Deficient stereopsis in the normal population revisited: why current clinical stereo tests may not be adequate

Abstract

9Significance statement: Applied applications for occupational screening, clinical tests should 3 0 assess sensitivity to the sign as well as the magnitude of disparity. 1Purpose: To determine why the high incidence of stereo anomaly found using laboratory tests 3 2 with polarity-based increment judgements (i.e., depth sign) is not reflected in clinical 3 3 measurements that involve single-polarity incremental judgements (i.e., depth magnitude). 4Methods: An iPod-based measurement that involved the detection of an oriented shape defined 3 5 by a single polarity-depth increment within a random dot display was used. A staircase 3 6 procedure was used to gather sufficient trials to derive a meaningful measure of variance for the 3 7 measurement of stereopsis over a large disparity range. Forty-five adults with normal binocular 3 8 vision (20 -65 years old) and normal or corrected-to-normal (0 logMAR or better) monocular 3 9vision participated in this study. 0Results: Observers' stereo acuities ranged between 10 and 100 arc seconds, and were 4 1 normally distributed on a log scale (p = 0.90, 2-tailed Shapiro-Wilk test). The present results 4 2 using a single polarity depth increment task (i.e., depth magnitude) show a similar distribution to 4 3 those using a similar task using the Randot preschool stereo test on individuals between the 4 4 ages of 19-35 using either the 4-book test (n = 33) or the 3-book test (n = 40), but very different 4 5 results when the iPod test involved a polarity-based increment judgement (i.e., depth sign). 4 6 Conclusions: The present clinical stereo tests are based on magnitude judgements and are 4 7 unable to detect the high percentage of stereo anomalous individuals in the normal population 4 8 revealed using depth sign judgements.4 9

Can Clinical Measures of Postoperative Binocular Function Predict the Long-Term Stability of Postoperative Alignment in Intermittent Exotropia?

“…However, our patients only had one assessment per follow-up. Another potential explanation might be that the clinical methods used here (e.g., Worth's 4-dot test for fusion; TNO for stereopsis) are designed to identify the degree of impairment rather than to measure individuals' ability [20,32]. Accordingly, the clinical methods are not as accurate as those lab-based methods.…”

Lässt sich anhand von klinischen Variablen der Binokularfunktion die langfristige Stabilität der postoperativen Augenstellung nach Korrektur einer intermittierenden Exotropie vorhersagen?

“…Eine weitere mögliche Erklärung könnte sein, dass die hier verwendeten klinischen Verfahren (z.B. 4-Lichter-Test nach Worth für die Fusion; TNO für das stereoskopische Sehen) eher das Ausmaß einer Störung als die Fähigkeit des Patienten messen [20, 32]. Entsprechend sind die klinischen Methoden weniger präzise als im Labor angewendete.…”

Stereo-anomaly is found more frequently in tasks that require discrimination between depths

“… 3 Although these two approaches to clinical stereo measurement are different in several ways, one possible explanation of this difference is particularly interesting: stereo deficits may be specific to tasks where the polarity of the depth must be discriminated. 9 , 10 These stereo-anomalies would not be found with tests such as the Randot, which rely simply on detecting shapes defined by disparity.…”