Jonathan M Holmes1, David A Leske, George G Hohberger. 1. Department of Ophthalmology, Mayo Clinic, College of Medicine, 200 First Street SW, Rochester, MN 55905, USA. holmes.jonathan@mayo.edu
Abstract
PURPOSE: To describe the interobserver test-retest variability of both simultaneous prism and cover testing (SPCT) and alternate prism and cover testing (APCT) in horizontal deviations, and to calculate 95% limits of agreement that might be used to define real change. DESIGN: Prospective cohort study. METHODS: Twenty-three patients with sixth nerve palsy and three controls were independently examined by two experienced strabismus surgeons. SPCT and APCT were performed at distance and near fixation. Test-retest variability and agreement between tests were evaluated using Bland-Altman plots and 95% limits of agreement were calculated. RESULTS: For SPCT, the 95% limits of agreement half-widths were 6.3 prism diopters (pd) at distance fixation and 6.9 pd at near. For APCT, the 95% limits of agreement half-widths were 10.2 pd at distance and 9.2 pd at near. CONCLUSIONS: Based on 95% limits of agreement half-widths between two examiners, a change in strabismus measurements of less than 10 pd may be attributable to test-retest variability. Changes of 10 pd or more are likely to represent real change and might be used as the threshold for management decisions.
PURPOSE: To describe the interobserver test-retest variability of both simultaneous prism and cover testing (SPCT) and alternate prism and cover testing (APCT) in horizontal deviations, and to calculate 95% limits of agreement that might be used to define real change. DESIGN: Prospective cohort study. METHODS: Twenty-three patients with sixth nerve palsy and three controls were independently examined by two experienced strabismus surgeons. SPCT and APCT were performed at distance and near fixation. Test-retest variability and agreement between tests were evaluated using Bland-Altman plots and 95% limits of agreement were calculated. RESULTS: For SPCT, the 95% limits of agreement half-widths were 6.3 prism diopters (pd) at distance fixation and 6.9 pd at near. For APCT, the 95% limits of agreement half-widths were 10.2 pd at distance and 9.2 pd at near. CONCLUSIONS: Based on 95% limits of agreement half-widths between two examiners, a change in strabismus measurements of less than 10 pd may be attributable to test-retest variability. Changes of 10 pd or more are likely to represent real change and might be used as the threshold for management decisions.
Authors: Juan Antonio Portela-Camino; Santiago Martín-González; Javier Ruiz-Alcocer; Igor Illarramendi-Mendicute; Rafaela Garrido-Mercado Journal: Clin Optom (Auckl) Date: 2021-07-05