retinoscope

An optical device used to illuminate a subject's retina during retinoscopy. [retino- + G. skopeo, to view]

- luminous r. a portable optical device providing either a circular or linear (streak) beam of light.

- reflecting r. a plane or concave mirror with a central perforation that allows the observer to see rays emerge from the subject's eye.

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ret·i·no·scope 'ret-ən-ə-.skōp n an apparatus used in retinoscopy

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n.

an instrument used to determine the power of spectacle lens required to correct errors of refraction of the eye. It is held in the hand and casts a beam of light into the subject's eye. The examiner looks along the beam and sees the reflection in the subject's pupil. By interpreting the way the reflection moves when he moves the instrument, and by altering this by lenses held in his other hand near the subject's eye, he is able to detect long- or short-sightedness or astigmatism and to determine its degree.

• retinoscopy n.

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ret·i·no·scope (retґĭ-no-skōp″) an instrument for performing retinoscopy; called also skiascope.