Observations on the structure of the central fovea of the human eye / C. H. Golding Bird and E. A. Schäfer.

  • Golding-Bird, C. H. (Cuthbert Hilton), 1848-1939.
Date:
[1895]
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the structure of the central fovea of the human eye / C. H. Golding Bird and E. A. Schäfer. 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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    Miiller gives no figure of the fovea in man, but in another paper1) he describes and figures the structure of the same part in the chame- leon and from this and the comparisons which he draws between the two it is clear that he fully recognises the many points of similarity which they exhibit. In the figure of the chameleon's fovea a dipping inwards of the membrana limitans externa which is covered by long slender cones, is distinctly represented; and the cone-nuclei are shown to be here removed from the limitans externa instead of being closely applied to that membrane as is the case over the rest of the retina. The measurements given by Miiller would give the human fovea the form of a small horizontally extended pit with steep sides, some- what like the figures given by Hulke and Krause (see fig. 2). Henle*) figures a broadly open fovea which he states to be only 0-2 mm. diameter but calculated from the magnification of the figure it must be at least double this. He gives the thickness in the middle as about 0-1 mm. but the figure again represents it as somewhat greater (0123 mm. without the pigment layer). There is no distinct depres- sion of the external limiting membrane. The retinal elements are evidently so ill-preserved as to render it extremely difficult to deter- mine their relations at this part. Hulke gives a description of the yellow spot and central fovea which is in many respects different from that of H. Miiller. He figures the fovea as a deep pit with steep sides terminating in a point, oppo- site the very middle of which there are no recognisable retinal elements except the cones; this most central part is however quite narrow, almost linear, and the retinal layers with the exception of the nerve- fibre layer are all represented as extending quite up to the centre. The limitans externa is a plane, without any depression, the cones opposite the centre of the fovea are not delineated as Longer than elsewhere in the macula; the cone-nuclei are absent oppose he very middle of the fovea, which appears occupied below the cone! by a blending of the inner granules and ganglion cells. Near the Twtoburger naturwissenschaftliche Zeitschrift. 1862 ^ EL «) Handbuch der system. Anatomie. 1366. - E.ngeweulelelne. E>lg.51«i. p.b« :1) Phil. Trans. 1867.