Ali S Hafez

Evaluation of Optic Nerve Head and Peripapillary Retinal Blood Flow in Glaucoma Patients, Ocular Hypertensives, and Normal Subjects

PURPOSE To compare optic nerve head (ONH) and peripapillary retinal blood flow in subjects with open-angle glaucoma (OAG), ocular hypertension (OHT), and normal eyes (NOR) using full-field perfusion analysis of scanning laser Doppler flowmetry (SLDF) images. DESIGN Prospective, nonrandomized clinical trial. METHODS Twenty uncontrolled OAG patients, 20 uncontrolled OHT patients, and 20 normal volunteers were prospectively enrolled. Mean ONH and peripapillary retinal blood flow measurements were performed by SLDF version 3.3 using five Heidelberg Retina Flowmeter (Heidelberg Engineering, Heidelberg, Germany) images. Statistical evaluations were performed on the three study groups using one-way analysis of variance. Flow values of the neuroretinal rim of the ONH, nasal peripapillary retina, and temporal peripapillary retina were then correlated with the clinical parameters of age, cup/disk (C/D) ratio, intraocular pressure (IOP), visual field mean defect, maximum-recorded IOP, and ocular perfusion pressure. Neuroretinal rim blood flow in the OAG group was 158 +/- 79 arbitrary units (au), whereas in the OHT group it was 277 +/- 158 au, and in the NOR group it was 272 +/- 93 au. Differences were statistically significant between the OAG group and each of the other groups (P =.001) but not between OHT and NOR groups (P =.91). Peripapillary retinal flow values showed no statistically significant differences between groups (P =.76 nasal and 0.93 temporal). RESULTS Neuroretinal rim flow values showed a significant inverse correlation with C/D ratio (P =.001). Mean neuroretinal rim blood flow was significantly higher (350 +/- 184 au) in the 10 OHT patients with C/D ratios < 0.4 when compared with the 10 OHT patients with larger C/D ratios (203 +/- 79 au) (P =.039). Conversely, peripapillary retinal blood flow showed no significant correlation with any clinical parameter. CONCLUSION Open-angle glaucoma patients had significantly lower blood flow in the ONH compared with OHT patients and normal volunteers. No significant differences in ONH blood flow were found between ocular hypertensives and normal volunteers. For peripapillary retinal blood flow, no significant difference was seen between any groups. Neuroretinal rim blood flow was significantly inversely correlated to increased C/D ratio. Ocular hypertensives with larger C/D ratios demonstrated significantly lower rim blood flow compared with those with smaller C/D ratios, suggesting that rim perfusion might be reduced in high-risk ocular hypertensives before the manifestation of visual field defects.

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

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.

Correlation between finger blood flow and changes in optic nerve head blood flow following therapeutic intraocular pressure reduction.

Purpose:To correlate finger blood flow and changes in optic nerve head (ONH) blood flow following therapeutic intraocular pressure (IOP) reduction in open-angle glaucoma (OAG) and ocular hypertension (OHT). Methods:Seventeen open-angle glaucoma patients and nineteen ocular hypertension patients underwent therapeutic IOP reduction followed by a minimum of 4 weeks of follow-up. Optic nerve head blood flow measurements were obtained by scanning laser Doppler flowmetry using full-field perfusion image analysis. Finger blood flow was measured using the Transonic laser Doppler Flowmeter. Finger blood flow was measured at baseline, after immersion in warm water (40°C) for 2 minutes (Flow Max), and after immersion in cold water (4°C) for 10 seconds (Flow Min). Patients were identified as vasospastic if their Flow Max/Flow Min >7. Statistical comparisons were performed using two-tailed distribution paired T-test and Pearsons correlation factor. Results:For similar mean percentage intraocular pressure reduction, vasospastic patients had greater improvements in rim blood flow than did non-vasospastic patients [+35% versus +13%] (P= 0.01). While there was no difference in rim blood flow changes in the vasospastic versus the non-vasospastic OAG group, the vasospastic ocular hypertension group showed 18% increase in rim blood flow whereas the non-vasospastic ocular hypertension group showed an 8% decrease. A significant negative correlation was also found in the open-angle glaucoma group between rim blood flow change and Flow Max (−0.681, P= 0.003). In contrast, no such correlation was found in the ocular hypertension group (+0.144, P= 0.556). Conclusion:OAG patients had a significant negative correlation between changes in rim blood flow and maximum finger Doppler flow. Among ocular hypertension patients, increased rim blood flow was only found in the vasospastic group, though this increase was not statistically significant. These results suggest that open-angle glaucoma and ocular hypertension patients with the most severe vasospastic disease may show the greatest improvements in rim blood flow after sustained intraocular pressure reduction.

Reproducibility of Retinal and Optic Nerve Head Perfusion Measurements Using Scanning Laser Doppler Flowmetry

BACKGROUND AND OBJECTIVE To evaluate the reproducibility of full-field perfusion analysis using scanning laser Doppler flowmetry (SLDF) for perfusion measurements of the neuroretinal rim of the optic nerve head and the peripapillary retina in patients with open-angle glaucoma or ocular hypertension, and in normal subjects. PATIENTS AND METHODS SLDF perfusion measurements of the neuroretinal rim and the peripapillary retina were performed on 20 patients with open-angle glaucoma or ocular hypertension (group G) and 20 normal volunteers (group N). Each subject underwent two independent sessions, 30 minutes apart, each involving 5 high quality images. Intrasession and intersession reproducibility coefficients for flow, volume, and velocity were calculated for a single image and for means of 3 and 5 images using analysis of variance models. flow, the intrasession coefficient of reliability was 0.99 each for the rim, nasal retina, and temporal retina in group G and 0.93, 0.93, and 0.95, respectively, in group N. The intersession coefficient of reliability for flow was 0.99 for the rim, 0.95 for the nasal retina, and 0.87 for the temporal retina in group G and 0.87, 0.82, and 0.80, respectively, in group N. Compared with single image analysis, intrasession and intersession reproducibility were generally better when a mean of 3 images and substantially better when a mean of 5 images was used. CONCLUSION SLDF full-field perfusion analysis is markedly more reproducible than the original software using 10 x 10 pixel windows. Obtaining mean values for at least 3 images improves the intrasession and intersession reproducibility of this technique.