Glaucoma and cerebral blood flow autoregulation: Pilot study

Abstract

Glaucoma is a leading cause of irreversible blindness worldwide. Although high tension glaucoma (HTG) is associated with increased intraocular pressure, the causes of normal tension glaucoma (NTG) are controversial. We hypothesize that NTG can be related with disturbed cerebral blood flow, therefore, our objective was to explore cerebrovascular autoregulation (CA) status in glaucoma patients. Pilot study of non-invasive CA monitoring included 10NTG patients, 8HTG patients and 10 volunteers in control group. All participants were 63–80 y/o. CA status was monitored by using non-invasive ultrasonic CA monitoring technology based on intracranial blood volume (IBV) slow-wave measurement. Real-time recording of volumetric reactivity index (VRx(t)) was used in order to identify dynamics of CA changes. VRx(t) reflects a time dependence of a phase shift between non-invasively measured IBV(t) and arterial blood pressure ABP(t) slow-waves. Mean values of VRx(t) and SD were as follows: control mVRx = −0.179, SD = 0.22; NTG mVRx = 0.056, SD = 0.168 and HTG mVRx = −0.070, SD = 0.249 (Fig. 1). Statistically significant differences were found in comparing mVRx indexes as well as duration of longest CA impairment events in NTG and control group (Mann-Whitney U tests P = 0.025 and P = 0.007, respectively). However, these differences were not significant in HTG and control group. By using this non-invasive technology, it has been shown for the first time that CA status is deteriorated in NTG patients and that mean VRx(t) values are statistically significantly different comparing NTG and control groups. We didn't find statistically significant difference between HTG and control group.