Constitutional conditions combined with ametropia the cause of asthenopia / by D. B. St. John Roosa.

  • Roosa, D. B. St. John (Daniel Bennett St. John), 1838-1908.
Date:
[1891]
Catalogue details

Licence: Public Domain Mark

Credit: Constitutional conditions combined with ametropia the cause of asthenopia / by D. B. St. John Roosa. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    percentage of emnietropes. Emmetropia has been proved to be the rarest of conditions. I myself had something to do in originating the investigations that indicate this in my paper published in 1878,* entitled An Examination under Atropine of the Refractive State of Eyes with Normal Vision ■§-§-, and which has never been affected with Asthenopia or Inflammation. This paper and later inves- tigations by other ophthalmologists embracing many cases and more thorough examinations, especially as to astigma- tism, have brought most ophthalmologists to believe what I have stated above—that emmetropia is an exceedingly rare condition. Writers upon this subject should at least at- tempt to invalidate the statistics of those who assert that emmetropia is an ideal rather than a real condition before they base so many arguments upon what we think have been proved to be incorrect premises. Noyes, a writer for whom we all have great respect, in a paper upon Muscular Asthenopia, just published,! finds forty-seven per cent, of emmetropia. I do not know of any other recent authority who shares his views. Four, instead of forty, per cent, would be the most that I would admit. Of fifty persons recently examined for me by Dr. A. B. Dey- nars, one of my assistant surgeons at the Manhattan Eye and Ear Hospital, thirty-three had astigmatism, saying nothing of hypermetropia and myopia, and they were all carefully chosen as persons who never suffered from as- thenopia. It is, I think, begging the whole question at issue to urge as an argument that the determination of hypermetro- pia and myopia i8 thoroughly understood by any compe- tent ophthalmologist. The question in this discussion is in part, What constitutes ametropia and how is it detected? * Transactions of the American Ophthalmological Society, 1878. \ Ibid., 1890.