The action and uses of prismatic combinations / by Archibald Percival.

  • Percival, A. S. (Archibald Stanley), 1862-
Date:
[1881]
Catalogue details

Licence: Public Domain Mark

Credit: The action and uses of prismatic combinations / by Archibald Percival. 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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    to avoid Symptoms arising from its persistence (Cf. methods A and B). * The Solution of these questions is urgently needed, as the very principles of treatment are involved in them. Indeed, a complete investigation of the strengths of the ocular muscles, and their functional relations todifferent degress of accommodation, demands such prolonged and repeated examinations that they would be quite impossible to carry out in practice with each patient. It is imperative, therefore, to determine what are the points to which we may confine our attention. I have dealt with this complicated subject at some length, so that its difficulties may be clearly stated and fairly faced. They can only be solved by data furnished by clinical experience. I have latterly adopted the procedure of correcting all the refractive error, and so much of the convergence defect as will enable the eyes to maintain their necessary direction without calling for special exertion (A). I have met with some success by acting on this principle, but my experience is not yet large enough to justify me in giving expression to a dogmatic opinion. It is at such a meeting as the present that there is an opportunity of throwing light on the obscurities of the subject by free discussion, based on clinical Observation. It is most desirable that further progress should be made in rendering the methods of dealing with muscular asthenopia more precise and scientific. It is obviously to the absence of such precision and accuraey that the not uncommon failure in treat- ment is to be traced. (*) In A the abnormality of the rclation is allowed to persisl in its entirety, but in B only in part.