. Babyhood . gested by topicstreated in any other part of the the series can thus be made stillmore helpful. 148 BAB YHOOD. CROSS-EYES OR SQUINT. BY CHARLES H. MAY, , Instructor in Ophthalmology, New York Polyclinic : Clinical Assistant at the Eye and liar DepartmentCollege-of Physicians and Surgeons, and at the Manhattan Eye and Ear Hospital, New York, etc. THE term cross-eyes is one popularlyemployed to designate a condition inwhich the axes of the two eyes are not di-rected toward the same point. It is a pro-vision of nature that, to see an object dis-tinctly with the
. Babyhood . gested by topicstreated in any other part of the the series can thus be made stillmore helpful. 148 BAB YHOOD. CROSS-EYES OR SQUINT. BY CHARLES H. MAY, , Instructor in Ophthalmology, New York Polyclinic : Clinical Assistant at the Eye and liar DepartmentCollege-of Physicians and Surgeons, and at the Manhattan Eye and Ear Hospital, New York, etc. THE term cross-eyes is one popularlyemployed to designate a condition inwhich the axes of the two eyes are not di-rected toward the same point. It is a pro-vision of nature that, to see an object dis-tinctly with the two eyes, both must be fixedupon it. And we can only see one objectwell at a time ; those outside the point offixation may be seen, but imperfectly. Henceto adapt the organ of vision to our needsprovision is made for their rapid movementin all directions, so that successive fieldsmay be explored with rapidity. MUSCLES OF THE EYEBALL. This mobility of the eyeball is accom-plished by means of six small muscles,. the lids. It is by the action of these thatwe can turn the eyes at will in any givendirection. Another provision of nature isthat there shall be harmonious action be-tween the movements of the two eyes ; thatis, when one eye turns upward the other ac-companies it without any effort on our part ;when we examine an object held up close,both eyes turn inward, etc. This, it will be understood, is a necessaryprovision for distinctness of form and out-line ; for when we make use of one eyealone everything looks flat and wanting inprojection. Thus the experiment may bemade of closing one eye and looking at anunfamiliar object, then opening both eyesand noticing the change ; the difference inappearance will be marked, and thevalue of binocular vision become ap-parent. Having thus explained themuscular apparatus of the eye and itsfunction in vision, the following linesabout cross-eyes will be better under-stood. VARIETIES OF SQUINT. i. The muscle which lifts the upper lid Cross-ey
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