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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    inequality is not the immediate cause of strabismus, but, that it may become a cause thereof, under the influence of certain determining con- ditions existing in the non-deviating eye. The connexion which exists between binocular myopia and diverging strabismus, has not been passed over altogether without notice. Joh. Muller even writes of strabismus of myopic people (strabismus myopum)— Every one knows, he says,32 in commencing an explanation of the mode of the origin of this strabismus, that myopic people only use one eye ■when they look at near objects; while the other eye, also myopic, and its axis of vision obliquely deviating and directed towards distant objects, either sees not, or very indistinctly. This answers to the form which we have called relative diverging strabismus; it had already been described by Buffon, as occurring in his own eyes. In his own case he explains it by the difference of the images perceived by the two eyes ; but, in general, he places the cause in the unusual convergence of the eyes required in myopic people. The sight is fatigued and less distinct, he says, than when but one eye is used. To this cause Muller gives the first place; but he mentions, in addition, that the refraction is augmented by the convergence of the eyes. However in explaining afterwards why the optic axis also permanently deviates, more or less, from the normal direction, he only refers to the disease of the one eye as a consequence of the deviation. Even then he does not say that the deviation is constantly outwards, and he based his demonstrations, in a great measure, on this erroneous opinion. Ruete also speaks of the connexion between myopia and strabismus.33 We have already seen, that whilst, in general, progressive myopia, of a high degree, induces relative diverging strabismus with a tendency to become absolute ; yet it is only exceptionally that the convergence persists in vision at short distance; but in distant vision, it is maintained at the expense of parallelism of the lines of vision. These exceptional cases, in which the convergent strabismus, relative convergent, if one will, is complicated with progressive myopia, have been noticed by Ruete; but he did not notice the more general cases. He failed to convince himself of the presence of relative diverging strabismus, because, without doubt, he searched for it in cases of too slight a degree of myopia, where it is ordinarily wanting. In general one is but little satisfied when one consults the more recent but a» L. c, S. 237. » L. c, B. I., S. 226.