Validation of the revised LANG-STEREOTEST® I-II in a non-clinical adult sample

Summary Background The LANG-STEREOTEST® is a popular natural stereo test that has been used since the 1980s. It is characterized by its ease of use and can be performed with very young children. The sensitive random-dot stereo test is available in two versions and was revised in 2020 to improve print quality and to reduce monocular clues. The aim of this prospective study was to validate the revised versions in a non-clinical sample. Material and methods Testing was carried out in randomized order using either an original test version (LANG I‑O or LANG II-O) or a revised test version (LANG I‑R or LANG II-R), first monocularly and then binocularly. The other test version (original vs. revised) was then offered and participants had to indicate whether this test version was easier, equally difficult, or harder to recognize. An orthoptic screening (including visual acuity, autorefraction, cover test, and Titmus® Stereotest) concluded the examination. The entire test procedure was carried out under standardized conditions. Results In total, 56 eye-healthy adults were included. For both LANG-STEREOTEST® I and II and the respective revised versions, we found no relevant differences in recognizability when tested binocularly. When tested monocularly, we found similar results for LANG I‑O and I‑R (100% vs. 93% negative) and for LANG II‑O and II‑R (both 93% negative). Overall, 61.5% of the participants found that LANG I‑O was harder to recognize than LANG I‑R, and 56% found LANG II‑O was easier to recognize than LANG II‑R. Conclusion The revised versions are harmonized and differ less in brightness than the original versions I and II. In a non-clinical adult sample, LANG I‑O and LANG I‑R, as well as LANG II‑O and LANG II‑R, were valid. The results of the original LANG-STEREOTEST® versions I and II are comparable to the revised versions. In addition, monocular clues are reduced, at least for LANG II‑R.