Humphrey 597 Auto Refractor The Humphrey 597 provides refinement of sphere, cylinder and axis for true optimization. In addition, near vision, glare, complete subjective testing and special targets for children and patients with reading difficulties allow the practitioner to test the widest range of patients. Precise keratometric readings are performed quickly and easily during the refraction process. This unit is available as a preowned item. We guaranty the good operating conditions.