Abstract
Purpose :
Non-arteritic anterior ischemic optic neuropathy (NAION) and primary open-angle glaucoma (POAG) both damage retinal ganglion cell axons, which are perfused by the radial peripapillary capillaries. To further evaluate the ischemic nature of NAION, we compared peripapillary capillary density (PCD) in NAION eyes to POAG eyes matched for visual field mean deviation (MD) and retinal nerve fiber layer thickness (RNFLT).
Methods :
31 chronic NAION (>6 months after acute event) and unaffected fellow eyes (31 subjects) 30 severe POAG eyes (20 subjects), and 77 control eyes (46 healthy subjects) were imaged on a commercial optical coherence tomography angiography system (AngioVue, Avanti RTVue-XR, Optovue, CA), producing 4.5mm×4.5mm images centered on the optic nerve head. Two concentric circles of diameters 1.95mm (inner) and 3.45mm (outer) were manually placed, producing an annular region-of-interest of width 0.75mm. Image analysis with major vessel removal was performed using a custom MATLAB program (The Mathworks, Inc., Natick, MA). Whole-image PCD, whole-annulus PCD, and sectoral PCD were measured. A linear mixed model was used to compare PCD among groups and account for inter-eye correlation and multiple comparisons.
Results :
Whole-image and whole-annulus PCD in NAION (30.1±6.0% and 29.7±6.5%, respectively) and severe POAG (28.9±4.8% and 29.7±5.2%, respectively) eyes were significantly decreased compared to unaffected fellow eyes (41.6±4.5 and 42.3±5.0) and control eyes (42.3±2.3% and 43.9±2.1%) (all P<0.001). Whole-image and whole-annulus PCD were not statistically different between NAION and severe POAG eyes (both P=0.99). However, POAG eyes exhibited greater superior PCD loss compared to NAION eyes (P<0.01). In contrast, NAION eyes exhibited greater inferior PCD loss compared to POAG eyes (P<0.01). In all study eyes, whole-image PCD was significantly correlated to both MD and RNFLT (r=0.79 and r=0.72, respectively, both P<0.001).
Conclusions :
Whole-image PCD and annular PCD were affected to similar degrees in chronic NAION and severe POAG, suggesting that independent of the type of optic nerve damage, PCD loss may mirror retinal ganglion cell axonal damage.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.