Retinal blood flow and nerve fiber layer measurements in early-stage open-angle glaucoma

PURPOSE: To evaluate the relationship between retinal circulatory abnormalities and retinal nerve fiber layer (RNFL) thinning in early,stage open angle glaucoma (OAG) to help elucidate the mechanisms underlying the development of glaucomatous optic neuropathy. DESIGN: Prospective cross-sectional. METHODS: Twelve patients with early OAG and a known maximum untreated intraocular pressure less than 22 mm Hg (age, 61.4 +/- 9.7 years; Humphrey visual field mean deviation -2.7 +/- 2.1) and eight age,matched healthy control subjects (age, 58.5 +/- 8.3 years) were included in the study. Blood column diameter, centerline blood speed, and retinal blood flow were measured in the major inferior temporal retinal artery using a Canon laser Doppler blood flow instrument (CLBF 100; Canon, Tokyo, Japan). Peripapillary RNFL thickness was mea, sured using a Stratus optical coherence tomography instrument. RESULTS: On average, there were significant reductions in retinal blood speed (P = .009) and flow (P = .010) in OAG patients compared to controls. The RNFL was significantly thinner in the OAG patients compared to controls (P = .002). There were significant inverse correlations between retinal blood flow and average RNFL thickness and RNFL thickness in the inferior quadrant within the glaucoma group (Rsq = 0.50, P = .01; Rsq = 0.62, P = .003). CONCLUSION: The results showed that a thinner RNFL was associated with a higher retinal blood flow in patients with early-stage OAG. The mechanisms under, lying this phenomenon remain to be elucidated.