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 microm 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 microm (proximal), 99 +/- 11 microm (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.