skiascope
/ˈskaɪəˌskoʊp/
noun
- An instrument used to measure the refractive power of the eye by observing the movement of light and shadows on the retina; also called a retinoscope.
- With the skiascope, the doctor could quickly check for nearsightedness.
- Modern skiascopes are handheld and use a bright LED light source.
- The optometrist used a skiascope to determine the child's eyeglass prescription.