Eyestrain (commonly called asthenopia) / by Ernest Clarke.

Ernest Clarke

Date:: 1892

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

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$to the present we have no proof that such diseases as epilepsy and chorea owe their existence to eyestrain, but eyestrain, Hke any other peripheral irritation, such as indigestion, &c., may start an attack in an epileptic or choreic patient; and if the eyestrain is removed the peri- pheral irritation is likewise removed, and the attacks are more likely to be fewer or milder, or even disappear altogether. VI. RELATIVE FREQUENCY OF ASTHENOPIA.— Eyestrain is chiefly caused by some abnormal condition of the eyes. What is the proportion of normal vision to abnormal vision ? Jackson, of Philadelphia, in a paper on The Absolute Static Refraction of the Eye,^ reports that out of 4,000 eyes examined during complete paralysis of accommoda- tion, only 51, i.e.^ 1.3 per cent, were normal. Randall reports an examination of the eyes of 142 medical students. He found only 16 really emmetropic without the use of a mydriatic, which would probably have considerably reduced even this low average.^ Again, in a paper criticising the various statistics on record, based on the examination of the refraction in large schools, &c., numbering 115 separate investigations, and including 146,522 examinations, he says, Emmetropia, in a mathematically strict sense, has probably no existence. Approximate emmetropia (Ametropia < ± .5 D) is in- frequent in all ages, probably at no epoch exceeding 10 per cent. ^ Out of a school of 150 children of the average age of eight years, lately examined by me, I only found one ' Trans, of the Atnerican Oph. Soc, vol. v., p. 435. ' Americmi Journal of Oph.^ vol. viii., p. 40. ■■' American Journal of the Med. Sciences, July, 1885.$

Eyestrain (commonly called asthenopia) / by Ernest Clarke.

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