Page:Plates illustrating the natural and morbid changes of the human eye.djvu/27

Rh and enlarged. Near the seat of inflammation appears the retina oedematous; its transparency is slightly impaired.

To the right of the optic disc, at the margin of the figure, are seen the inflamed retina and choroid (more fully represented on Plate VI. Fig. 12).

Fig. 14. The region of the yellow spot, represented in a later stage of the form of inflammation, shown in Eigs. 12, 13.

Near the middle of the figure are represented groups of black pigment molecules. The brilliant yellowish- white and opaque portion beneath and round these is a portion of choroid and retina altered by inflammation.

Dissection showed that the yellowish reflection was in this instance caused, not by the sclerotic, viewed through transparent and atrophic choroid, but by the choroid and retina ; these had become changed into a thick yellowish-white and opaque substance.

Two blood-vessels of the retina are represented passing across the figure. The one, which is unequally dilated and tortuous, runs in the altered portion of the retina itself.

Fig. 15. Extreme hyperæmia of the optic disc. (This is the fellow disc to the one shown in Eigs. 16, 17.)

A narrow rim of the tunics is represented adjoining the disc.

In the centre of the optic disc we observe a black spot, surrounded by a small white one. The latter is an appearance often observed in healthy eyes, and is caused by white connective tissue, which surrounds the large blood-vessels, and separates them from the bundles of optic nerve fibres. The black spot is supposed to be a peculiarity produced by reflection of the light.

This optic disc appears almost as red as the adjoining choroid. It is normal as regards the shape and the transparency of the optic nerve fibres and the vessels of the retina.