Refraction / by J.G. Parsons.

  • Parsons, J.G.
Date:
1907
Catalogue details

Licence: In copyright

Credit: Refraction / by J.G. Parsons. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    ance of nervous equilibrium and expenditure of nervous energy brings about the various reflex disturbances, some of which have been referred to. This is capable of clinical demonstration, as is shown by the records of any oculist. It may be investigated experimentally. Snell made a graphic demonstration by placing cylindrical lenses in front of a properly fo- cused camera. With an artificially produced astigmatism of one-half or three-fourths diop- ter, the camera produces reproductions of a printed paragraph which are so blurred that it makes one almost dizzy to look at them on the printed page. If any one doubts what this would do if placed in front of a practically nor- mal eye, let him try it, and imagine what must be the efifect on one of having the eye con- stantly in such an abnormal state. Gould claims that 90 per cent of headaches are due to eye-strain, and the observations of most careful refractionists would seem to indicate that the percentage is not much too high. Our case-records are full of evidence to show that most frequent headaches are of ocular origin. Gould has shown that the principal cause of migraine is ocular, and may be relieved by the correction of astigmatism. In a recent is- sue of the Journal of the A. M. A., Reik in- dorses Gould’s statements as to eye-strain as an etiologic factor in epilepsy, and cites sev- eral cases in point. As previously quoted, Musser recognizes eye-strain as a factor in the cause of stomach trouble, and suggests the tendency of continued functional disorder to develop into organic disease. Gould has also shown how scoliosis may be caused in school children by astigmatism at such an axis that tilting of the head is necessary in order to ob- tain clear vision. With such evidence before us, substantiated by such men as Gould, Reik, Oliver, Standish, Snell, and many other eminent ophthalmol- B—