Interobserver repeatability of heidelberg retinal flowmetry using pixel-by-pixel analysis.

PURPOSE: To determine the interobserver reproducibility of Heidelberg retinal flowmeter (HRF) blood flow measurements using independently selected study areas for pixel-by-pixel analysis. PATIENTS AND METHODS: Blood flow measurements were performed on 257 scans from 15 patients, 14 of whom had glaucoma or ocular hypertension. HRF was used to record capillary perfusion in a 2560x640 mum area of the supratemporal peripapillary region and pixel-by-pixel analysis was performed from an area adjacent to the optic disc with a minimum of 1600 pixels. Each observer independently selected the area for analysis. The percentage of pixels with <1 arbitrary unit of flow (no flow) and 10, 25, 50, 75, and 90th percentiles of flow values was calculated. Interobserver variability was assessed by estimating the intraclass correlation coefficient (ICC) and its 95% confidence interval. Bland-Altman plots of the difference between the 2 physicians versus the average of the 2 physicians for each outcome were created. RESULTS: ICC was 0.79 (range: 0.74 to 0.83) for mean flow values. For 0, 10, 25, 50, 75, and 90th percentiles of flow, the ICC was 0.67 (0.60 to 0.73), 0.74 (0.68 to 0.79), 0.82 (0.78 to 0.86), 0.85 (0.82 to 0.88), 0.85 (0.81 to 0.88), and 0.77 (0.72 to 0.82), respectively. Zero flow pixels had a nonsignificant mean difference between observers (P=0.542), whereas the remainder of the flow values demonstrated significant mean differences. CONCLUSIONS: This study demonstrates that independent observers can review high-quality HRF scans and may produce different absolute values while retaining strong consistency of agreement when independently selecting areas for analysis using the pixel-by-pixel method.

The effects of raloxifene hydrochloride on ocular hemodynamics and visual function.

OBJECTIVE: To assess the comprehensive effects of raloxifene hydrochloride on retinal, choroidal and retrobulbar hemodynamics and on visual function in post-menopausal women. DESIGN: Twenty-four post-menopausal women (age 55 +/- 3.8 years) were recruited for this cross-sectional study: 12 received placebo and 12 received raloxifene hydrochloride 60 mg once a day for 3 months. Baseline measurements of both groups included heart rate (HR), blood pressure (BP), visual acuity, contrast sensitivity and intraocular pressure (IOP) for both eyes. A comprehensive ocular blood flow (OBF) assessment was obtained for each patient in a randomly chosen study eye. Retinal blood flow data was obtained using confocal scanning laser Doppler flowmetry [Heidelberg Retinal Flowmeter (HRF)]. Color Doppler imaging (CDI) was used to assess retrobulbar hemodynamics in the ophthalmic, central retinal, short nasal and temporal posterior ciliary arteries. Baseline vision and hemodynamics in post-menopausal subjects were compared using paired Student's t tests, and the percentage change in baseline versus 3-month parameters was analyzed. RESULTS: There were no statistically significant differences between 3 months of raloxifene therapy and placebo in terms of age, HR, arterial or mean BP, visual acuity, contrast sensitivity, IOP or retinal or retrobulbar blood flow. CONCLUSION: Raloxifene therapy at 60 mg/day had no clinically significant impact on BP, IOP or OBF in post-menopausal women.

Measuring and interpreting ocular blood flow and metabolism in glaucoma.

There is a growing body of evidence suggesting that vascular dysfunction is related to several prominent ophthalmic diseases, including glaucoma. The vast majority of studies providing data on ocular circulation and disease pathophysiology use a relatively small number of complicated ocular blood flow imaging techniques. Although these imaging technologies are not commonly used in clinical settings, understanding the medical literature characterizing ocular blood flow requires familiarity with their methodology and function. This review highlights the imaging technologies most commonly used to investigate ocular blood flow, including color Doppler imaging, confocal scanning laser ophthalmoscopic angiography with fluorescein and indocyanine green dye, Canon laser blood flowmetry, scanning laser Doppler flowmetry, and retinal photographic oximetry. Each imaging technique's ability to define vascular function and reveal pathology is discussed as are limitations inherent to each technology. The ultimate goal of this review is to provide the physician with a clinically relevant foundation for differentiating the various ocular blood flow outcome measures often presented in the literature and determine how they are related to ocular health and disease.