Fast and reliable stereopsis measurement at multiple distances with iPad
This provides a new tool for eye care professionals to quickly screen stereopsis, but it is incremental as it adapts existing methods to a mobile platform.
The researchers developed an iPad app for screening stereopsis at multiple distances and found it to be fast and reliable, with better reproducibility (k = 0.801) than the TNO test (k = 0.715) at near distance, though it showed poor agreement with the Howard Dolman test at far distance due to iPad resolution limits.
Purpose: To present a new fast and reliable application for iPad (ST) for screening stereopsis at multiple distances. Methods: A new iPad application (app) based on a random dot stereogram was designed for screening stereopsis at multiple distances. Sixty-five subjects with no ocular diseases and wearing their habitual correction were tested at two different distances: 3 m and at 0.4 m. Results were compared with other commercial tests: TNO (at near) and Howard Dolman (at distance) Subjects were cited one week later in order to repeat the same procedures for assessing reproducibility of the tests. Results: Stereopsis at near was better with ST (40 arcsec) than with TNO (60 arcsec), but not significantly (p = 0.36). The agreement was good (k = 0.604) and the reproducibility was better with ST (k = 0.801) than with TNO (k = 0.715), in fact median difference between days was significant only with TNO (p = 0.02). On the other hand, poor agreement was obtained between HD and ST at far distance (k=0.04), obtaining significant differences in medians (p = 0.001) and poorer reliability with HD (k = 0.374) than with ST (k = 0.502). Conclusions: Screening stereopsis at near with a new iPad app demonstrated to be a fast and realiable. Results were in a good agreement with conventional tests as TNO, but it could not be compared at far vision with HD due to the limited resolution of the iPad.