Technique of Eye DissectionsWoll, Frederic A. (Frederic Albert)
Science
Technique of Eye Dissections
Woll, Frederic A. (Frederic Albert)
Dissection; Eye -- Surgery
The anterior half will show the lens _in situ_, the ciliary processes,
the posterior aspects of the iris and the lens, the corona ciliaris, the
orbicularis ciliaris, and the ora serrata. (Fig. 16.) If the eye has
been cut in two too far forward of its equator, the ora serrata will not
be present. The ciliary processes and posterior aspect of the lens may
be seen to better advantage when the anterior half of the vitreous is
removed. This is done with the dull-pointed tweezers, by catching hold
of the vitreous at any part of its free or cut margin, and stripping it
off both the ciliary processes and the lens, using a prying, pulling
movement to do so. (Fig. 17.) The two layers of the pigment cells, pars
ciliaris retinae, which cover the inner surface of the processes, may
be removed by picking them away carefully with the tweezers. The
processes then will be seen to be a whitish color. The pupillary edge of
the iris rests upon the capsule of the lens, but the nearer the approach
is to the choroidal edge the farther the iris is from the lens; thus are
formed the anterior and the posterior chambers of the eye. The
dissection of the sagittal section of the eye, explained further on,
will show these two chambers in section. One will gain a much clearer
conception of their construction in that section than in the “anterior
half” specimen.
[Illustration: Fig. 17--Anterior half, showing how to pull off vitreous.
(Page 49.)]
Now, remove the lens, using the point of the scalpel to cut through the
suspensory ligament close to the lens. When this has been done there
will be seen in the anterior chamber a thin, watery liquid--the aqueous
humor.
The corona ciliaris and orbicularis ciliaris may be better seen and
studied if viewed through a hand lens.
THE IRIS
To see the iris, take hold of the cut edge of the choroid, and, gently
pulling, separate it from its attachment to the corneo-scleral junction.
The white ring on the anterior surface of this part of the second coat
of the eye is the ciliary ring. With a scissors, cut around this ciliary
ring at its outer edge. This specimen will show the anterior surface of
the iris, and on the posterior side it will show the close relationship
between the iris and the ciliary processes. A hand lens will help
greatly to bring out the very interesting fine points.
THE CORNEA
After the anterior portion has had everything removed from it there will
be left nothing but the first coat or tunic of the eye--the anterior
portion of the sclerotic and the cornea. The way the cornea seems to fit
into the sclerotic is not quite as one is led to believe when told that
it fits into the sclerotic much the same way in which a watch crystal
fits into a watch.[3] Holding this part of the eye up to a strong light
one will see that the sclerotic seems to overlap the cornea in the
vertical axis.
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