[Induction of optokinetic nystagmus in infants and young children by a horizontally, diagonally or vertically moving striped pattern].

Horizontal optokinetic nystagmus (H-OKN) in infants is often described in contrast to diagonal (D-OKN) and vertical (V-OKN) nystagmus. No systematic investigation has been carried out to test the elicitability of D- and V-OKN in relation to the direction of the moving stimulus or the effect of stimulating the two eyes simultaneously or separately. We examinated the elicitability of H-, D- and V-OKN in more than 400 infants between birth and 5 years of age in two test situations: with both eyes open and with one eye covered. The stimulation device was a (hand-driven) drum of 12.2 cm diameter, on which a paper sheet with a pattern of black and white stripes (20 mm) kept in a horizontal, diagonal and vertical position, respectively. The distance to the infant's face was kept at ca. 25 cm. The occurrence of OKN was studied in all the six stimulation situations. Results demonstrated a clear developmental course in the monocular tests situation of the occurrence of OKN: at first only horizontal OKNs can be elicited, thereafter diagonal and finally vertical OKNs appeared. In general OKNs in all 6 testsituations are evident from the age of 3-24 months. However, in risico infants, deficits in at least one of the test situations were observed until the age of 5 years. Our results point towards a role of testing OKN as a screening method for detecting visual or brain dysfunction.