Arteriolar Oxygen Saturation, Cerebral Blood Flow, and Retinal Vessel Diameters: The Rotterdam Study
Received 28 February 2007; received in revised form 8 June 2007; accepted 26 June 2007. published online 06 December 2007.
Objective
Retinal vessel diameters, in particular larger venular diameters, have been associated with cerebrovascular disease. Larger retinal venular diameters may reflect cerebral ischemia. The authors investigated whether arteriolar oxygen saturation (SaO2) and total cerebral blood flow (CBF), indicators of cerebral oxygen supply, are associated with retinal arteriolar or venular diameters.
Design
Cross-sectional study performed within the population-based Rotterdam Study.
Participants
Randomly selected participants aged 55 years or older (n = 696), who underwent both an eye examination and brain magnetic resonance imaging (MRI).
Methods
Arteriolar oxygen saturation was determined by pulse oximetry on the right index finger. Cerebral blood flow was assessed using a phase-contrast MRI sequence that measured the flow in the basilar and both internal carotid arteries. Brain volume was measured to express CBF per 100 ml brain volume. Retinal arteriolar and venular diameters were measured on digitized fundus color transparencies on 1 eye of each participant. Regression models were used to investigate the association of SaO2 and CBF with retinal vessel diameters.
Main Outcome Measures
Mean retinal arteriolar and venular diameters (in micrometers).
Results
Lower SaO2 was associated with larger venular diameters. Persons with SaO2 less than 96% (n = 113) had on average 5 μm larger venular diameters compared with those with SaO2 of 96% or more (n = 583; age- and gender-adjusted mean difference, 5.6 μm; 95% confidence interval, 1.2–10.0). Cerebral blood flow was not related to venular diameters when analyzed separately. Additional analyses showed that the association between SaO2 and venular widening was confined to participants within the lowest tertile of CBF. No associations were found between SaO2 or CBF and arteriolar diameters. Additional adjustment for established cardiovascular risk factors did not change the results.
Conclusions
An association of lower SaO2 with larger retinal venular diameters was observed, in particular in the presence of lower CBF. These findings suggest that venular widening may reflect a lower oxygen supply, especially to the brain.
Available online: December 11, 2007.
1Department of Epidemiology and Biostatistics, Erasmus Medical Center, Rotterdam, Netherlands.
2Department of Neurology, Erasmus Medical Center, Rotterdam, Netherlands.
3Department of Radiology, Erasmus Medical Center, Rotterdam, Netherlands.
4Netherlands Institute for Neuroscience, Academic Medical Center, Amsterdam, Netherlands.
5Department of Ophthalmology, Academic Medical Center, Amsterdam, Netherlands.
Correspondence to Monique M. B. Breteler, MD, PhD, Department of Epidemiology and Biostatistics, Erasmus Medical Center, P. O. Box 2040, 3000 CA Rotterdam, Netherlands.
ABSTRACT