Effect of Brimonidine on Retinal Vascular Autoregulation and Short-Term Visual Function in Normal Tension Glaucoma

Citation:

Feke GT, Bex PJ, Taylor CP, Rhee DJ, Turalba AV, Chen TC, Wand M, Pasquale LR. Effect of Brimonidine on Retinal Vascular Autoregulation and Short-Term Visual Function in Normal Tension Glaucoma. Journal of Ophthalmology. In Press.

Abstract:

PURPOSE: To assess whether brimonidine 0.15% alters retinal vascular autoregulation (RVA) and short-term visual function in normal tension glaucoma (NTG) patients who demonstrate retinal vascular dysregulation (RVD). DESIGN: Non-randomized clinical trial. METHODS: In this prospective study, 46 NTG patients not previously treated with brimonidine underwent retinal vascular autoregulation (RVA) testing and visual function assessment using frequency doubling technology (FDT) perimetry and equivalent noise motion sensitivity testing. We measured blood flow in a major temporal retinal artery with subjects seated and then while reclined for 30 minutes using a Canon Laser Blood Flowmeter. Patients having a change in retinal blood flow with posture change outside the range previously found in healthy subjects were classified as having RVD. They were treated with brimonidine 0.15% for eight weeks and designated for re-testing. RESULTS: 23 of the 46 patients demonstrated RVD at the initial visit. Logistic regression analysis indicated that younger age (p=0.050) and presence of diabetes (p=0.055) were marginally significant risk factors for RVD. 17 patients with RVD completed the study (5 withdrew due to brimonidine intolerance; one was not re-tested due to technical issues). Fourteen of the 17 showed a return of the posture-induced change in retinal blood flow to levels within the range consistent with normal RVA (p<0.0001) following brimonidine. We found no significant changes in FDT perimetry or in motion detection parameters following treatment (p>0.09 for all tests performed). CONCLUSIONS: Brimonidine significantly improved impaired RVA in NTG patients, but short-term alteration in visual function could not be demonstrated.