary perfusion improved in glaucoma patients after trabeculectomy and was most pronounced in the inferotemporal regions. Comparing focal anatomic regions side-by-side improved detection of perfusion changes.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Figure 1. 6mmx6mm en face image of optic nerve head (a.); map of clock hour sectors (b.) for quantification (shown for OD; OS sectors reflected on vertical axis).
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