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Optic disc biomorphometry with the Heidelberg Retina Tomograph at different reference levels
Kyösti Vihanninjoki1, Reinhard O W Burk, Pait Teesalu
1Department of Ophthalmology, University of Oulu, Oulu, Finland.
Acta Ophthalmologica Scandinavica
|March 22, 2002
Summary
The flexible reference level (REFf) on the Heidelberg Retina Tomograph (HRT) provides the most reliable optic disc measurements for both healthy and glaucoma patients. This method offers superior accuracy compared to other reference levels, especially in advanced glaucoma cases.
Area of Science:
- Ophthalmology
- Medical Imaging
- Glaucoma Research
Background:
- The Heidelberg Retina Tomograph (HRT) is a key tool for optic disc imaging.
- Accurate stereometric measurements depend on the chosen reference plane level.
- Previous HRT software versions had varying reference level implementations.
Purpose of the Study:
- To evaluate the clinical advantages and disadvantages of four different reference levels for HRT measurements.
- To determine the most reliable reference level for optic disc topography.
- To compare measurement accuracy across different glaucoma severities.
Main Methods:
- Sixty-seven eyes (40 healthy, 27 glaucoma) were analyzed using HRT software versions 1.09 and 1.11.
- Four reference levels were tested: fixed offset (REFd), individual (REFi), papillo-macular (REFm), and flexible (REFf).
- Analysis of variance (ANOVA) was used to compare topographic parameters between reference levels.
Main Results:
- Reference levels yielded similar results in healthy eyes.
- Significant differences were observed with advanced glaucoma using the fixed offset (REFd) level.
- The flexible reference level (REFf) and papillo-macular reference level (REFm) showed consistent results across all groups.
- REFf, defined by the lowest point on the contour line, proved most stable and clinically useful.
Conclusions:
- The flexible reference level (REFf) is currently the most reliable and adequate for HRT measurements.
- REFf provides consistent and clinically relevant topographic data for both normal and glaucomatous eyes.
- This finding is crucial for accurate glaucoma diagnosis and monitoring.