Coloboma of the choroid and optic nerve sheath / by Arthur H. Benson.

  • Benson, Arthur H.
Date:
1882
Catalogue details

Licence: Public Domain Mark

Credit: Coloboma of the choroid and optic nerve sheath / by Arthur H. Benson. 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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    are clear; tension is normal, and vision in the right eye is about yr^, and in the left the same. The ophthalmoscope reveals a high degree of hypermetropia—viz., four diopters in the fundus of each eye. The chorioid and retina are normal, or perhaps unduly mottled in the peri- phery ; but the appearance of the disc-region is truly remarkable. In the right eye no disc, properly so called, can be made out, but in its place a large white, irregularly depressed funnel can be seen, from the lip of which the retinal vessels seem to take origin, and over the edge of which they bend sharply, as in a glaucomatous cup. This appearance is best marked below, the superior lip not being so abruptly terminated, but gradually receding on an inclined plane from the level of the healthy fundus into the deep excavation below. Tracing the large retinal vessels we find that above they pass over the pigmented edge of the coloboma without undergoing any sudden change in direction. Following them on, they gradually get more and more indistinct until they are finally lost in the depths below. Those to the lower outer side pass suddenly from view, disappearing as over the edge of a precipice, whilst those from the lower inner side, passing over the pigmented border, Avithout change in appearance, run for a short distance and then suddenly disappear, again to become visible, but dimly, on a lower plat- form, where by their direction and size they can be recognised as con- tinuations of the above. These again bending sharply over the edge of the ledge on which they run, also disappear into the hidden depths. The area of this pigmentless disc-region is about six times the size of the normal papilla. Just below and to the inside of this disc-region, and separated from it by a narrow isthmus of fairly healthy fundus, is seen an unpigmented oval patch about one-fifth its size. This patch closely resembles in its appearance the patches seen in the eyes of the boy first mentioned. Over its surface, which is somewhat depressed below the level of the surrounding retina, several good-sized retinal blood- vessels run; its borders are slightly pigmented in places, but its surface is entirely devoid of pigment, and presents the pearly white appearance of the sclerotic. In its centre this patch shows a depression corres- ponding to a difference in refraction of three diopters as compared with the surrounding retina. Calculating, then, that four diopters of refraction correspond to one millimetre in antero-posterior measurement, we find that this inferior coloboma is depressed three-quarters of a millimetre, and the upper coloboma of the optic disc has a depression of about two millimetres in its centre, judging by the position of the fine vessels which ramify over the pearly or opalescent membrane which seems irregularly to cover its floor, leaving still deeper holes behind. This membrane is probably retinal in origin. The left eye, like the right, is strongly hypermetropic (4 D.), and the