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.

Keywords: Stereopsis, Depth perception, Anaglyph testing, Polarization