Atlas of external diseases of the eye : including a brief treatise on the pathology and treatment / by O. Haab ; authorized translation from the German ; edited by G. E. DeSchweinitz.

Haab, O. (Otto), 1850-1931.

Date:: 1909

Credit: Atlas of external diseases of the eye : including a brief treatise on the pathology and treatment / by O. Haab ; authorized translation from the German ; edited by G. E. DeSchweinitz. Source: Wellcome Collection.

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$examiner’s eyesight in the study of ocular aff'ections; tlie same remark applies to the actual practice of ophthal- mology. It is therefore quite in order, before beginning a detailed description of the raost efficient raethod of ex- amination, to devote a few words to the xnost essential requisite in such an examination—the visual apparatus of the observer. I have often observed tliat medical men take up ophthalmology as a specialty without fully real- izing the prime importance of good eyesight in this branch of medicine. Although the use of a lens (corneal loupe) may to some extent correct defective eyesight in the examination of the anterior portion of the eye, yet in working with the oph- thalmoseope im perfect visual acuity is always a distinct disadvantage. A person with marked astigmatism suffers most in this respect both in examining the exterior and the fundus of a diseased eyeball; it is only with the greatest difficulty that he is able to see the most essential points, if they do not escape him altogether. A moderate degree of myopia (1-3 D) is less trouble- some than liypermetropia. As age advances the hyper- metropie eye requires convex glasses, which are a great obstacle to delicacy in examining and operating; or, at least, are very unpleasant and multiply the difficulties of the task. Binocular vision, the power to see with both eyes at once, is, of course, essential for obtaining a correct stereo- scopic picture; and as the diagnosis of many pathologic changes in the eye depends on a correct understanding of the appearances in the fundus, one who is able to study tlicm with one eye only is thereby deprived of a very important aid, especiallv when a rapid survey of a given phcnomenon in all its dimensions is desired. Again the lens can throw itself into the breach and make up for the absence of binocular vision ; but in operating its use is out of the question, or is at least a disadvantage. By long practice he who has but one sound eye at bis disposal, or whose eyes do not \york together properly, may pos-$