On insufficiency of the power of convergence / by E. Landolt.
- Edmund Landolt
- Date:
- [1886]
Licence: Public Domain Mark
Credit: On insufficiency of the power of convergence / by E. Landolt. Source: Wellcome Collection.
Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)
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![ON INSUFFICIENCY OF THE POWER OF CONVERGENCE. By Dr. E. Landolt, Paris. [Translated under the author's direction by W. T. Law, M.D., F.R.C.S-] For the proper accomplishment of binocular vision two conditions are necessary:—I. The image of the object must be simultaneously formed upon the fovea centralis of each eye. 2. This image must be distinct. The first condition is fulfilled when the visual lines cross at the point of fixation. This depends upon the motor apparatus, whose function is to give to the eyes the convergence required by the distance of the object. The realisation of the second condition concerns the optical apparatus of the eyes. Of these two elements of binocular vision the former is by far the more important. Without proper direction of the eyes such vision is absolutely impossible, while it may very often be effected satisfactorily to the individual, in spite of imperfection of the retinal images. Moreover, it is very easy to correct optical errors by glasses, while it is much more difficult to remedy a defect of movement or direction in the eyes. Alterations in the latter are very frequent. They often give rise to an asthenopia, in the treatment of which i there is yet much to be desired, for we are still far from sufficiently understanding the functions of the motor! apparatus in relation to binocular vision, or the means bf correcting their anomalies. For a long time I have, studied this important question, and would here venture to give a resume of the results at which I have at present arrived. Should these, however, fail to solve the numerous questions connected with the subject, I hope they may at least help to point out the way of conducting the investigation. Ophth. Review, Vol. V. Nos. 57 and 58. July and August, 1886.](https://iiif.wellcomecollection.org/image/b21647161_0003.jp2/full/800%2C/0/default.jpg)
