Retinoscopy is a technique to obtain an objective measurement of the refractive error of a patient's eyes.

While moving the streak or spot of light through the pupil across the retina, the examiner observes the relative movement of the reflex or manually places lenses over the eye (using a phoropter or trial frame and trial lenses) to "neutralize" the reflex.

It relies on Foucault knife-edge test, which states that the examiner should simulate optical infinity to obtain the correct refractive power.

Dynamic retinoscopy is performed when the patient has active accommodation from viewing a near target.

[4] Retinoscopy is particularly useful in prescribing corrective lenses for patients who are unable to undergo a subjective refraction that requires a judgement and response from the patient (such as children or those with severe intellectual disabilities or communication problems).