Fig. 56—Showing method of gathering up the extrinsic tissues in order to get rid of the pucker in the cornea.
The pupil will now have been made square, and so large that no difficulty will be experienced in reflecting either light into the eye, or in examining the inside of the eye. Care must be taken not to lacerate the anterior surface of the lens when the iris is drawn back by the pins.
Putting the pins into the cornea, and using them as levers with the point of entrance in the cornea as a fulcrum, will pucker the cornea considerably, and a good clear fundus cannot be obtained. This is easily overcome. Simply gather up all the tissues surrounding the eye, force them backward, and hold them firmly with the fingers of the left hand. ([Fig. 56].) The right hand is then free to handle the skiascope or ophthalmoscope, so that the interior of the eye may be thoroughly examined.
Another way to prepare an eye for ophthalmoscopic examination is as follows: Go to a slaughter house and procure a beef eye from an animal that has been killed but a few minutes previously. Placing the eye immediately into an 8 per cent. solution of cocaine and leaving it there for about an hour will dilate the pupil to such an extent that work with the ophthalmoscope will be made very easy. This, as indicated, can be done only with an eye that is very fresh.
Fig. 57—Showing window cut in sclerotic, choroid, and retina.
Still another way to see the interior is to cut out a piece of the sclerotic about the size of a twenty-five-cent piece; then pinch up and tear out the choroid and the retina under the opening made in the sclerotic. ([Fig. 57].) Hold the eye, the cornea forward, close to a bright light, and the image of the light will be seen upon the retina. The closer the light is to the eye, the greater the illumination will be in the interior of the eye. If the opening or “window” is close enough to the optic nerve, the optic papilla can be seen easily. And, if care has been taken to have the opening made midway between the two branches of the retinal artery, the entire course may be followed. The direction of the retinal artery can be determined by ophthalmoscopic examination.
THE LACRIMAL DUCTS
To find the lacrimal ducts, cut across the outer and inner canthi of the enucleated eye, pushing the eye forward and the lids backward. That will expose the conjunctiva of both eyelids and eye, and also show the conjunctival fornices. On the upper surface of the palpebral conjunctiva, and near the outer canthus, will be seen, upon close inspection, a number of minute openings, usually eight. These are the openings of the lacrimal ducts. Pins or straw that have been lubricated with vaseline, may be inserted and pushed into these openings for a considerable distance, and the course of the ducts then can be traced easily. ([Fig. 58].)