Assessment of blood flow velocity in eyeball arteries in multiple sclerosis patients with past retrobulbar optic neuritis in color Doppler ultrasonography

Purpose
The aim of the study was to evaluate blood flow velocity in eyeball arteries in affected and unaffected eyes in patients with past retrobulbar optic neuritis in the course of multiple sclerosis (MS).

Material and methods
Evaluation of blood flow velocity in 16 eyes of 16 patients with unilateral retrobulbar optic neuritis was performed in ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary artery (SPCA). In the arteries the following parameters have been assessed: peak systolic velocity (PSV), end-diastolic velocity (EDV), mean flow velocity (MV), indicators of peripheral vascular resistance such as Gosling Index (PI) and Pourcelot Index (RI). The obtained values have been compared to values of blood flow in the same arteries of the control group. Using Shapiro-Wilk test, mode of distribution of each parameter was analyzed. The statistic analysis has been done between group of affected eyeballs (group 1) and control group and between group of unaffected eyeballs (group 2) in multiple sclerosis patients and control group (13 individual, 26 eyes), regarding the age. The assessment was performed with the assistance of t-Student test, and in case of lack of normal distribution, by U Mann-Whitney test. Statistically significant difference was established when p value was below 0.05 (p≤0.05).

Results
Among the analyzed parameters of blood flow velocity, statistically significant disturbances in the examined eyeball arteries were found. The most significant disturbances of blood flow were found in CRA and SPCA. The affected parameters were: diminished MV velocity in OA; PSV, MV, RI in CRA and PSV, EDV, MV and RI indices in SPCA. The similar blood flow velocity disturbances were also found in unaffected eyeball arteries

Conclusions
In MS patients with past optic neuritis disturbances of ocular circulation can be observed. The statistically significant diminishing blood flow velocity parameters and vascular resistance indices in eyeball arteries may indicate alterations of blood flow. Lowering of systolic and mean velocities and resistance indices of blood flow are most expressed in CRA and SPCA. Reduction in blood flow parameters in the examined arteries occur both, in the eyes previously affected by past optic neuritis and in contra lateral, unaffected eyes.