. Refraction and how to refract : including sections on optics, retinoscopy, the fitting of spectacles and eye-glasses, Fu;. 136.—TIk; Authors Schematic Eye for Stu<lyinp; Ki-tiiK)scoi)y. fined as tiio method of estimatini; the refraction of an e)-cby reflecting into it rays of lii^ht Axiin a plane or concave 154 RETINOSCOPV. 155 mirror, and observing the movement which the retinalillumination makes by rotating the mirror. Suggestion.—Before attempting to practise retinoscopyupon the human eye, the beginner is advised to study themethod upon one of the many schematic eyes to be foundi
. Refraction and how to refract : including sections on optics, retinoscopy, the fitting of spectacles and eye-glasses, Fu;. 136.—TIk; Authors Schematic Eye for Stu<lyinp; Ki-tiiK)scoi)y. fined as tiio method of estimatini; the refraction of an e)-cby reflecting into it rays of lii^ht Axiin a plane or concave 154 RETINOSCOPV. 155 mirror, and observing the movement which the retinalillumination makes by rotating the mirror. Suggestion.—Before attempting to practise retinoscopyupon the human eye, the beginner is advised to study themethod upon one of the many schematic eyes to be foundin the market. The principle of retinoscopy is the finding of the pointof reversal, or myopic far point; and when an eye is emme-tropic or hyperopic, it must be given a myopic far point bymeans of a convex sphere. (Fig. I37-) I Advantages of Retinoscopy.— 1. The character of the refraction is quickly diagnosed. 2. No expensive apparatus is necessarily required. 3. The refraction is estimated without the verbal assist-ance of the patient. 4. The correction is quickly obtained. 5. The value of retinoscopy can never be overestimatedin the young, in the feeble-minded, the illiterate ; in casesof nystagmus, amblyopia, and aphakia. Axiom.—With an eye otherwise ncirmal except for itsoptic error, and being under the influence of a reliablecycloplegic, there is no more exact objective method ofobtaining its refraction than by retinoscop)-. 156 REFRACTION AND HOW TO REFRACT. The surgeon should wear any necessary correctingglasses and have a vision of more than -— ; otherwise hecan never get satisfaction from this method. The surgeonshould keep his eyes wide open and not hesitate to use hisaccommodation, as it does not have any effect on the result,as in estimating the refraction with the ophthalmoscope. KALEVIMA
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