Test-retest variability of cyclodeviations measured using the double Maddox rod test

Area of Science:

• Ophthalmology
• Neuro-ophthalmology
• Strabismus assessment

Background:

• The double Maddox rod test is a common clinical tool for quantifying cyclodeviations.
• Monitoring changes in cyclodeviation is crucial for managing various ocular motility disorders.

Purpose of the Study:

• To determine the test-retest reliability of the double Maddox rod test.
• To establish a threshold for significant change in cyclodeviation measurements.

Main Methods:

• Retrospective analysis of 86 clinically stable patients.
• Double Maddox rod measurements were taken 5-175 days apart (median 69 days).
• Calculation of 95% limits of agreement to assess reliability and define real change.

Main Results:

• The calculated half-width of the 95% limits of agreement was 4.7 degrees.
• This indicates that a change of 5 degrees or more in cyclodeviation should be considered a real change.
• The initial measurements ranged from 6 degrees incyclodeviation to 15 degrees excyclodeviation.

Conclusions:

• A change of at least 5 degrees in cyclodeviation is recommended as the threshold for real change when using the double Maddox rod test.
• This threshold aids in distinguishing true progression or resolution from measurement variability.
• The findings support the clinical utility of the double Maddox rod test for monitoring cyclodeviations over time.