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Test-retest reliability of the Arden Grating Test: inter-tester variability.
B C Reeves1, A R Hill, J E Ross
1Visual Science Unit, Radcliffe Infirmary, Oxford, UK.
Summary
The Arden Grating Test (AGT) shows significant unreliability due to inter-tester differences, leading to a high misclassification rate in vision screening. This limits its effectiveness for reliable patient assessment.
Area of Science:
- Ophthalmology
- Vision Science
- Clinical Measurement
Background:
- The Arden Grating Test (AGT) is used for assessing contrast sensitivity.
- Reliability is crucial for diagnostic tools in vision screening.
Purpose of the Study:
- To evaluate the test-retest reliability of the Arden Grating Test (AGT).
- To determine the contribution of intra-subject and inter-tester variability to AGT scores.
Main Methods:
- Twelve patients with diverse visual pathologies were tested twice by six different clinicians.
- Statistical analysis was performed to assess score variance.
Main Results:
- Inter-tester differences accounted for approximately 25% of the total variance in AGT scores.
- The 95% confidence limits were +/- 15 AGT units, representing a significant portion of the test's dynamic range.
Conclusions:
- The Arden Grating Test exhibits considerable unreliability, particularly due to variations between testers.
- This unreliability results in a high rate of misclassification (false positives/negatives), impacting its utility in primary vision screening.