Defining Real Change in Prism-Cover Test Measurements

Jonathan M Holmes, David A. Leske, George G. Hohberger

Research output: Contribution to journalArticle

31 Citations (Scopus)

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.

Original languageEnglish (US)
Pages (from-to)381-385
Number of pages5
JournalAmerican Journal of Ophthalmology
Volume145
Issue number2
DOIs
StatePublished - Feb 2008

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Strabismus
Abducens Nerve Diseases
Cohort Studies
Prospective Studies
Surgeons

ASJC Scopus subject areas

  • Ophthalmology

Cite this

Defining Real Change in Prism-Cover Test Measurements. / Holmes, Jonathan M; Leske, David A.; Hohberger, George G.

In: American Journal of Ophthalmology, Vol. 145, No. 2, 02.2008, p. 381-385.

Research output: Contribution to journalArticle

Holmes, Jonathan M ; Leske, David A. ; Hohberger, George G. / Defining Real Change in Prism-Cover Test Measurements. In: American Journal of Ophthalmology. 2008 ; Vol. 145, No. 2. pp. 381-385.
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