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Comparison between laser scanning tomography and computerised image analysis of the optic disc
A Azuara-Blanco1, G L Spaeth, J Nicholl
1Department of Ophthalmology Queen's Medical Centre, University of Nottingham.
The British Journal of Ophthalmology
|June 12, 1999
Summary
Measurements of optic disc topography using a computerized image analyzer and a laser tomographic scanner showed significant differences in cup volume and rim area. Interchangeability is limited, impacting glaucoma assessment.
Area of Science:
- Ophthalmology
- Medical Imaging
- Glaucoma Diagnosis
Background:
- Accurate optic disc topography measurement is crucial for glaucoma diagnosis and monitoring.
- Computerized image analyzers and confocal laser tomographic scanners are commonly used for optic disc assessment.
Purpose of the Study:
- To evaluate the interchangeability of optic disc topography measurements between a computerized image analyzer (Topcon ImageNet - TI) and a confocal laser tomographic scanner (Heidelberg Retina Tomograph - HRT).
Main Methods:
- Simultaneous stereoscopic disc photographs and HRT examinations were performed on 28 glaucoma patients.
- Optic disc photographs were digitized and analyzed using the TI system.
- Cup volume (CV), rim area (RA), and cup area to disc area ratio (CA/DA) were compared between TI and HRT.
Main Results:
- Mean CV and RA values were significantly higher with TI compared to HRT (p < 0.01).
- Mean CA/DA values were similar between TI and HRT (p = 0.93).
- Correlation coefficients between the two methods ranged from 0.53 to 0.73.
Conclusions:
- Significant discrepancies exist in rim area and cup volume measurements between the computerized image analyzer and the laser scanning tomograph.
- The interchangeability of these specific topographic parameters is limited.
- Clinical application requires careful consideration of the device used for optic disc topography assessment.