Disturbances of the visual functions / by W. Lohmann ; translated by Angus Macnab.

  • Lohmann, W.
Date:
1913
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Licence: In copyright

Credit: Disturbances of the visual functions / by W. Lohmann ; translated by Angus Macnab. 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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    at least, even though such a variation be present and a scotoma occur of acquired origin from damage to the retinal elements, or to a lowered central visual efticiency, this has nov^eight in a discussion on the slight blunting of sensibility which may occur in places in a normally developed eye. Whether in fact this distinction of a scotoma resulting from damage or defective development of the central area of the retina can be maintained, is a question v^hich must be decided by comparative investigations into visual acuity and intensity of the scotoma, on the one hand when pathological changes have occurred, and on the other, in congenital cases. Naturally the visual acuity and the scotomata must not be un- reservedly held to be parallel phenomona, particularly in congenital amblyopia; on the contrary, careful attention must be paid to a defect in the field and the visual acuity at exactly the same spot. For it is possible that we may have a central scotoma not coincid- ing with that portion of the retina which, on account of its visual superiority, is actually used for vision, and which would naturally be tested in estimating any visual defect. In Heine's cases an association was established between the visual acuity and the extent and intensity of the interference with the field. In the following table I have recorded in percentages Heine's results :— \1SUA], ACl lTV Scotoma demons'irated in V.o. ■= None Relative for colour Absolute for colour Relative for white Absolute for white i 1 3 .1 1 To i To < -'n Per cent. 28-4 12-4 12-5 9-0 5-8 Per cent. 63-9 49-6 9 0 5-8 Per cent. 34-8 29-0 Per cent. 37-5 45-0 17-4 8-7 Per cent. 7-1 37-2 50 0 36-0 34-8 CO-9 Cause of Congenital Amblyopia.—At present we are only able to advance conjectures as to the origin of congenital amblyopia, we know of no anatomical basis for the condition. Heine examined the optic nerve of an eye with typical congenital amblyopia, and the result was negative ; as to the condition of the retina no trust- worthy findings were obtained. Naumoff ^ and voN Hippel - thought that the cause might be sought for in inter-partum macular haemorrliage. We must note, however, that such an origin would involve permanent changes visible w'ith the ophthalmoscope (Uhthoff). The rarity of binocular amblyopia, although bilateral inter-partum haemorrhages are by no means so rare,^ is in direct opposition to the traumatic hypothesis for the origin of congenital amblyopia—that damage and injury to the optic nerve-fibres are ^ Arch. f. 0];)hthal., xxxvi. - Ibid., xlv. ^ V. SiCHEKER : Bericht der Heidelberger Gesellscliaft fiir Ophthalmogie, 1907.