Page:Popular Science Monthly Volume 67.djvu/748

742 will be found no muscle in the body which can endure continuous contraction except for a short time. Tests of holding the arm out straight, carrying a light satchel in one hand, etc., are familiar. Most muscles called into continuous action show that the continuity is an interrupted one, and that there are necessary rhythms of contraction, relaxation and rest. The genius of evolution, so far as the eye is concerned, never foresaw the demands to be made upon the organ by our modern life. In but one or two hundred years since printing, urbanization, commerce and the rest have sprung into existence, the entire process, ocularlyoccularly [sic] speaking, has been reversed; before this it was an intermittent and temporary function, while that of reading, writing, sewing and handicrafts demands a focussingfocusing [sic] of the image of objects at twelve or fifteen inches from the eye; this for millions has now become a continuous one. For all hyperopic and astigmatic eyes the act of accommodation is required for ten or fifteen hours a day, often for hours with hardly a moment's interruption. This unwonted demand requires the continuous innervation and contraction of the ciliary muscle. To comply necessitates an impossible task, considered physiologically; the result is eyestrain with its host of sequent diseases, far-away reflexes, headaches, nervous diseases and kinds of ill-health too numerous to enumerate.

If the hyperopia were alone present, and especially if the amount were alike in each of the two eyes, cerebral ingenuity could cope with it with far less disastrous results than are everywhere shown. The eyes are seldom alike and the evils multiply. But they become genuinely morbid with the complication of the usually-present astigmatism.

The ciliary muscle is a 'sphincter muscle' fashioned in a circular manner about a central point, and by its very nature it must act by an equal, or comparatively equal, contraction of all its parts. Astigmatism is a defect acting in a line across the structure, and hence to neutralize or compensate, the ciliary muscle is called to act against its structure and nature upon two opposite sides, those parts at right angles not acting. Hence the impossibility of overcoming the defect, at least in but a limited and partial, and always unnatural, way. The higher the astigmatism the greater the limitation and impossibility. In the high degrees it is frankly out of the question, and the retinal together with the sensation-making function is hurt by the false and blurred image, and vision deteriorated. 'The old ophthalmology,' still ruling unquestioned in Europe and largely everywhere, looks upon the correction of astigmatism by glasses only as a means of giving better vision, and so corrects only the large errors. It forgets that in these large optical defects the ciliary muscle renounces effort, and that the smaller ones are precisely those which produce the worst morbid results, because the strain of accommodation, or continuous