The Repeatability of Discrete and Continuous Anterior Segment Grading Scales

Purpose To investigate the repeatability of three anterior segment clinical grading scales: 1) verbal descriptors scale (VDS), 2) photographic matching scale (PS), and 3) continuous matching scale (CS). Methods Five optometrists graded 30 slides each of 3‐9‐o'clock staining, bulbar redness, and palpebral conjunctival roughness twice, separated by at least a day. VDS and PS were five‐point scales (0–4) with half grades permitted. The CS was a 5‐second, 240‐frame video movie generated using morphing software. PS and CS grading was done with references presented on a computer screen. Results Averaged across observers, the test‐retest intraclass correlation, correlation coefficient of concordance, and Pearson's r ranged from 0.95 to 0.99 (all p < 0.001). Coefficients of repeatability using CS to grade all three ocular conditions ranged between 0.31 and 0.49. The corresponding PS and VDS coefficients of repeatability ranged between 0.37 and 0.49; PS generally had better repeatability than VDS. Conclusions Each of the clinical grading scales was reliable. The coefficients of repeatability showed that bulbar redness and palpebral conjunctival roughness were graded with higher precision using CS.