A comparison of stereopsis testing between red/green targets and polarized targets in children with normal binocular vision

Abstract

Background: Measurement of stereopsis is important in assessing a patient's binocular status. Several measurement methods are available, most commonly using polarized targets. Recently, less expensive red/green targets have become available. In this study, we compare polarized versus red/green methods, using random dot and contour targets.

Methods: Sixty children with no strabismus, amblyopia, or high refractive error and normal ocular health were recruited. Stereopsis measurements were taken using the red/green and polarized versions of the Random Dot Letter "E"/RDE Test, Random Dot Butterfly/Stereo Butterfly Test, Stereo Circles/Wirt Circles, Stereo Numbers, and Stereo Animals tests. Observed agreement was used to assess agreement between results. Wilcoxon signed-rank tests were used to compare an individual's response with both targets.

Results: There was greater than 95% agreement using any of the Random Dot-based tests and the Stereo Animals tests. However, agreement was less than 60% with the Stereo Numbers test and less than 35% with the Stereo Circles/Wirt Circles test.

Conclusion: The red/green versions of the Random Dot-based tests and the Stereo Animals test appear to be a cost-effective alternative to their polarized equivalents. Our data, however, show that the red/green versions tend to underestimate the level of stereopsis when using the Stereo Numbers and Stereo Circles/Wirt Circles tests compared to their polarized equivalents.