From the American Academy of Ophthalmology

This analysis of data from the Blue Mountains Eye Study assessed the relationship between baseline retinal vessel caliber and the incidence of open-angle glaucoma over 10 years.  They found that those in the lowest quartile of retinal arteriolar caliber at baseline had around a 4-fold higher risk of developing glaucoma compared with those in the highest quartile of arteriolar caliber, independent of other systemic and ocular glaucoma risk factors, including IOP or ocular perfusion pressure. For each standard deviation decrease in central retinal artery equivalents, there was an approximate 80 percent increased risk of open-angle glaucoma. Ophthalmology, January 2013