Optic nerve blood flow is diminished in eyes of primary open-angle glaucoma suspects

PURPOSE: The purpose of this study was to evaluate optic nerve blood flow i n primary open angle glaucoma suspect eyes with normal automated visual fie lds, in an attempt to elucidate how early in the glaucomatous disease proce ss changes in optic nerve blood now become apparent. METHODS: Twenty-one eyes (21 patients) suspected of having primary open-ang le glaucoma were studied prospectively and compared with a previously repor ted cohort of 22 eyes (22 patients) with primary open-angle glaucoma and 15 eyes (15 subjects) of age-matched controls. Primary open-angle glaucoma su spect eyes had untreated intraocular pressure greater than 21 mm Hg and nor mal visual fields using Humphrey program 24-2 or 30-2 with a full threshold strategy. Laser Doppler flowmetry was used to measure optic nerve head blo od velocity, volume, and flow at four quadrants in the optic nerve, in the cup, and in the foveola of one eye of each patient. The mean flow from the superotemporal rim, inferotemporal rim, and cup was calculated (Flow(3)) an d identified as the main outcome measure. Measurements from primary open-an gle glaucoma suspect eyes were compared with corresponding measurements fro m controls and eyes with primary open-angle glaucoma; a Student t test was employed with a Bonferroni corrected P value of .025 to account for compari sons of primary open angle glaucoma suspects both to controls and to eyes w ith primary open-angle glaucoma. RESULTS: Compared with controls, Flow(3) was 24% lower in primary open-angl e glaucoma suspect eyes (P < .0003). In primary open-angle glaucoma suspect eyes, flow was 16% lower in the superotemporal rim (P < .007), 35% lower i n the cup (P < .007), and 22% lower in the inferotemporal neuroretinal rim (P < .029) compared with controls. No significant difference between primar y open-angle glaucoma suspect and control eyes was seen in the inferonasal rim, superonasal rim, or foveola. No significant difference was detected at any location between primary open-angle glaucoma suspect eyes and eyes wit h primary open-angle glaucoma. CONCLUSIONS: Laser Doppler flowmetry detected circulatory abnormalities in primary open-angle glaucoma suspects who did not have any manifest visual f ield defect. Decreases in flow in glaucoma suspects were similar in magnitu de to those of subjects with primary open-angle glaucoma. These data sugges t that impaired optic nerve blood flow develops early in the glaucomatous p rocess and does not develop solely as a result of glaucoma damage. (Am J Op hthalmol 2001;132: 63-69. (C) 2001 by Elsevier Science Inc. All rights rese rved).