[Transactions of the American Ophthalmological Society] ; Transactions of the American Otological Society : second annual meeting, Newport, R.I., July, 1869.
- American Ophthalmological Society
- Date:
- [1869]
Licence: Public Domain Mark
Credit: [Transactions of the American Ophthalmological Society] ; Transactions of the American Otological Society : second annual meeting, Newport, R.I., July, 1869. 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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![ir we now divide one of the interni, say the left, c, a certain ainoimt of divergence of tlie optical axis, x, from its former position would be the immediate result, exactly as it is in the common o])cration for strabismus. This divergence may be represented on the diagram by the dotted line extending from the point 1> to the point A, and it is self-evident that the ten- sion on the interims, in order to make x regain its former position—i.e. intersect with its fellow at o—must be as much’ • greater, after the operation than it was before, as the diverg- ence is greater. Now what holds good for one degree of convergence holds good for all; and as we have increased the amount of tension on the interni for every given degree of con- vergence, we have, according to the law, also increased tlie amount of accommodation, or, as Aon Graefe more exactly ex- presses it, we have disjdaced the region of relative accommo- dation toward the absolute near jioint. This displacement may be represented by diagram A in Fig. 1. The whole rela- tive accommodation will be seen to liave been displaced to- ward the eye; tbc amount of force actually expended, repre- sented in the line by the distance lictween o and R', is seen to be much less, while that held in reserve is much greater tlian befoi-Q the operation. There can be no doubt then as to tlie truth of the statement that by cutting the interni we increase the amount of tension for a given degree of convergence, and that by so doing we do indeed, temporarily at least, displace the relative accommoda- tion. But then this can only happen without exception, when binocular vision was jirescnt before the operation and is main- tained after it. We can, therefore, by no means agree with the illustrious author when he continues liy saying: “ When, on the contrary, in consequence of hyjiermetropia, convergent squint has resulted and characterizes the patient, not only at work, but at other times, I am then an advocate for tenotomy, which then in all respects appears rational. The better position of the eyes, which is obtained by the operation, will, since a greater tension of the interni is regiresented, exer- cise the same effect on the range of relative accommodation as did the original condition of the convergence, which was not only disfiguring, but which threatened the functions of](https://iiif.wellcomecollection.org/image/b22449784_0026.jp2/full/800%2C/0/default.jpg)
