Retinal Vessels in Patients with Multiple Sclerosis: Baseline Diameter and Response to Flicker Light Stimulation

Background: Transparency of ocular media enables the precise quantitative analysis of vessels of retina, a neuronal tissue which can be affected by multiple sclerosis (MS). Patients and Methods: Eyes with no history of optic neuritis (non-ON eyes) of 21 patients with MS were examined with Retinal Vessel Analyzer. Segments of vessels of 500 mu m length were measured proximal and distal from the optic disc and compared to those of 21 age- and gender-matched controls. Baseline diameters and peak response to flicker light stimulation of retinal vessels were analyzed. Results: MS eyes had thinner arterioles (p=0.02) and thicker venules (p=0.008) than controls: arterioles 111 +/- 14 mu m (proximal), 99 +/- 11 mu m (distal) in MS eyes and 121 +/- 15 and 107 +/- 9 in controls, respectively. Values for venules were 157 +/- 18 and 136 +/- 20 (MS); 147 +/- 15 and 119 +/- 20 (controls). Peak response was higher in MS eyes than in controls for arterioles (p=0.007), but comparable for venules (p=0.35). Conclusion: Narrower arterioles and wider venules might be a consequence of subclinical swelling of optic nerve axons in eyes with negative history of ON in MS patients.