Characteristics of a video-type pupillometer

In using a video-type pupillometer, the adjustment of the clipping level, the illumination of the target, the focus of the camera, and the viewing angle have been shown to affect the measurement. The focus of the camera and the viewing angle are the most important variables. The precision of this instrument can be as good as 0.01 mm. The accuracy of the instrument is good with regard to clinical standards; however, all measurements vary slightly from the known value. Interexaminer variation appears to be small.