Rigidity of Retinal Vessels in Patients with Multiple Sclerosis

Purpose: The aim of this study was to analyze pulse wave propagation in the ocular circulation by assessing the phase delay between retinal arterioles and venulles and calculating the pulse delay between the retinal and choroidal circulations in MS patients and in control subjects. Subjects and Methods: Twenty patients with multiple sclerosis (38.3 +/- 6.2 years) and twenty healthy subjects (37.4 +/- 15.2 years) were examined with the Retinal Vessel Analyzer. In addition, an average peripapillary RNFL (retinal nerve fiber layer) thickness was measured by means of ocular coherence tomography in MS patients. The phase delay between the arteriole and venule pulsations was assessed at three sites: in the close retinal vicinity of the disc, 1 - 2 disc diameters and 3 - 4 disc diameters away from the disc. Assuming that venules are counterphased to the choroidal circulation, a choroid-to-retina pulse delay was calculated. Results: The choroid-to-retina pulse delay was 0.26 +/- 0.11, 0.27 +/- 0.13 and 0.34 +/- 0.15 sec in eyes with history of optic neuritis (ON-eyes); in eyes of MS patients without such a history (non-ON eyes) the corresponding values were 0.27 +/- 0.14, 0.29 +/- 0.11 and 0.30 +/- 0.15 sec, and in controlal vessel rigidity was significantly correlated with the interocular difference in RNFL thickness in MS patients. eyes 0.32 +/- 0.19, 0.38 +/- 0.16 and 0.45 +/- 0.20 sec, respectively, at three sites centrifugal from the disc. The choroid-to-retina pulse delay was significantly longer in healthy control eyes than both in ON eyes (p=0.012) and non-ON eyes of MS patients (p=0.004). The interocular difference of the choroid-to-retina pulse delay and OCT RNFL thickness showed a significant correlation in MS patients (Pearson r=0.54, p=0.015; Spearman R=0.66, p=0.0016). Conclusion: Patients with multiple sclerosis seem to demonstrate an increased rigidity of the retinal vessels. The interocular difference in retinal vessel rigidity was significantly correlated with the interocular difference in RNFL thickness in MS patients.