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Ocular blood flow related to cataract development, study finds
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Reduced blood flow velocity to the ophthalmic artery may increase the risk of developing cataract, a prospective study by researchers in Switzerland suggests.
Matthias C. Grieshaber, MD, FEBO, and colleagues at the University Hospital Basel compared the retrobulbar hemodynamics in 30 patients scheduled for cataract surgery to those in 100 healthy control subjects with no lens opacities. The researchers measured blood-flow velocity in the ophthalmic artery using the Siemens Quantum 2000 (Siemens Albis AG), a color Doppler imaging system.
They found that cataract patients had significantly lower peak systolic velocity, end diastolic velocity and mean velocity compared to controls.
Peak systolic velocity averaged 40.5 cm/sec for control subjects and 35.6 cm/sec for cataract patients (P = .016). End diastolic velocity averaged 9.5 cm/sec for controls and 7.4 cm/sec for cataract patients (P = .002), and mean velocity averaged 17.5 cm/sec for controls and 13.7 for cataract patients (P < .001).
No association was seen between peak systolic and end diastolic velocities and the presence of cataract.
"After adjusting for age and systemic mean arterial pressure ... only mean velocity was found to be significantly different between the two groups," the study authors said. "Peak systolic velocity and end diastolic velocity describe unique time points during the cardiac cycle, whereas mean velocity represents an average value for the entire cardiac cycle, and is, therefore, possibly more directly related to bulk blood flow."
A retrospective subgroup analysis of age-matched patients and controls older than 55 years showed that mean velocity was significantly lower in cataract patients (P = .004), and the association was strengthened in a comparison of only age-matched nonsmokers (P = .003).
"Altered blood flow may contribute to inadequate supply of metabolic nutrients to the lens. Alternatively, vascular dysregulation with reperfusion may be a source of free radicals, as has been hypothesized for glaucoma, in particular because oxidation is a hallmark of age-related nuclear cataract," the authors hypothesized.
No association was identified between the severity of lens opacification and mean velocity in the ophthalmic artery.
The study is published in the December issue of the British Journal of Ophthalmology.