Perfect Sight Without Glasses. William Horatio Bates

11. The Refraction and Accommodation of the Eye and their Anomalies, authorized translation by Culver, 1886, p. 151.

12. Physiologic Optics, authorized translation by Weiland, 1904, p. 163. Marius Hans Erik Tscherning (1854 - ) is a Danish ophthalmologist who for twenty-five years was co-director and director of the ophthalmological laboratory of the Sorbonne. Later he became professor of ophthalmology in the University of Copenhagen.

13. The Hygiene of the Eye in Schools, English translation edited by Turnbull, 1886, p. 23. Hermann Cohn (1838-1906) was professor of ophthalmology in the University of Breslau, and is known chiefly for his contributions to ocular hygiene.

14. Lessons in Elementary Physiology, sixth edition, 1872, p. 231.

15. On the Anomalies of Accommodation and Refraction of the Eye, p. 13.

16. Krankheiten des Auges, 1853-56, vol. iii, D. 219, et seq.

17. Ueber die Ursachen und die Entstehung der Kurzsichtigkeit, 1876. Vorwort.

18. Handbuch der physiologischen Optik, vol. i, pp. 124 and 145.

19. Ibid, vol. i. P. 144.

      20. Physiologic Optics, p. 166. Herman- Ludwig Ferdinand von Helmholtz (1821-1894) whose observations regarding the behavior of images reflected from the front of the lens are supposed to have demonstrated that the curvature of this body changes during accommodation.

21. Absence of the lens.

22. On the Anomalies of Accommodation and Refraction of the Eye, p. 320.

23. Archiv. f. Ophth., 1855, vol. ii, part 1, p. 187 et seq. Albrecht von Graefe (1828-1870) was professor of ophthalmology in the University of Berlin, and is ranked with Donders and Arlt as one of the greatest ophthalmologists of the nineteenth century.

24. Klin. Montasbl. f. Augenh., Erlangen, 1872, vol. x, p. 39, et seq.

25. Archiv. f. Ophth., 1873, vol. xix, part 3, p. 107.

26. Flint: Physiology of Man, 1875, vol. v, pp. 110-111.

27. Davis: Accommodation in the Lensless Eye, Reports of the Manhattan Eye and Ear Hospital, Jan., 1895. The article gives a review of the whole subject.

28. An instrument for measuring the curvature of the cornea.

29. Nov., 1893, p. 932.

30. Inasmuch as the eye is inextensible, it cannot adapt itself for the perception of objects situated at different distances by increasing the length of its axis, but only by increasing the refractive power of its lens. - De Schweinitz: Diseases of the Eye, eighth edition, 1916, pp. 35-36.

      CHAPTER IV - THE TRUTH ABOUT ACCOMMODATION AS DEMONSTRATED BY EXPERIMENTS ON THE EYE MUSCLES OF FISH, CATS, DOGS, RABBITS AND OTHER ANIMALS

       Table of Contents

      THE function of the muscles on the outside of the eyeball, apart from that of turning the globe in its socket, has been a matter of much dispute; but after the supposed demonstration by Helmholtz that accommodation depends upon a change in the curvature of the lens, the possibility of their being concerned in the adjustment of the eye for vision at different distances, or in the production of errors of refraction, was dismissed as no longer worthy of serious consideration. "Before physiologists were acquainted with the changes in the dioptic system,1 says Donders, "they often attached importance to the external muscles in the production of accommodation. Now that we know that accommodation depends on a change of form in the lens this opinion seems scarcely to need refutation." He states positively that "many instances occur where the accommodation is wholly destroyed by paralysis, without the external muscles being the least impeded in their action," and also that "some cases are on record of paralysis of all or nearly all of the muscles of the eye, and of deficiency of the same, without diminution of the power of accommodation."2

      If Donders had not considered the question settled, he might have inquired more carefully into these cases, and if he had, he might have been less dogmatic in his statements; for, as has been pointed out in the preceding chapter, there are plenty of indications that the contrary is the case. In my own experiments upon the extrinsic eye muscles of fish, rabbits, cats, dogs and other animals, the demonstration seemed to be complete that in the eyes of these animals accommodation depends wholly upon the action of the extrinsic muscles and not at all upon the agency of the lens. By the manipulation of these muscles I was able to produce or prevent accommodation at will, to produce myopia, hypermetropia and astigmatism, or to prevent these conditions. Full details of these experiments will be found in the "Bulletin of the New York Zoological Society" for November, 1914, and in the "New York Medical Journal" for May 8, 1915; and May 18, 1918; but for the benefit of those who have not the time or inclination to read these papers, their contents are summarized below.

      There are six muscles on the outside of the eyeball, four known as the "recti" and two as the "obliques." The obliques form an almost complete belt around the middle of the eyeball, and are known, according to their position, as "superior" and "inferior." The recti are attached to the sclerotic, or outer coat of the eyeball, near the front, and pass directly over the top, bottom and sides of the globe to the back of the orbit, where they are attached to the bone round the edges of the hole through which the optic nerve passes. According to their position, they are known as the "superior," "inferior," "internal" and "external" recti.- The obliques are the muscles of accommodation; the recti are concerned in the production of hypermetropia and astigmatism.

      Fig. 13. Demonstration Upon the Eye of a Rabbit that the Inferior Oblique Muscle is an Essential Factor in AccommodationNo. 1. - The inferior oblique muscle has been exposed and two sutures are attached to it. Electrical stimulation of the eyeball produces accommodation as demonstrated by simultaneous retinoscopy.No. 2. - The muscle has been cut. Electrical stimulation produces no accommodation.No. 3. - The muscle has been sewed together. Electrical stimulation produces normal accommodation.

      In some cases one of the obliques is absent or rudimentary, but when two of these muscles were present and active, accommodation, as measured by the objective test of retinoscopy, was always produced by electrical stimulation either of the eyeball, or of the nerves of accommodation near their origin in the brain. It was also produced by any manipulation of the obliques whereby their pull was increased. This was done by a tucking operation of one or both muscles, or by an advancement of the point at which they are attached to the sclerotic. When; one or more of the recti had been cut, the effect of operations increasing the pull of the obliques was intensified.

      Fig. 14. Demonstration Upon the Eye of a Carp That the Superior Oblique Muscle Is Essential to Accommodation.No. 1. - The superior oblique is lifted from the eyeball by two sutures, and the retinoscope shows no error of refraction. No. 2. - Electrical stimulation produces accommodation, as determined by the retinoscope. No. 3. - The muscle has been cut. Stimulation of the eyeball with electricity fails to produce accommodation. No. 4. - The divided muscle has been reunited by tying the sutures. Accommodation follows electrical stimulation as before.Fig. 15. Demonstration Upon the Eye of a Rabbit That the Production of Refractive Errors Is Dependent Upon the Action of the External Muscles. The String Is Fastened to the Insertion of the Superior Oblique and Rectus MusclesNo. 1. - Backward pull. Myopia is produced.No. 2. - Forward pull. Hypermetropia is produced.No. 3. - Upward pull in the plane of the iris. Mixed astigmatism is produced.Fig. 16. Demonstration Upon the Eye of a Fish That the Production of Myopic and Hypermetropic Refraction Is Dependent Upon the Action of the Extrinsic Muscles.Suture tied to the insertion of the superior rectus muscle. By means of strong traction upon the suture the eyeball is turned in its socket, and by tying the thread to a pair of fixation forceps which grasp! the lower jaw, it is maintained in this position. A high degree of mixed astigmatism is produced, as demonstrated by simultaneous retinoscopy. When the superior oblique is divided the myopic part of the astigmatism