On the pathogeny of squint / by Professor Donders ; translated from the German, with a preface, by E. Perceval Wright.

  • Donders, F. C. (Franciscus Cornelis), 1818-1889.
Date:
1864
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Licence: Public Domain Mark

Credit: On the pathogeny of squint / by Professor Donders ; translated from the German, with a preface, by E. Perceval Wright. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Von Graefe has described8 a very marked case of this nature under the name of an apparent incongruence of the retinae, by the anomalous entrance of the optic nerve, the yellow spot at the same time, with the optic nerve was thrown very much on the inner side in one of the eyes. He compares this case with another of true incongruence of the retinae, in which the yellow spot might be found on the nasal side of the optic nerve in one of the eyes. I cannot conceal the fact that this last case is to me a very problematical one. On account of the imperfect sensibility of the portions of the retina, employed in fixation, another explanation might very easily be given, of which von Graefe has himself thought. If, therefore, I cannot admit that any other forms of incongruence of the retina? are demonstrated besides those which I have written of under the name of apparent strabismus, I willingly apply to these the express words of von Graefe when he says:— I might not regard this case as one of incongruence of the retina?, but as an unsymmetrical development of the two halves of the optic bulb. The hypothesis of de la Hire,9 already controverted by Jurin and Buffon, but revived, in our days, by Pickford,10 viz., that convergent strabismus commonly depends on the incongruence of the retinae, does not, after the researches of von Graefe,11 deserve to be any further discussed. 8 Archiv fur Ophth. Bd. i., 1, S. 435. Ibid, S. 105. Neither am I convinced by the cases which Dr. Alfred Grafe gives in his clear and concise work (Klinischa Analyse der Motilitatsstorungen des Auges. Berlin, 1858. S. 228). I see that Arlt also considers the existence of strabismus incongruus as problematical (Die Krankheiten des Auges. Band iii., S. 320). 9 Priestley, Geschichte der Optik, tibersetzt von Klugel Leipsig, 1775, S. 408. 10 Archiv fur Physiologsche. Heilkunde, 1842, S. 590. 11 Von Graefe's important observations on the changes in the projection of the optic axes in strabismus have given origin to numerous treatises on binocular vision, in ■which Miiller's theory of identical points has been controverted. What has been ■written above is so closely connected with this subject that I cannot refrain from briefly giving my opinion on it. It is necessary to distinguish between the projection of the field of vision and the projection of a point in that field (vide Hollandische Beitrage z. d. Anatom. and Physiolog., Wissenschaften, 1848, t. 7, p. 105 and Seq.) The projection of the field of vision depends on the position of the eye, and on the direction of the line of vision which we assume to be at command. To what part of the so projected field of vision we further project a certain point is decided by the spot which its image occupies on the retina. In myopia, the image on the retina is larger than what it would be in an emmetropio eye, the angle being the same, and this in proportion as the distance between the optic