Purpose: 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.
Design: Prospective, nonrandomized, self-controlled trial.
Participants: Twenty patients with OAG and 20 patients with OHT with clinical indications for therapeutic IOP reduction were prospectively enrolled.
Intervention: 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.
Main outcome measures: 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.
Results: 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.
Conclusions: 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.