Accurate Adult Stereopsis Assessment Requires Multiple Stereoacuity Measurements

Obtaining multiple stereoacuity measurements over the course of several days may be optimal for clinically assessing adult stereopsis, according to research published in Ophthalmic and Physiological Optics. 

Researchers conducted a study of adults with normal binocular vision (n=17) between the ages of 18 and 50 years. Patients underwent stereoacuity measurements using the Randot and TNO stereotests on 5 separate occasions across a 6-week period. Crossed and uncrossed stimuli were used to separately assess stereoacuity in both disparity directions. A subset of the participants (n=11) completed an additional 5 visits over a second 6-week period. The team determined threshold stereoacuity by the lowest disparity level at which the participants could correctly identify both the position and disparity direction (crossed or uncrossed) of the stimulus.  

The report shows that stereoacuity for both crossed and uncrossed stimuli improved significantly over the course of the first 5 visits (F_1,21 =4.24; P =.05). The influence of disparity direction on stereoacuity was not significant (F₁ = 0.02; P =.91), but there was a significant interaction between disparity direction and stereotest (F₁ =7.92, P =.01). 

“Our data suggest that differences between crossed and uncrossed stereoacuity may be present on initial testing but reduce or disappear after a period of repeated measurements,” according to the researchers. “To be assured that any discrepancy between crossed and uncrossed stereoacuity is genuine, multiple measurements should be taken to consider any improvement that can be made with practice.”

Study limitations include a small sample size and the disparity range of the Randot stereotest.