File:The cure of imperfect sight by treatment without glasses (1920) (14578335487).jpg

Identifier: cureofimperfects00bate (find matches)
Title: The cure of imperfect sight by treatment without glasses
Year: 1920 (1920s)
Authors: Bates, William Horatio, 1860-1931
Subjects: Eye Eye Eyeglasses
Publisher: New York City : Central Fixation Publishing Co.
Contributing Library: Yale University, Cushing/Whitney Medical Library
Digitizing Sponsor: Open Knowledge Commons and Yale University, Cushing/Whitney Medical Library

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ture. It is strange,however, that these difficulties have not in any way dis-turbed the universal belief that the lens does change. When the lens has been removed for cataract the patientusually appears to lose his power of accommodation, andnot only has to wear a glass to replace the lost part, buthas to put on a stronger glass for reading. A minority ofthese cases, however, after they become accustomed to thenew condition, become able to see at the near-point withoutany change in their glasses. The existence of these twoclasses of cases has been a great stumbling block to ophthal-mology. The first and more numerous appeared to sup-port the theory of the agency of the lens in accommodation;but the second was hard to explain away, and constitutedat one time, as Dr. Thomas Young observed, the grandobjection to this idea. A number of these cases of ap-parent change of focus in the lensless eye having beenreported to the Royal Society by competent observers, l Physiologic Optics, p. 166.
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Herman Ludwig Ferdinand von Helmholtz (1821-1894^1 whose observations regarding the behavior of images reflected fromthe front of the lens are supposed to have demonstrated that thecurvature of this body changes during accommodation. 31 32 Evidence for Accepted Theory of Accommodation Dr. Young, before bringing forward his theory of accom-modation, took the trouble to examine some of them, andconsidered himself justified in concluding that an error ofobservation had been made. While convinced, however,that in such eyes the actual focal distance is totally un-changeable, he characterized his own evidence in supportof this view as only tolerably satisfactory. At a laterperiod Donders made some investigations from which heconcluded that in aphakia1 not the slightest trace of ac-commodative power remains.2 Helmholtz expressed simi-lar views, and von Graefe, although he observed a slightresiduum of accommodative power in lensless eyes, didnot consider it sufficient to discredit the theory

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