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The repeatability of discrete and continuous anterior segment grading scales
1Centre for Contact Lens Research, School of Optometry, University of Waterloo, Ontario, Canada.
Summary
Three anterior segment clinical grading scales demonstrated high reliability for assessing ocular conditions. The continuous matching scale (CS) offered superior precision for grading bulbar redness and palpebral conjunctival roughness.
Area of Science:
- Ophthalmology
- Optometry
- Clinical Research
Background:
- Accurate grading of anterior segment ocular conditions is crucial for diagnosis and treatment.
- Existing clinical grading scales, including verbal descriptors scale (VDS), photographic matching scale (PS), and continuous matching scale (CS), vary in their repeatability.
Purpose of the Study:
- To evaluate and compare the test-retest repeatability of three anterior segment clinical grading scales: VDS, PS, and CS.
- To determine which scale offers the highest precision for grading specific ocular surface conditions.
Main Methods:
- Five optometrists independently graded 30 slides each of ocular staining, bulbar redness, and palpebral conjunctival roughness twice.
- VDS and PS utilized a five-point scale (0-4) with half grades; CS employed a 5-second video movie.
- Grading was performed with visual references on a computer screen, with at least a one-day interval between assessments.
Main Results:
- All three scales exhibited high test-retest reliability, with intraclass correlation coefficients, concordance correlation coefficients, and Pearson's r ranging from 0.95 to 0.99 (p < 0.001).
- Coefficients of repeatability for CS ranged from 0.31 to 0.49.
- PS generally showed better repeatability than VDS, with coefficients ranging from 0.37 to 0.49.
Conclusions:
- The verbal descriptors scale, photographic matching scale, and continuous matching scale are all reliable for grading anterior segment ocular conditions.
- The continuous matching scale demonstrated superior precision in grading bulbar redness and palpebral conjunctival roughness compared to the other scales.