Improved discrimination between normal-tension and primary open-angle glaucoma with advanced vascular examinations - the Leuven Eye Study

Purpose Vascular factors have been suggested to influence the development and progression of glaucoma. They are thought to be especially relevant for normal-tension glaucoma (NTG) patients. We aim to investigate which vascular factors, including advanced vascular examinations, better describe patients with NTG comparing to those with primary open-angle glaucoma (POAG). Methods The Leuven Eye Study database (182 NTG and 202 POAG patients; similar structural and functional damage) was used to compute three multivariate logistic regression models: a conventional model (conventional parameters only, including vascular-related self-reported phenomena, such as migraine or peripheral vasospasm); an advanced vascular model (advanced vascular parameters only: colour Doppler imaging (CDI), retinal oximetry, ocular pulse amplitude and choroidal thickness); and a global model, in which both types of parameters were allowed. Receiver operating characteristic (ROC) curves and corresponding areas under the curve (AUC) were calculated and compared between models. Results Patients with NTG had a higher resistive index and lower early systolic acceleration (ESA) in their retrobulbar vessels and a smaller arteriovenous retinal oxygen saturation difference. The global model (AUC 0.743) showed a significantly better discriminative ability when compared to either the conventional (AUC 0.687, p = 0.049) or the advanced vascular (AUC 0.677, p = 0.005) models. Also, the conventional and the advanced vascular models showed a similar discriminative ability (p = 0.823). Conclusion Patients with NTG have more signs of vascular dysfunction. Clinical conventional parameters, such as asking simple vascular-related questions, combined with advanced vascular examinations provide information to better understand the value that non-IOP-related factors play in NTG.