Page:Plates illustrating the natural and morbid changes of the human eye.djvu/30

24 semiopaque " retina." A thin unequally dilated blood-vessel of the retina is seen passing across the figure near the lower third.

Figs. 18, 19, 20 represent an advanced stage of what is termed Retinitis pigmentosa.

Fig. 21.

Myopia, "short sight." (From the right eye of a person with blue irides.)

The optic disc and the retina, choroid, and sclerotic immediately adjoining it.

The optic disc near the middle of the figure is oval-shaped, the long axis of the oval being vertical. The centre of the optic disc is whitish, the rest pink. The disc is completely, surrounded by a white figure. (This figure has in most Myopics a crescentic shape, and is termed the "crescent," or "crescentic atrophy." It generally skirts that margin of the optic disc which lies nearest the yellow spot.)

The largest portion of the white figure lies on the side nearest the yellow spot; a narrow rim of white also intervenes between the rest of the margin of the optic disc and the vascular choroid. The choroid adjoining the crescent appears pale red, it is slightly atrophic, and gradually goes over into healthy choroid. The blood-vessels of the retina are normal as regards size and number. Those which pass over the white figure follow the abnormal curvature of the tunics; they appear to bend forwards towards the vitreous chamber, where they pass from the "white" on to the "red" portion of the figure.

Fig. 22.

Myopia. Right eye of a person with brown irides.

The optic disc with a small portion of the retina, choroid, and sclerotic adjoining it.

The optic disc has a pink colour, and appears oval-shaped, with the long axis of the oval vertical. The white figure which surrounds the optic disc has not a crescentic but an irregular shape, as is often observed in extreme myopia.

The brown line which skirts the greater part of the white figure, is