ASTEROID stereotest v1.0: Lower stereo thresholds usingsmaller, denser and faster dots

Abstract

Purpose: In 2019, we described ASTEROID, a new stereotest run on a 3D tabletcomputer which involves a four-alternative disparity detection task on a dynamicrandom-dot stereogram. Stereo thresholds measured with ASTEROID were wellcorrelated with, but systematically higher than (by a factor of around 1.5), thresh-olds measured with previous laboratory stereotests or the Randot Preschool clini-cal stereotest. We speculated that this might be due to the relatively large, sparsedots used in ASTEROID v0.9. Here, we introduce and test the stereo thresholdsand test-repeatability of the new ASTEROID v1.0, which uses precomputedimages to allow stereograms made up of much smaller, denser dots.Methods: Stereo thresholds and test/retest repeatability were tested and comparedbetween 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 ASTEROIDv0.9 by a factor of 1.4, and do not differ significantly from thresholds on the Ran-dot Circles. Thresholds were roughly log-normally distributed with a mean of1.54 log 10 arcsec (35 arcsec) on ASTEROID v1.0 compared to 1.70 log 10 arcsec(50 arcsec) on ASTEROID v0.9. The standard deviation between observers wasthe same for both versions, 0.32 log 10 arcsec, corresponding to a factor of 2 aboveand below the mean. There was no difference between the versions in their test/retest repeatability, with 95% coefficient of repeatability = 0.46 log10 arcsec (afactor of 2.9 or 1.5 octaves) and a Pearson correlation of 0.8 (comparable to otherclinical stereotests).Conclusion: The poorer stereo thresholds previously reported with ASTEROIDv0.9 appear to have been due to the relatively large, coarse dots and low densityused, rather than to some other aspect of the technology. Employing the smalldots and high density used in ASTEROID v1.0, thresholds and test/retest repeata-bility are similar to other clinical stereotests.