Abstract
Purpose :
To quantify peripapillary microvascular defects from optical coherence tomography angiography (OCTA) en face optic nerve head images of the retinal nerve fiber layer, and to correlate microvascular perfusion defects with visual field defects.
Methods :
19 eyes with primary open angle glaucoma (POAG) and with spectral domain (SD)-OCTA scans of signal strength ≥6 (out of 10) and reliable Humphrey Visual Fields (HVFs) 24-2 (Carl Zeiss Meditec; Dublin, CA) were selected for this study. Volumetric peripapillary retina scans were segmented using a prototype semi-automatic segmentation software, to generate en face images of the retinal nerve fiber layer (Figure 1). These were then quantified using prototype software, measuring vessel area density (VAD), vessel complexity index (VCI), and vessel skeleton density (VSD) for the superior and inferior peripapillary regions. Mean deviations (MD) were calculated for superior and inferior hemifields in each eye using proprietary formulas (Carl Zeiss Meditech, Dublin, CA.). Strength of correlation between each perfusion parameter and the corresponding hemifield MD was determined using Spearman’s rank correlation.
Results :
On HVF, 5 eyes had superior hemifield defects, 4 eyes had inferior hemifield defects, and 10 eyes had both. Correlations between hemifield perfusion parameters and corresponding hemifield visual field defects were strongest for VAD (rho=0.4509, p=0.05) and VSD (rho=0.5088, p=0.02) in the superior RNFL and inferior visual field. Inferior RNFL and superior hemifield defects on HVF also had strong correlations for VCI (0.3754) and VSD (0.2947), although these were not statistically significant (p=0.11 and p=0.22, respectively).
Conclusions :
VAD, VCI, and VSD are perfusion parameters on OCTA that correlate well with visual field defects on HVF. The strongest correlations were seen between superior RNFL parameters and inferior field defects. OCTA may be a valuable alternative or supplement to HVF and OCT RNFL measurements for identifying glaucomatous changes in patients with POAG.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.