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Multicenter Study
. 2009 Jan;127(1):59-65.
doi: 10.1001/archophthalmol.2008.548.

Interobserver reliability of the prism and alternate cover test in children with esotropia

Pediatric Eye Disease Investigator Group
Collaborators
Multicenter Study

Interobserver reliability of the prism and alternate cover test in children with esotropia

Pediatric Eye Disease Investigator Group. Arch Ophthalmol. 2009 Jan.

Abstract

Objective: To determine 95% limits of agreement on a measurement and on a difference between 2 measurements for the prism and alternate cover test (PACT) at distance and at near fixation.

Methods: In a test-retest reliability study, 143 children aged 60 months or younger with esotropia were examined by 2 masked examiners on 1 or 2 occasions yielding 199 test-retest pairs for PACT at distance fixation and 239 test-retest pairs for PACT at near fixation.

Results: For angles greater than 20 prism diopters (PD), the 95% limits of agreement on a measurement and on a difference between 2 measurements were +/-7.3 PD and +/-10.4 PD, respectively, for PACT at distance and +/-8.3 PD and +/-11.7 PD, respectively, for PACT at near. For angles of 10 to 20 PD, the 95% limits of agreement on a measurement and on a difference between 2 measurements were +/-4.1 PD and +/-5.8 PD, respectively, for PACT at distance and +/-3.3 PD and +/-4.7 PD, respectively, for PACT at near.

Conclusion: In childhood esotropia, differences of 12 PD or more for angles greater than 20 PD and differences of 6 PD or more for angles between 10 PD and 20 PD are likely to indicate real change. Smaller differences could be real change but could also be due to measurement error.

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Figures

Figure 1
Figure 1
Bland Altman Plot of Test-Retest Difference vs. Average of Test and Retest Measurements for Prism and Alternate Cover (PACT) at Distance Fixation (a) and at Near Fixation (b). The solid horizontal line indicates no difference between the test and retest.
Figure 1
Figure 1
Bland Altman Plot of Test-Retest Difference vs. Average of Test and Retest Measurements for Prism and Alternate Cover (PACT) at Distance Fixation (a) and at Near Fixation (b). The solid horizontal line indicates no difference between the test and retest.
Figure 2
Figure 2
Plot of Test-Retest Difference vs. Age in Months for PACT Measurements at Distance Fixation (a) and at Near Fixation (b). The solid horizontal line indicates no difference between test and retest.
Figure 2
Figure 2
Plot of Test-Retest Difference vs. Age in Months for PACT Measurements at Distance Fixation (a) and at Near Fixation (b). The solid horizontal line indicates no difference between test and retest.
See this image and copyright information in PMC

References

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