Retinoscopy is considered an "objective" method because the measurements are obtained without interaction or subjective information from the patient. The term retinoscopy literally means "an exam of the retina." By using retinoscopy, your eye doctor can determine the presence and degree of myopia, hyperopia, or emmetropia.
Retinoscopy is usually performed early in a typical eye examination. Your doctor or technician uses a retinoscope to project a streak of light into your pupil. A series of lenses are flashed in front of your eye. By looking through the retinoscope, your practitioner can study the light reflex of the pupil. Based on the movement and orientation of this retinal reflection, the refractive state of your eye is measured.
In most cases, retinoscopy is performed to give your eye doctor a starting point from which he or she can fine tune the refractive correction by using other testing methods. In skilled hands, however, retinoscopy can be extremely accurate.
Retinoscopy is especially useful when examining non-speaking patients or young children. It is also a good method for confirming a patient’s prescription if the patient has a difficult time giving the practitioner subjective feedback.
Corboy, John M, MD and David J Norath, COT. The Retinoscopy Book: An Introductory Manual for Eye Care Professionals. Pp 7-12. Slack, Inc, 2003.