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Color dissociation artifacts in double Maddox rod cyclodeviation testing
K Simons1, K Arnoldi, M H Brown
1Wilmer Ophthalmological Institute, Johns Hopkins Hospital, Baltimore, MD 21287-9009.
Ophthalmology
|December 1, 1994
Summary
The standard double Maddox rod test may inaccurately measure cyclodeviation due to its two-color format. Using same-color Maddox rods offers a more reliable method for assessing torsion in patients with superior oblique paresis.
Area of Science:
- Ophthalmology
- Neuro-ophthalmology
- Strabismus
Background:
- The double Maddox rod test is commonly used to measure cyclodeviation, particularly in patients with superior oblique muscle paresis.
- Discrepancies with other torsion measures and paradoxical findings suggest the test's two-color format may introduce measurement artifacts.
Purpose of the Study:
- To investigate potential artifacts in the traditional double Maddox rod test.
- To evaluate an alternative same-color Maddox rod testing method for cyclodeviation measurement.
Main Methods:
- Forty patients with superior oblique paresis underwent repeated double Maddox rod testing, with color reversal of rods.
- Eighteen patients were further tested using same-color Maddox rods (red or clear) before both eyes.
Main Results:
- 83% of patients localized cyclodeviation to the eye with the red Maddox rod in the standard test, with perceived torsion laterality changing upon rod reversal.
- 94% of patients correctly localized extorsion to the paretic eye when using same-color Maddox rods.
- Luminance transmission and spatial frequency differences between red and clear rods likely cause the artifact.
Conclusions:
- The traditional double Maddox rod test may yield artifactual measurements of cyclodeviation.
- An alternative test using same-color Maddox rods is proposed for improved accuracy.
- Testing in a dark room is recommended to mitigate visual environmental biases.