Assessment of adult stereopsis using the Lang 1 Stereotest: A pilot study

Background and Purpose: To assess the use of the Lang 1 Stereotest as a vision-screening test for adults, for which little is known or reported. Method: The Lang 1 Stereotest was administered to 292 consecutive participants of the Visual Impairment Project (VIP) five year followup study, which is a population based study of eye disease in Melbourne, Australia. 56.9% were female. The mean age was 59.4 years, range 44-90 years. A "positive" stereoscopic response was recorded where the stereoscopic target image was correctly named; a "partial positive" response where depth was appreciated but the shape could not be named; and a "negative" response where there was no appreciation of a stereo effect. The responses were further categorized so that the test was either "passed" or "failed". A "pass" score was 3/3 positive responses; 3/3 partial positive responses or 2/3 positive and/or partial positive responses where the negative response was at the 550" of arc stereoacuity level. "Failure" was 3/3 negative responses and 2/3 negative responses where the positive or partial positive response as at the 1200" level. Results: Of the 292 participants tested, 19 (6.5%) participants "failed" the test. In addition to strabismus and anisometropia, failure was associated significantly (p<0.001) with reduced distance visual acuity (<6/12) irrespective of the ocular morbidity. Conclusion: The Lang 1 Stereotest correctly identified people with vision defects associated with reduced stereopsis. This suggests the Lang 1 Stereotest is an appropriate for the vision screening of adults as it is for children.