ART.X .-Congenital Anomalies of the Choroid

The deficiency in the choroid, known as choroidal coloboma, is generally attended with similar anomaly of the iris in the inferior portion of the eye. Coloboma generally begins in the immediate neighborhood of the optic nerve, and ends at some distance from the ciliary body. Sometimes there is also a deficiency of the ciliary body, and there may even be a furrow on the lens. Sometimes the whole eye is affected with microphthalmia. We observe, also, more or less extended colobomata, oval and exactly limited to the mucular region; they are considered as remains of the choroidal fissure.

To the ophthalmoscope, the part where the choroid is deficient gives the white reflection characteristic of the sclerotic. On this white patch we find traces of pigment and of the choroidal vessels: its border is highly pigmented.

The sclerotic at the coloboma presents an irregular ectasia. As to the retina, sometimes it also is absent, and, in place of these two membranes, viz., the choroid and retina, we find the sclerotic covers with a thin structural layer. At other times, the retina, although thin, is normal, and covers the entire extent of the ectasia, or passes over it in the form of folds.

According to one or other of these conditions, the vessels of the retina are seen with the ophthlmoscope to follow a different course; sometimes they stop when they reach the coloboma, and then proceed along its margin; sometimes they are seen to cross over the coloboma, forming at the margin of the ectasia a bend, which varies in depth with the depth of the ectasia. But again, the vessels may be in closed connection with the ectasia of the retina. Showing as many interruptions as that membrane has folds.

When the extremity of the coloboma does not extend to the optic nerve, the papilla appears in its usual form, or with a small cone, or even a small coloboma of its sheath. The papilla, oval in the horizontal diameter, can be distinguished from the coloboma only by its rose-colored tint. In a few cases, coloboma of the choroid has been found in the eyes.

Albinism, or the congenital absence of pigment in the choroid, is met with in very varying degree. The scarcer the pigment, the more distinctly do we see with the ophthalmoscope the choroidal vessels with their finer branches and the vasa vorticosa. Persons affected with albinism suffer greatly from a bright light, and therefore seek a dim one, in which they can see objects distinctly only on bringing them very near. Thus, in such cases, we have a development of myopia with a certain amount of amblyopia. The higher degrees of albinism, in which the epithelial cells and parenchyma of the choroid are almost devoid of pigment, are always accompanied with nystagmus.

This anomaly has been often observed in several members of the same family and seems to be hereditary.

We can do nothing more than relieve persons affected with albinism by prescribing blue or smoked glasses, which diminish the intensity of the light.

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