Head-Mounted Video Camera System in Testing Multihandicapped Children with Low Vision

Abstract

Vision testing with multihandicapped children is more difficult than with normally developed children: the child's ability to concentrate in the test situation is often markedly reduced, or the child is not capable of communicating with the examiner in the normal way owing to deficiencies in motor skills, hearing, or speech. Often observation of the eyes and face is difficult because of bent-down sitting position caused by poor control of head and neck. By recording the test situation on a video tape it is possible to analyse the child's reactions afterwards more accurately. Our video system consists of a miniature video camera attached to the head of the child with a small mirror in front of the camera to provide a picture of the eyes. Simultaneous recording of the eye movements and the fixation target is possible by adjusting the position of the mirror so that it covers the view of the camera only partially. With the aid of a second, conventional video camera, we get an overview picture of the test situation. This picture is combined with the image of the miniature camera on the child's head and recorded on a video tape. With our video system it is possible to see the eye movements even when the child's head is bent-down or the child is moving in the examination room. It also allows the use of full-field stimuli covering the eyes as in examination of the optokinetic nystagmus. The eye - hand coordination can also be monitored on the video tape.