Page:Handbook of Ophthalmology (3rd edition).djvu/307

Rh chamber, Roser has proposed for this condition the very suitable name of "hypopion keratitis."

The beginning of this affection is always near the centre and in the deeper layers of the cornea. At that place there appears a round, circumscribed, gray opacity, in which, when examined with a magnifying lens and by focal illumination, a number of short gray striæ may be detected. They may be either parallel with one another or radiating. The superficial layers of the cornea are at the same time diffusely clouded, and there are many small defects and irregularities in the epithelial covering.

The infiltration of the deeper layers now assumes gradually a yellowish purulent color, while a loss of substance occurs upon the surface. The appearance of these superficial ulcers is very varied. Often the ulcer is no larger than the purulent infiltration, has the appearance of a so-called corneal facet, with a smooth, glistening floor, clean margins, and no steep walls, exactly as if a piece had been sliced from the cornea by a single cut with a sharp knife. It is very easy to conceive, under these circumstances, that by the collapse of an abscess the anterior surface of the cornea has sunk in. The possibility of such a process, as described by Arlt, cannot be questioned, but, as a general rule, this change of form seems to be due to a superficial disintegration of tissue.

In other cases the superficial ulcer attains soon a greater size than the purulent infiltration behind it; its margins are sometimes flat, sometimes steep, and are often quite clean, that is, free from any purulent infiltration; it is then sometimes not easy to recognize the full extent of the loss of substance.

Frequently there is some punctated purulent infiltration in the corneal substance surrounding the margin of the ulcer.

The further course and the entire type of the disease depend essentially upon whether the deep purulent infiltration or the superficial ulcer becomes more extensive. Cases of the first kind are called corneal abscesses, on account of the circumscribed accumulation of pus in the tissue of the cornea. Unless recovery is rapid, the enlargement of the abscess and of the superficial ulcer causes extensive destruction of tissue.

Other cases assume a dangerous character, less from the puru-