ASTEROID stereotest v1.0: lower stereo thresholds using smaller, denser and faster dots.

PURPOSE

In 2019, we described ASTEROID, a new stereotest run on a 3D tablet computer which involves a four-alternative disparity detection task on a dynamic random-dot stereogram. Stereo thresholds measured with ASTEROID were well correlated with, but systematically higher than (by a factor of around 1.5), thresholds measured with previous laboratory stereotests or the Randot Preschool clinical stereotest. We speculated that this might be due to the relatively large, sparse dots used in ASTEROID v0.9. Here, we introduce and test the stereo thresholds and test-repeatability of the new ASTEROID v1.0, which uses precomputed images to allow stereograms made up of much smaller, denser dots.

METHODS

Stereo thresholds and test/retest repeatability were tested and compared between the old and new versions of ASTEROID (n = 75) and the Randot Circles (n = 31) stereotest, in healthy young adults.

RESULTS

Thresholds on ASTEROID v1.0 are lower (better) than on ASTEROID v0.9 by a factor of 1.4, and do not differ significantly from thresholds on the Randot Circles. Thresholds were roughly log-normally distributed with a mean of 1.54 log arcsec (35 arcsec) on ASTEROID v1.0 compared to 1.70 log arcsec (50 arcsec) on ASTEROID v0.9. The standard deviation between observers was the same for both versions, 0.32 log arcsec, corresponding to a factor of 2 above and below the mean. There was no difference between the versions in their test/retest repeatability, with 95% coefficient of repeatability = 0.46 log arcsec (a factor of 2.9 or 1.5 octaves) and a Pearson correlation of 0.8 (comparable to other clinical stereotests).

CONCLUSION

The poorer stereo thresholds previously reported with ASTEROID v0.9 appear to have been due to the relatively large, coarse dots and low density used, rather than to some other aspect of the technology. Employing the small dots and high density used in ASTEROID v1.0, thresholds and test/retest repeatability are similar to other clinical stereotests.