When is retinoscopy used? Retinoscopy is used to determine refractive error in children, developmentally delayed adults, or in individuals whose behavior limits the ability to be cooperative with other refraction techniques. It is especially useful in very young children and infants.

What is the principle of retinoscopy?

The basic principle of retinoscopy is the Foucault test. In this test, a knife edge placed on the principal axis of an optical system (S) intercepts a bundle of rays coming out of (S). Depending on the position of the knife edge, various distributions of light and shadow can be observed on the anterior surface of (S).

What happens in a retinoscopy test?

The retinoscope aims light into your eye, and a reddish light reflects through your pupil and off your retina. We use the light to measure your focal length, or in other words, to measure the precise angle of refraction of light off your retina which tells us how well your eye is able to focus.