These are largely in use in the human being, and have been employed in
the lower animals in different cases, especially in the horse, with
excellent effect. The advantages may be summed up in this, that they do
away with the unsightly appearance of an empty orbit with the edges of
the lids turned into the dark aperture, enhance the value by restoring
the face to nearly the natural appearance, and prevent the lodgment of
dust and insects in the cavity.
The artificial eye may be made to appear more natural if made of glass,
yet when made of horn or still better of hard rubber, colored like the
normal iris and pupil, it has the advantage of greater lightness. It
must be perfectly smooth so as to cause no discomfort, and should never
be introduced so long as there is any irritation in the stump or
conjunctiva. It may be slipped in like a button, first beneath the
deeper upper lid, and then beneath the lower, and should be worn only
while at work and so long as it causes no irritation nor purulent
discharge. On the return of the animal to the stable, the artificial eye
is taken out, washed and placed in clean pure water. The orbit should be
sponged out with a weak collyrium (boric acid 1 ∶ 100).
In man, excentration is sometimes substituted for enucleation, the
cornea is removed together with the lens, vitreous, choroid and retina,
leaving only the sclera which contracts into a dense scar tissue with
the muscles attached. Or an artificial vitreous of glass or unoxidizable
metal is introduced around which the sclera is allowed to heal. This
introduces an additional element of danger over the formation of a
simple sclerotic stump, but, when successful, it affords a better
support to the artificial eye, turning it freely in harmony with its
fellow and giving it a more natural aspect.