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Variability across the optic nerve head in scanning laser tomography.
J C H Tan1, D F Garway-Heath, R A Hitchings
1Moorfields Eye Hospital and Institute of Ophthalmology, London, UK.
The British Journal of Ophthalmology
|April 26, 2003
Summary
Scanning laser tomography of the optic nerve head shows rim area is reproducible. Variability in this measurement is influenced by operators, visits, and reference planes, which is crucial for glaucoma progression assessment.
Area of Science:
- Ophthalmology
- Medical Imaging
- Glaucoma Research
Background:
- Accurate measurement of optic nerve head (ONH) parameters is vital for diagnosing and monitoring glaucoma.
- Scanning laser tomography (SLT) is a common imaging technique, but understanding its measurement variability is essential for reliable clinical interpretation.
Purpose of the Study:
- To characterize the measurement variability of various parameters obtained through scanning laser tomography of the optic nerve head.
- To assess the reproducibility of ONH measurements under different testing conditions, including operator and day variations.
Main Methods:
- Heidelberg Retina Tomograph (HRT) imaging was performed on 21 normal and 21 glaucoma subjects.
- Test-retest reliability was evaluated using same-day and separate-day imaging sessions.
- Imaging was conducted by both the same and different operators to assess inter-observer variability.
Main Results:
- The rim area parameter demonstrated the highest reproducibility among all measured parameters.
- Measurement variability was most pronounced in the temporal region and increased significantly with different operators and testing days (p<0.05).
- Regional variability patterns differed between normal and glaucoma eyes, as well as between standard and 320 µm reference planes.
Conclusions:
- The rim area is a reproducible parameter and shows potential as a reliable marker for monitoring glaucoma progression.
- The observed patterns of variability, influenced by reference planes, disease status, operators, and testing intervals, must be considered when evaluating ONH changes over time.