File:The refraction of the eye; including a complete treatise on ophthalmometry; (1900) (14763693615).jpg

Identifier: refractionofeye00davi (find matches)
Title: The refraction of the eye; including a complete treatise on ophthalmometry;
Year: 1900 (1900s)
Authors: Davis, Achilles Edward, 1866- (from old catalog)
Subjects: Eye Eye
Publisher: New York, London, The Macmillan company
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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axis of the cylinder in the right eye varied 5° from thereading of the ophthalmometer; second, I converted the cross-cylinder in the left eye into a sphero-cylinder,—a minussphere with a plus cylinder, — and for three reasons : (a) tomake the cylinder correspond to the right eye ; (h) because,in this case, it is a lighter glass than the sphero-cylinder with aplus sphere and a minus cylinder; and (c) a cheaper glass. ILLUSTRATIVE CASES 189 And this brings me to speak, in a general way, in referenceto such cases as the present one, where there is a mixed astig-matism in one eye and simple or compound astigmatism in theother. In converting the cross-cylinders into sphero-cylinders,some regard must be had that the character (plus or minus) ofthe cylinder in the transposed glass correspond to the cylinderin the opposite eye. Because, as a rule, a plus cylinder on oneeye and a minus cylinder on the other do not work as wellas when both are positive or negative. This point should be 105
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Fig. 80. borne in mind, in converting cross-cylinders; and, unless by sodoing the weight of the glass is greatly increased, cylinders ofa like character should be given. Sometimes in such cases itis better to give the cross-cylinder in the mixed astigmatic eye.especially if the astigmatism is of large amount, rather thanconvert it into a sphero-cylinder, either with plus sphere andminus cylinder, or minus sphere and plus cylinder; and, byputting the different combinations in front of the eye for a fewmoments, the patient will often make the choice for himself. 190 THE REFRACTION OF THE EYE Case LXXV. Mixed astigmatism with tJie 7ide right eye;Hypermetropic astigmatism ivith the ride left eye ; Marked asthe-nopia; Spasm of accommodation ; Atropine instilled ; Relief withglasses.—February 17, 1894, Pauline J., aged thirty years, isin good general health, but has suffered a great deal from head-aches and pains in the eyes. It is almost impossible for her touse her eyes for close work o

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