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
Catalogue details

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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    seen which are situated at a definite finite distance (Fig. 2, t.); in the second case they are, at no distance, accurately seen—for the rays, in falling upon the cornea, must, in order to unite in the retina, already converge towards a point situated behind the eye (Fig. 3, i.). Professor Donders's paper proves that in this last class of eye converging squint is very often found, whereas in the second we very frequently find diverging squint. For example, a person with one eye hypermetropic, in order to try and obtain more distinct vision, at first slightly converges this eye; by this, however, double vision occurs, which is more distressing than even the previous indistinct vision ; and, to avoid this, the eye either converges a little more or the image of the eye is suppressed. In the latter case, the sight of this eye becomes impaired, and in process of time is completely lost; in the former, a well-marked converging squint arises. This manifests itself about the fifth year ; and as long as it only occurs intermittingly, with fixing of an object, its development may be prevented by wearing convex glasses so as to neutralize the existing hyper- metropia. Professor Donders first observed this in a young man, who, in his eighteenth year, began, for the first time, to squint in fixing. He had hypermetropia equalling ^jth. After wearing the proper glasses for two days, he began to be no longer able, for the sake of seeing accurately, to make one eye deviate. He then also saw at a distance indistinctly. And it was not until half an hour after putting off the spectacles that he again succeeded in producing the squint, and thereby distinguishing accurately. By continuing to wear the spectacles, the squint ceased to be produced, and the tendency to it was completely lost. If the squint sets in very early in life, wearing spectacles is, of course, attended with difficulties, and parti- cularly when the patients are of the female sex; they are unwilling to be condemned to wear glasses during their whole life. In such cases it is generally sufficient to advise them to look several times daily, for some minutes, with the deviating eye alone, which practice is sufficient to pre- vent the diminution of the acuteness, and the limitation of the field of vision; at a later period—when the squint is confirmed—the operation of tenotomy is performed. Where the patient prefers obviating the squint by wearing proper glasses, Professor Donders willingly consents, and has found the object almost invariably obtained. Dr. Mooren,* too, has recently stated that where a tolerably high degree of hypermetropia existed, he has, in the first stage of strabismus, prescribed with good a Klinische Monatsblatter fur Augenheilkunde. B 1, H 1, 1863.