A Badal optical stimulator for the Canon AutoRef R-1 optometer

The Canon AutoRef R-1 optometer is currently in use by several investigators in studies of accommodative response and open loop accommodation. It has the capability for frequent (1.4 s cycle time in "single shot" mode) objective measures of the refractive state of the eye and, because it uses near infrared radiation, it provides no stimulus to accommodation. In this paper we describe a compact device which can be mounted on the R-1 optometer, coaxial with the measurement optics of the optometer, to provide controlled optical vergence, i.e., accommodative stimulus, from +10.0 to -20.0 D while maintaining a constant visual angle.