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Heidelberg retinal flowmetry: factors affecting blood flow measurement
L Kagemann1, A Harris, H S Chung
1Department of Ophthalmology, Indiana University School of Medicine, Indianapolis 46202, USA.
The British Journal of Ophthalmology
|June 5, 1998
Summary
Heidelberg retinal flowmeter (HRF) measurements are not affected by laser angle but are influenced by camera distance. For reliable blood flow data, use pixel-by-pixel analysis of the entire image.
Area of Science:
- Ophthalmology
- Medical Imaging
- Physiology
Background:
- The Heidelberg retinal flowmeter (HRF) is used to measure retinal and optic nerve head blood flow.
- Understanding factors affecting HRF measurements is crucial for accurate clinical assessment.
Purpose of the Study:
- To evaluate factors influencing Heidelberg retinal flowmeter (HRF) measurements of retinal and optic nerve head blood flow.
- To determine the impact of laser incidence angle and camera distance on HRF readings.
Main Methods:
- Assessed the effect of laser beam to fundus angle and camera distance on blood volume, velocity, and flow in normal volunteers.
- Studied intra- and intersession reproducibility of HRF measures.
- Analyzed hemodynamic data using pixel-by-pixel flow histograms of the entire image.
Main Results:
- HRF flow measures were independent of the laser beam to fundus angle of incidence.
- Increasing camera distance led to greater individual changes in flow measurements.
- Intersession reproducibility improved significantly when using flow histograms from the entire image.
Conclusions:
- HRF flow measurements are reliable regarding laser incidence angle but sensitive to camera distance.
- Pixel-by-pixel analysis of the entire image enhances intersession reproducibility for HRF measurements.