photorefraction


photorefraction 

A family of photographic techniques that provide a rapid, objective method of measuring the refractive error and accommodative response of the eye. Light emitted from a small flash source placed close to the camera lens is reflected from the eye and returned to the camera. Three methods have been developed: orthogonal, isotropic and eccentric (also called photoretinoscopy). The optical design of each method results in a specific photographic pattern, which varies with the degree to which the eye is defocused with respect to the plane of the camera. Photorefractive methods are not as accurate as retinoscopy but as they are entirely objective, much quicker and do not require prolonged fixation on the part of the patient, they are highly suited for testing infants and young children. See optometer; refractive error; retinoscope.