Clinical implications of the erroneous use of the Verhoeff Stereopter: a case report

The Verhoeff Stereopter test is currently used by some branches of the military to evaluate depth perception for career placement. A 22-year-old male presented for consultation after failing the Verhoeff stereopter test during an examination for Marine flight training school.

A complete vision examination was conducted. Stereopsis was evaluated using the Verhoeff Stereopter, Randot Stereotest and the Multi-stereo test.

A complete visual analysis revealed a mild refractive error, no ocular pathology, and normal binocularity. Stereopsis testing with the Verhoeff stereopter, Randot stereotest, and Multi-Stereo tests were normal. Subsequent investigation revealed that the original military tester did not follow proper testing protocol. When the erroneous testing condition was analyzed, we found that the stimulus horizontal disparity was eliminated. This lack of horizontal disparity makes it impossible to pass the test. We confirmed our findings by presenting the correct testing conditions and the erroneous testing conditions to five subjects with normal stereopsis. All subjects passed the Verhoeff test under standard protocols but failed under the erroneous condition. The critical factor that causes the elimination of horizontal disparity is identified.

Although this instrument is not popular among vision care practitioners, it is being utilized by various organizations. An understanding of the theoretical basis for the instrument would therefore be beneficial.