[A new haploscopic test device excludes blinking induced monocular perception].

BACKGROUND

Haploscopic tests like the pola-test are used to detect functional loss of vision, aggravation or simulation. They aim at confusing the tested person about the relation of disparate monocular visual perceptions to the right and left eyes. The haploscopic confusion can be overcome easily by single sided blinking. Other investigators have faced this problem by presenting optotypes very briefly, thus excluding blinking artefacts. We introduce a new device for shutting off the optotype projection whenever blinking occurs.

MATERIALS AND METHODS

A newly developed mechanism slightly presses small lever-switches onto each upper eyelid of a test person while performing the pola test. The levers move up and down following eyelid movements. Lid closure triggers a shut off of the optotype projector. The device was tested on 30 persons.

RESULTS

The device worked properly on 59/60 eyes. 24/30 persons did not realize the haploscopic confusion at the beginning, but 6/30 did right away. 18/30 would not realize the haploscopic confusion even after some experience.

CONCLUSIONS

The new device worked on nearly all patients and effectively kept most of them from overcoming the haploscopic confusion. It is a useful upgrading for haploscopic tests, making them applicable even in repeated examinations. It should be helpful to detect single-sided functional loss of vision.