Reduced cerebrovascular blood flow velocities and vasoreactivity in open-angle glaucoma

This study was conducted at the Indiana University Hospital, Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana.
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Abstract

Purpose

To compare cerebral blood flow velocities between open-angle glaucoma (OAG) patients and controls, at baseline and during hyperoxia.

Design

Observational cohort study.

Methods

A prospective study was conducted in a single institution. Sixteen OAG patients and 15 normal subjects, matched for age, were enrolled. Patients and controls were studied at baseline, while breathing room air, and during 100% oxygen breathing. The eye with the more severe visual field defect was chosen in glaucoma patients, while in controls, the study eye was chosen randomly. Subjects with history of diabetes, cardiovascular, or respiratory disease were excluded. Measurements included brachial arterial pressure, heart rate, intraocular pressure and transcranial Doppler (TCD). Mean and peak velocity and pulsatility index of the ipsilateral middle cerebral artery (MCA) were measured by TCD.

Results

At baseline, MCA mean and peak systolic blood flow velocities were significantly lower in glaucoma patients compared with controls (mean velocity: 50.2 vs 65.3 cm/s, P < .05; peak velocity: 74.2 vs 96.8 cm/s, P < .05). Additionally, while hyperoxia significantly decreased both mean and peak systolic velocities in MCA of controls (mean velocity: 65.3 vs 57.7 cm/s, P < .05; peak velocity 96.8 vs 87.9 cm/s, P < .05), it did not cause any significant change in OAG patients.

Conclusion

Glaucoma patients were found to have lower MCA blood flow velocities and an absence of vasoreactivity to hyperoxia, compared with controls. The relationship of these cerebral hemodynamic abnormalities to glaucoma pathogenesis and progression remains to be explored.

Section snippets

Design

The study design was a nonrandomized observational cohort study.

Setting

The study was conducted at the University Hospital Ophthalmology Clinic at the Indiana University School of Medicine, Indianapolis.

Study population

Sixteen OAG patients and 15 normal subjects were enrolled in this study. The two groups were matched for age (mean age 60.8 ± 10.5 years for glaucoma patients, 53.7 ± 10.2 years for controls). Patients were described as suffering from OAG on the basis of characteristic optic nerve damage as well as visual field defect, regardless of the IOP. According to the

Results

Glaucoma patients and controls= were similar in systolic arterial BP and HR at baseline and during hyperoxia (Table 1). Diastolic blood pressure was significantly lower in controls than in glaucoma patients at baseline and during hyperoxia (Table 1). Intraocular pressure was statistically significantly higher in glaucoma patients both at baseline and during hyperoxia (Table 1). Intraocular pressure was unchanged from baseline during hyperoxia in both groups (Table 1). No change in blood

Discussion

The results of the current study suggest that total cerebral perfusion in OAG patients is reduced in comparison to age-matched controls. Our findings are in agreement with previous magnetic resonance imaging studies suggesting reduced total cerebral perfusion in normal tension glaucoma patients.10, 11 Normal tension glaucoma patients exhibit confluent deep white matter lesions known to be associated with decreased total cerebral perfusion.12, 13 Although mean velocity in the MCA is not a direct

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