Ocular Blood Flow in Glaucoma: The Leuven Eye Study

Impaired Ocular Blood Flow in Glaucoma

Current glaucoma treatment strategies aim to delay disease progression by reducing one the main risk factors for this disease, intra-ocular pressure (IOP). However, in a significant number of patients, IOP-reduction alone is not enough to halt or adequately slow disease progression, suggesting that other factors may be involved in the disease process.

One possibility is that underlying vascular dysfunction in patients with glaucoma may further aggravate ganglion cell damage. In fact, extensive literature provides support that patients with glaucoma have signs of ocular and systemic vascular abnormalities.

However, a large ocular blood flow oriented trial to integrate these findings in the clinical setting is lacking. To address this gap, Belgian researchers from the Department of Ophthalmology at University Hospitals Leuven, undertook a prospective study to help identify vascular data that might be used as a clinical tool for screening and disease stratification (1).

Design and Methods
 
Patients with primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG), ocular hypertension (OHT), glaucoma suspects and healthy volunteers were recruited for this prospective, cross-sectional, case-control, hospital-based study.

In addition to a comprehensive ophthalmological examination, a vascular-oriented questionnaire was completed and ocular blood flow assessment was performed using: color Doppler imaging of retrobulbar vessels, retinal oximetry, dynamic contour tonometry, and optical coherent tomography enhanced-depth imaging of the choroid.

Results

A total of 614 subjects (291 males) were recruited between March and December 2013 (POAG: 214, NTG: 192; OHT: 27; glaucoma suspect: 41; healthy controls: 140). Glaucoma groups (NTG and POAG) were age and gender matched with the control group (p > 0.05). Glaucoma groups were paired In terms of functional and structural parameters (p > 0.08).

Mean ocular perfusion pressure was higher in the glaucoma groups than in controls (p < 0.001). Glaucoma groups had lower retrobulbar velocities (see table 3), higher retinal venous saturation and choroidal thickness asymmetries compared to the healthy group, in line with the current literature.

Graph courtesy of Acta Ophthalmologica

 Comments

The Leuven Eye Study stands as one of the largest clinical trials on ocular blood flow and appears to be adequately powered. The study team created a database of 600+ patients over a 9-month period, and spanning over five groups (healthy controls, POAG, NTG, ocular hypertension and glaucoma suspects).

Encompassing over 100 variables, the database may help integrate the vascular aspects of glaucoma into the clinical practice of glaucoma according to the study authors.

References
 

1. Pinto LA et al. Ocular blood flow in glaucoma – the Leuven Eye Study. Acta Ophthalmol. Published ahead of print, Feb. 19, 2016.