Abstract
Purpose :
Nonarteritic anterior ischemic optic neuropathy (NAION) and optic neuritis are the two most common acute optic neuropathies. OCT angiography is a new tool that can evaluate the density of the radial peripapillary capillary network, which has been shown to be decreased in various chronic optic neuropathies. The goal of this study was to evaluate OCT and OCT angiography’s ability to differentiate optic neuritis and NAION, and predict visual outcomes.
Methods :
We performed a cross-sectional, observational study of patients with unilateral optic neuritis or NAION who presented between 2015 and 2016. Patients were included if they had unilateral optic neuritis or NAION and had OCT (Cirrus) and OCT angiography (Optovue) done at least 3 months after onset. Because a normative database for OCT angiography has not been established, we used the inter-eye difference as an approximation of change. The retinal nerve fiber layer (RNFL) and peripapillary vessel density were compared between optic neuritis and NAION using paired t test. The correlation between OCT parameters and visual outcome [Humphrey visual field mean deviation (MD)] was evaluated with Pearson correlation (R).
Results :
A total of 27 patients were included(11 NAION and 16 optic neuritis). The peripapillary vessel density was more affected in NAION compared to optic neuritis, which showed an average inter-eye difference of 11.4 and 6.9 respectively (p=0.02), while the RNFL was equally affected in the two groups with an average difference of 23.4 and 22.3 respectively (p=0.46). The ratio RNFL/MD differentiated the two groups the best where optic neuritis had an average ratio of 17.9 while NAION had an average ratio of 1.9 (p<0.001).
The overall inter-eye difference in the peripapillary vessel density was correlated with MD (R=0.72, p<0.001) while the RNFL was not correlated (R= 0.25, p=0.22). In the NAION group, the peripapillary vessel density and RNFL were both correlated with MD with a R of 0.80 (p=0.003) and 0.63 (p=0.04) respectively. In the optic neuritis group, the peripapillary vessel density was correlated with MD (R= 0.62, p=0.02), while the RNFL was not correlated (R=0.12, p=0.68).
Conclusions :
Thinning of the RNFL in the setting of preserved visual fields is the most sensitive parameter in differentiating optic neuritis and NAION. The peripapillary vessel density on OCT angiography may better predict visual outcomes, especially in patients with optic neuritis.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.