Reliability of a portable head-mounted eye tracking instrument for schizophrenia research.

Smooth pursuit eye movement (SPEM) abnormalities are some of the most consistently observed neurophysiological deficits associated with genetic risk for schizophrenia. SPEM has been traditionally assessed by infrared or video oculography using laboratory-based fixed-display systems. With growing interest in using SPEM measures to define phenotypes in large-scale genetic studies, there is a need for measurement instruments that can be used in the field. Here we test the reliability of a portable, head-mounted display (HMD) eye movement recording system and compare it with a fixed-display system. We observed comparable, modest calibration changes across trials between the two systems. The between-methods reliability for the most often used measure of pursuit performance, maintenance pursuit gain, was high (ICC = 0.96). This result suggests that the portable device is comparable with a lab-based system, which makes possible the collection of eye movement data in community-based and multicenter familial studies of schizophrenia.