Page:Plates illustrating the natural and morbid changes of the human eye.djvu/23

Rh grey-blue halo, adjoining it, is the region of the yellow spot (this halo is represented too light in the figure).

PLATE VI. Fig. 7. Anæmia of the optic disc and of the retina, with traces of atrophy in the choroid, near the margin of the optic disc.

The round optic disc occupies the centre of the figure. The middle of the disc appears white, being occupied by fibrous tissue only, the rest bluish-white and opaque ; this colour is the conjoint effect of transparent optic nerve fibres, and of semiopaque connective tissue.

The retinal veins and arteries, in the transparent retina, as well as in the optic disc, are extremely thin, and appear less numerous than in health.

In the choroid, to the right of the optic disc, is a yellowish opaque irregular patch, which is probably the result of atrophy of a circumscribed portion of choroid. The choroid has a pale red colour throughout; this, considering the diminished blood supply to the retina and the less saturated pigment of the choroid, may be attributed to anaemia of the choroid.

(Anæmia of the optic disc, and of the tunics, has been observed in both eyes after great loss of blood.)

Fig. 8. Anæmia and atrophy of the optic disc, and slight ancemia of the retina.

Left eye. The optic disc and the tunics immediately adjoining it.

The optic disc, situated in the middle of the figure, appears white in the centre (which is occupied by connective tissue only); the rest of the disc is bluish-white and opaque. The disc is surrounded by a somewhat irregular white rim of sclerotic (the inner edge of the sclerotic aperture). The disc, as to colour, resembles the one observed in chronic glaucoma (see Plate IX. Tig. 29), but differs from it in the complete absence of signs of pressure in the retinal vessels in its area.

An extremely thin retinal artery, and a comparatively large number of irregularly-dilated retinal veins, pass through the optic disc. (It may