[Expert system for automatic, subjective determination of refraction]

An automatic system for determining a patient's subjective refraction for the fitting of glasses or contact lenses, is described. The system works without any intervention on the part of the ophthalmologist or optometrist. Directions are provided and questions asked of the patient via a loudspeaker or headphones with the aid of a computer. This computer also controls the positioning of different lenses before the patient's eyes using a phoropter, and the projection of the chart figures for visual acuity testing. The patient responds via a dedicated graphic tactile answering unit. The principles involved are described, and the experience so far gained with the method discussed.