Ward McLean

“ When we see any object clearly, it is because the rays of light reflected or radiated from it enter the eye and produce a perfect picture of the object upon the retina. But the perfection of the picture depends upon the distance, size, and illumination of the object relatively to the powers and condition of the eye. The distance determines the angle at which the rays enter the eye. Whatever this angle, the rays must converge upon the retina, or the picture will be defective. ”

“ The normal location of the retina is that point at which parallel rays are converged, the lens being at rest. But if the eyeball loses its normal shape, and becomes elongated in the direction of its visual axis, the retina is thereby set back beyond the focal point. Convergence may be effected within the normal distance, but never beyond it; for, while the lens may become changed from its passive state to one of greater convexity, it cannot assume a convexity less than that of its passive state. ”

“ A prolonged and steady looking at an object or at objects near the eye, though at proper distance, without rest or frequent change of the visual focus, as in long and absorbed novel-reading, intense study, or persistent diligence in needlework.
4. The practice of reading or otherwise using the sight at too short range. This results in part from insufficient light; or from its faulty direction, so that the hand or body throws a shadow on the page; or so that the direct rays fall upon the eye, causing undue contraction of the pupil, while the page is in shadow. ”

“ Loring advocated examinations of the sight of all children when they first enter school, and at such subsequent stages of their education as might seem desirable. The position of a child's seat relatively to the blackboard, etc., would often be governed by such an examination. He thought, too, that glasses would be recommended in some cases by the examining oculist—a permanent official he would have him to be—and that, if necessary, they should be furnished at the public expense, or out of some special fund; the glasses to be worn during school-hours at least, if not continuously. ”

“ This convergence it is the office of the lens to effect. From remote objects the rays are parallel, or nearly so. These, passing through the lens, are converged by it upon the retina. As the distance diminishes, rays entering the eye from any given point of the object become more and more divergent. Now, unless there be a corresponding increase in the convexity of the lens, these divergent rays will not be focalized at the same point as were the parallel rays; because, with the same power of lens, the focal distance must increase as the rays diverge ”

“ As a class, the colored people of New York, prior to this generation, had very limited educational advantages, and the occupations which tax the sight, like engraving, etc., have never been known among them. But as these 457 subjects are now receiving the best school-training that the city affords, the superior condition of their sight must be referred to their freedom from hereditary tendency to myopia. ”

“ But, if it be impracticable to apply the atropia, then the ophthalmoscope [5] must be resorted to, as offering the nearest approach to certainty of results when the accommodating-muscle cannot be paralyzed, because its contraction is not very likely to occur under the operation of that instrument. Thus provided, the oculist proceeds to examine the interior of the eye, and, his own eye being normal, and his own accommodation relaxed, if he sees the retina of the examined eye perfectly, he pronounces the refraction to be correct ”

“ I look forward to the time when these children, who from this single peculiarity are placed at so serious a disadvantage in the struggle for life, shall find the relief that science is ready to afford them, and which would remove the weight that would otherwise prove a serious hinderance in their course. ”

“ When the eye and the memory are sufficiently trained to easily recognize and name each letter and figure at sight, and when some knowledge has been gained of the power of letters and figures in combination, then the same forms in books will be at once familiar as old acquaintances, and may be studied without straining the sight. To train the hand without straining the sight presents a greater practical difficulty. ”

“ The investigations of Dr. Peter A. Callan belong in this category, with a qualification. He examined the sight of 457 colored-school pupils, aged from five to nineteen years, of the New York public schools, Nos. 3 and 4, and he found but 2.6 per cent, of them near-sighted. This field was selected because it was thought to furnish the nearest approach to the normal eye to be found in this locality. The Southern freedmen, he thinks, would afford the best possible field for this special line of investigation. ”

“ Sometimes the examining oculist has acquired the power to perfectly relax his accommodation at will. But the relaxation of the accommodation of the subject, as well as that of the examiner, is essential to entire accuracy. ↑ A small mirror with a hole in the centre. The mirror is held close to the patient's eye, so as to reflect into it the light of a gas-jet back of him. The oculist then places his eye close to the hole, and looks into the illuminated interior of the eyeball. ↑ This is not a disease, like near-sight, but a condition; and it is not acquired, but is congenital, always. ”

“ Not only is the near-sighted person not in a condition to discharge all civil duties, not only is he limited in the choice of his position in society, but in the higher degrees near-sight leads to disturbance of the power of vision, and threatens its subject with incurable blindness. ”

“ But while it appears to be conceded that near-sight is of infrequent occurrence among the illiterate classes, the question is a very natural one, "Have examinations been made, for comparison, of the eyes of any classes of young persons other than those engaged in study?" ”

“ A POPULAR error has long existed as to the real character of short-sightedness; and even medical men have to some extent participated in it. It is not an indication of strength of vision. It is a disease, always inconvenient, and sometimes dangerous. ”

“ The startling extent, the rapid increase, and the serious character, of these visual defects in our schools, and the fact that the greater part of them originated there, and might have been prevented, should awaken universal interest, that the proper remedies may be applied to arrest the evil as speedily and effectually as possible. ”

“ To be sure that you have sufficient light, and that your position be such that you not only avoid the direct rays upon your eyes, but that you also avoid the angle of reflection. In writing, the light should be received over the left shoulder. ”

“ The contraction and consequent thickening of the muscles which pull the two eyes inward, so as to focalize the sight upon a near object, causes a side-pressure, and a corresponding transverse or length-wise protrusion. The nearer the object, the stronger must be this action of the muscles, and the more marked the effect. ”

“ If it were thus found—and I can scarcely doubt that it would be so—that near-sight is progressive in cultivated society, this would be a very serious phenomenon, and we should earnestly think of means of arresting this progression. ”

“ The prone position of the head causes the blood to settle in the eyeballs, increasing the tension of the fluids, exciting inflammation and consequent softening of the coatings, and resulting in permanent distention. ”

“ In the large schools, of course, all the children cannot go to the black-board. But a considerable practice in drawing large lines and simple objects on good-sized slates, in a sort of free-hand style, should precede the formation of letters and figures ”

“ He then describes the process of individual examination: Haifa dozen scholars at a time were sent into a class-room, on one of the walls of which had been hung a card of letters known to oculists as "Snellen's test-types." ”