Not long ago, researchers discovered they could accurately assess the vascular health of the choroid with a new measurement known as the choroidal vascularity index (CVI). This number is calculated as the proportion of luminal area (LA) to the total choroid area (TCA)—both measured using optical coherence tomography (OCT).1 Early research suggests this parameter is a better marker of choroidal disease, considering the commonly used measurement of subfoveal choroidal thickness is affected by many physiological variables, while CVI is not.1
A new study now suggests CVI can also help clinicians better differentiate between arteritic anterior ischemic optic neuropathy (A-AION) and non-arteritic anterior ischemic optic neuropathy (NA-AION). A team of Italian researchers found that macular and peripapillary CVIs are reduced in A-AION patients.2
This retrospective, cross-sectional study evaluated the macular and optic nerve head OCT scans of 20 patients with A-AION secondary to giant cell arteritis, 20 patients with NA-AION and 20 control subjects. The team found that patients with A-AION showed significantly lower macular and peripapillary CVIs compared with patients with NA-AION and control subjects. However, they noted that there was no significant difference in macular or peripapillary CVIs between patients with NA-AION and controls. After adjusting for age, the researchers added that the difference in peripapillary CVI between both groups remained statistically significant, while the difference in macular CVI did not.
The study concludes that these parameters may be useful in quantitatively evaluating choroidal vascular dysfunction in A-AION. It may also serve as a new additional diagnostic tool to distinguish A-AION from NA-AION.
1. Agrawal R, Gupta P, Kara-Anne Tan K-A, et al. Choroidal vascularity index as a measure of vascular status of the choroid: Measurements in healthy eyes from a population-based study. Sci Rep. 2016;6:21090.
2. Pellegrini M, Giannaccare G, Bernabei F, et al. Choroidal vascular changes in arteritic and non-arteritic anterior ischemic optic neuropathy. Am J Ophthalmol. April 4, 2019. [Epub ahead of print].