RETINOSCOPE
\ɹˈɛtɪnˌɒskə͡ʊp], \ɹˈɛtɪnˌɒskəʊp], \ɹ_ˈɛ_t_ɪ_n_ˌɒ_s_k_əʊ_p]\
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An instrument consisting of a plane or concave mirror, with a peep-hole through the middle for throwing a light on the fundus of the eye. By observing the movement of the light on the fundus, as the mirror is moved with or against the light, and by placing plus or minus lenses in front of the eye, so as to just reverse the movement of the light, the refractive condition of the eye may be determined. The instrument must be used at a definite distance from the other eye, usually a meter.
By Smith Ely Jelliffe
Word of the day
Snake's-head
- Guinea-hen flower; -- so called in England because its spotted petals resemble the scales of a snake's head.