Cases illustrating various types of scotoma in the visual field : portion of a lecture on "The visual field as a factor in diagnosis" delvered before the J. M. Da Costa Medical Society of the Jefferson Medical College / by G. E. de Schweinitz.

  • De Schweinitz, G. E. (George Edmund), 1858-1938.
Date:
1909
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Licence: In copyright

Credit: Cases illustrating various types of scotoma in the visual field : portion of a lecture on "The visual field as a factor in diagnosis" delvered before the J. M. Da Costa Medical Society of the Jefferson Medical College / by G. E. de Schweinitz. 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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    as before, was ^ barely. There had been more absorption of the pig- mented epithelium, and between the disk and the macula a patch of superficial atrophy of the choroid had appeared, while in the periphery there was marked exposure of the deeper choroidal vessels, with dark, lozenge-shaped islands lying between them. The disk was a little more prominent, and the veiling of the nasal edges more marked. The field of vision was practically unchanged, save only increased peripheral contraction and some enlargement of the scotoma (see Fig. 5). The patient is now under treatment for a sarcocele, following an injury, .probably sarcomatous in nature. Remarks.—It is probable that careful testing of the visual field of cases of glaucoma would reveal the presence of scotomas more fre- quently than the ordinary descriptions of this disease would lead one to suppose. Bunge (quoted by Berry) found a central or paracentral scotoma four times in a hundred examinations, and when Bjerrum's method—i.e., using small test objects at a distance of two metres—is employed, these defects are still more frequently discovered. To quote from Berry's ^ abstract of Bjerrum's article, the glaucoma field, as taken by this method, shows an interference in the function of the retina, which, whatever be the part most affected, always starts from the papilla, and pretty clearly points out that, whether from pressure or otherwise, the defect is a result of a destruction of the fibres in the papilla at the margin or sides of the excavation. In the case just described, the semi-annular defect becomes incor- porated with the darkened area on the nasal side, and evidently repre- sents a portion of a ring scotoma; indeed, in one map not here repro- duced, and taken earlier in the history of the case, this ring charactei- is more evident. The probable explanation of these ring scotomas is pressure upon the so-called intermediate fibres of the optic nerve- bundle. Although the scotoma is a large one, it may readily be understood, from an examination of the charts, that it could easily be overlooked if the visual field was investigated by one method only,—viz., by passing the test-object along each meridian from without inward, and noting the point at which it was recognized. No map is complete until the area within the boundaries of the visual field is searched with small test-objects for defects of this character, and, according to Berry, the method of Bjerrum (unfortunately not tried in this case) is more exact than the ordinary procedure. 1 Oj.hthalmic Review, April, 1890.