Abstract
Purpose :
NAION presents with acute onset of painless vision loss and affects 2.3-10.3 people per 10000 in the US. The mechanism of NAION is unknown. Further understanding of the disease will allow us to potentially develop novel treatments and better identify patients at risk. OCT-A is a non-invasive infrared laser which constructs a cross sectional image of the retinal vasculature to quantitatively measure blood flow. In this study we use OCT-A to better understand the retinal vasculature in NAION.
Methods :
This is an IRB approved (STU00200890) prospective case control study including patients diagnosed with NAION from 2007-2017 at Northwestern Memorial Hospital. Patients were included without other eye disease, 45 years old or greater, and a documented eye exam within the last 12 months. Study participants had fundus photos and OCT-A imaging studies.
Results :
7 of the 9 patients had one unaffected eye and were included in the analysis. The mean age was 59 years old (range 46-66), 83% were male. 57% had obstructive sleep apnea, 29% had hyperlipidemia, 29% had hypertension and 43% had hyperlipidemia. The time elapsed since diagnosis was an average of 24 months (range 13-40 months). Statistical analysis was performed with a paired student-t test. The adjusted flow index (AFI) was significantly decreased at the optic nerve head (ONH, mean 0.42+/-0.07 vs 0.49+/-0.06, p<0.001) and retinal peripapillary capillary (RPC, mean 0.37+/-0.06 vs 0.45+/-0.06, p=0.02) in the affected eye. The vessel length density was significantly decreased at the ONH (mean 0.36+/-0.05 vs 0.44+/-0.03, p=0.03), RPC (0.34+/-0.05 vs 0.47 +/-0.06, p=0.008) and vitreous (mean 0.27+/-0.05 vs 0.40+/-0.05, p=0.009). The number of vessel intersections were significantly decreased at the ONH (mean 656 +/-143 vs 1142+/-165, p=0.001), RPC (mean 583+/-153 vs 1984 +/-1280, p=0.02) and vitreous (mean 256+/-87 vs 572+/-145, p=0.01).
Conclusions :
This study shows that the peripapillary microvasculature is damaged in patients with NAION in the ONH and RPC layers. As this is a cross sectional study we cannot infer cause and effect; however, these data support the hypothesis that impaired circulation of blood to the optic nerve may be involved in the pathogenesis of NAION.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.