Eyestrain (commonly called asthenopia) / by Ernest Clarke.

  • Ernest Clarke
Date:
1892
Catalogue details

Licence: Public Domain Mark

Credit: Eyestrain (commonly called asthenopia) / by Ernest Clarke. Source: Wellcome Collection.

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    child with perfectly normal vision in both eyes, and 41 with normal vision in one eye—that is, less than one-third had fairly good sight. Unfortunately it was found im- possible to examine all the eyes under a mydriatic, but 25 of the worst cases were so examined and proved to be all cases of hyperopia or hyperopic astigmatism. The hyperopic or flat eye is the undeveloped eye, and most writers agree that the vision of young children is hyperopic. Horstmann, of Berlin, says that 88 per cent, of new-born children are hyperopic, and 86 per cent, between the ages of four and six. The majority of these hyperopic eyes are intended by nature to become emmetropic, but in a large number of cases instead of this happening, as development proceeds they overshoot the mark and become myopic, or astigmatism may develop, and this is the result of civilisation ! Roosa says that only a very small proportion of adults, say 7 per cent, have absolutely emmetropic eyes.^ From his private case book, out of a total of 6,455 patients he found 1,445 suffered from asthenopia, all of them having some abnormal condition of the eyes. Again he says, Not only all the world have faulty refraction, but very few people possess equilibrium of the ocular muscles, and out of 103 persons examined who complained of no trouble with their eyes—who read, wrote and sewed without headaches or any other symptom of strain—only i7,?>., 16 per cent., had muscular equilibrium. There is then no doubt that the perfectly normal eye is the exception. How is it then that asthenopia, common as it is, is not universal? The fact is, as Brudenell Carter^ has pointed out, the liability to asthenopia of any nation bears a distinct relation to the neurotic condition of the ' Trans. American Oph. Soc, 1878. 2 Hunterian Lectures, 1877.