On the anomalies on accommodation and refraction of the eye : with a preliminary essay on physiological dioptrics / by F. C. Donders ; translated from the author's manuscript by William Daniel Moore.

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

Credit: On the anomalies on accommodation and refraction of the eye : with a preliminary essay on physiological dioptrics / by F. C. Donders ; translated from the author's manuscript by William Daniel Moore. 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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    From the external appearance, I had scarcely a doubt of the existence of H. At the distance of 3 the child saw, with her head aslant and her eyelids nearly closed, No. Ill of Snellen; smaller letters she did not see; with 1/6 on the contrary, she saw II at 8: so the proof was supplied. S was =1/2. Probably astigmatism exists, to be more fully investigated at a somewhat later period, when the patient shall be able to give a more accurate account of herself. Meanwhile, she may provisionally use 1/6 in learning,—if she chooses she may also wear them habitually. 'This she would rather not do'. § 24. Strabismus convergens, the Result of H Strabismus is a deviation in the direction of the eyes, in consequence of which the two yellow spots receive images from different objects. In strabismus the visual lines do not cross one another in. the point it is desired to observe; only one of the two, that of the undeviating eye, is directed to that point. Under this deviation not only does the ex- pression of the face suffer from the want of symmetry in its most elo- quent parts, but the power of vision, at least in one of the eyes, is usual- ly disturbed, and the squinter always loses the advantage of binocular vision. We now know that by far the greater number of cases of strabismus are connected with anomalies of refraction. According to the direction of the deviation, two forms of oblique vision are specially to be distinguished: strabismus convergens and strabismus divergens. The main result of our investigation may be expressed in these two propositions. 1. Strabismus convergens almost always depends upon hypermetropic 2. Strabismus divergens is usually the result of myopia. We have here to treat only of strabismus convergens. Experience, in the first place, shows, that strabismus convergens is, in the great majority of cases, combined with H. In 172 cases investi- gated by us, H was 133 times proved to exist in the undeviated eye. . . . In thirteen cases difference of refraction of the two eyes was recorded; ... at least five times paralysis had gone before; three times there was complication with congenital cataract, twice with nystagmus.—It is evident how greatly H preponderates: it occurs in about 77 per cent, of the cases. And yet I am convinced, that if we could investigate without distinction all cases of strabismus convergens which occur in a given population, H would be met with relatively still more frequently. In the first place, ordinary cases of strabismus convergens are seldom brought to the oculist, and these are precisely the cases in which H is the only cause: if inflammation, paralysis, or any special complications be present, the patients do not dealy to call in help; and thus, in pro- portion to the whole, a greater number of these exceptional cases comes