Text-book of ophthalmology . Figs. 394 to 396.—Reflected Images on the Cornea as Seen by the Ophthalmometer. a whole is diminished or enlarged and so too is its reflected image on the cornea. Ifthe size of the object is constant and its distance from the eye that is being tested isalso constant, the size of the reflected image will vary only with the degree of the cor-neal curvature. Hence the latter can be computed if the size of the reflected imageis known. Helmholtz was the first to measure this precisely, using the method of du-plication of the reflected image. The apparatus designed to ef
Text-book of ophthalmology . Figs. 394 to 396.—Reflected Images on the Cornea as Seen by the Ophthalmometer. a whole is diminished or enlarged and so too is its reflected image on the cornea. Ifthe size of the object is constant and its distance from the eye that is being tested isalso constant, the size of the reflected image will vary only with the degree of the cor-neal curvature. Hence the latter can be computed if the size of the reflected imageis known. Helmholtz was the first to measure this precisely, using the method of du-plication of the reflected image. The apparatus designed to effect this is placed in thetelescope which passes through the center of the arc B, and shows the reflected imagein a magnified form In the ophthalmometer of J aval and Schiotz, which is now gener-ally used, the doubling of the image is accomplished by a prism of double-refractingIceland spar, and in the instrument made by Kagenaar by means of two glass prismswhose refracting angles meet in the center. Hence, if we look thro
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecteye, booksubjectophth
