Changes in optic nerve head blood flow after therapeutic intraocular pressure reduction in glaucoma patients and ocular hypertensives.

Abstract

To detect and quantify changes in optic nerve head (ONH) and peripapillary retinal blood flow by scanning laser Doppler flowmetry (SLDF) in open-angle glaucoma (OAG) and ocular hypertension (OHT) after therapeutic intraocular pressure (IOP) reduction. Prospective, nonrandomized, self-controlled trial. Twenty patients with OAG and 20 patients with OHT with clinical indications for therapeutic IOP reduction were prospectively enrolled. IOP reduction was achieved by medical, laser, or surgical therapy. All patients had IOP reductions more than 20% and a minimum of 4 weeks follow-up. Blood flow measurements were performed by SLDF analysis software (version 3.3) using Heidelberg Retina Flowmeter images. Statistical evaluations were performed on both groups using a two-tailed distribution paired t test. Twenty patients with OAG had a mean IOP reduction of 37% after treatment. In these patients, mean (+/- standard deviation) rim blood flow increased by 67% (from 158 +/- 79 arbitrary units to 264 +/- 127 arbitrary units, P = 0.001), whereas mean temporal peripapillary retinal flow decreased by 7.4% (P = 0.24), and mean nasal peripapillary retinal flow increased by 0.3% (P = 0.96). Twenty OHT patients had a mean IOP reduction of 33% after treatment. In contrast to the OAG group, neither the mean rim blood flow (7.5% increase from 277 +/- 158 arbitrary units to 298 +/- 140 arbitrary units, P = 0.41) nor the mean temporal (P = 0.35) or nasal (P = 0.88) peripapillary retinal flow changed significantly. For a similar percentage of IOP reduction, OAG patients had a statistically significant improvement of blood flow in the neuroretinal rim of the ONH, whereas OHT patients did not demonstrate such a change. Peripapillary retinal blood flow, expected to be affected less in glaucoma, remained stable in both groups. In addition to indicating a response to therapy in OAG patients, the reported changes in rim perfusion suggest that ONH autoregulation may be defective in OAG while intact in OHT.