March 30, 2015
Written by Andrew Sondag (class of 2014-2015)
My OREX day began with a delay. I had planned to meet with the ophthalmic team to watch a cornea transplant that was scheduled to begin at 8:30am, but when I arrived in the OR the doctors were just standing around. The resident explained that the donor cornea had not arrived yet, and they had to wait for it to be transported from San Francisco. After some discussion about switching tissue transport companies and about 45 minutes of waiting, the cornea finally arrived and the preparation began.
Dr. Lim, the attending, showed me the donor cornea as well as the information slip that arrived with it. She pointed out the different things you look for to make sure it is a good tissue, such as the endothelial count (which you want to be around 3,000) and time from death of the donor to extraction of the tissue. It was a bit unnerving to be reminded that this tissue came from a person who had been alive just a week before, but it also helped me remember how much of a gift this cornea truly was.
As the patient went under anesthesia, the doctors began working. The biggest difference between ophthalmologists and many of the other surgeons that work at highland is scale. As one of the ophthalmic residents put it during clinic later in the day “everything we do is small.” These ophthalmologists didn’t have large retractors or forceps; they had stools to sit on and microscopes to work over. At first I wondered if I would miss most of the action with the two doctors hovering over the patient’s eye, but one of the OR techs flipped on a monitor in a room that showed the POV of the microscope over the eye.
Two things happened to begin the surgery. The doctors inspected the eye one last time for the scarring that had been present. Dr. Lim invited me to the microscope and I was able to see it. At first I had trouble locating it, because when I think scar, I think of a discolored streak of skin. However, on an eye scarring just looks like a slight cloudiness. It doesn’t take much to alter the passage of light on what should be a clear cornea! The second thing was the cornea was measured and marked for cutting. Calipers were used to get an exact marking, proving again the point that “everything we do is small.”
The doctor’s then explained that while they were ready and scheduled to perform a full cornea transplant, they were going to attempt a tricky partial cornea transplant first. They explained that in a partial cornea transplant, only the top half of the patient’s cornea is cut away and the donor tissue is placed on top of the remaining tissue on the patient’s eye. While this leads to better outcomes, it is very technically difficult. What often ends up happening is during the cutting and separation of the patient’s cornea, the remaining tissue gets punctured. When that happens there is no choice but to perform the full cornea transplant.
The resident began the partial transplant and skillfully separated most of the top half of the cornea from the bottom half. On the monitors I could see a clear circular bubble forming between the two layers. Just as he was about to finish the separation of the layers, the bubble quickly disappeared all at once. The cornea had been punctured. This meant they had to remove the entire cornea as originally planned.
After removal of the patient’s cornea, they moved over to the donor tissue which was set up on a side table in the OR. The donor tissue comes with a lot of extra sclera attached to it, and you only need the relatively small (about 6mm diameter) cornea in the center of the tissue. To get only the tissue they needed, the resident brought out a circular punch that corresponded to the exact size of the tissue they had removed from the patient. With an unsettling but oddly satisfying *crunch*, the donor cornea was separated from the donor sclera in a perfect circle.
Now that both tissues were ready to go, all that was left was to sew the new cornea into place. You read that right, even with the eye it always comes back to needle and thread. This part of the procedure took much longer than I thought it would. Almost half of the entire operation was dedicated to sewing the cornea into place. Part of the reason for this is making sure that the cornea isn’t stretched too tight or too loose. Either of which could cause problems down the road. After over an hour of stitching, the doctors showed me how they tested the seal. They mixed a dye and poured it over the eye. If any of the dye appeared on the other side of the cornea, they would know they had a bad seal. Amazingly, none of the dye made its way past the stitches that locked the new cornea into place!
With that test completed the surgery was done, and I had witnessed my first full cornea transplant. I had so much fun with the ophthalmic team that after lunch I stayed with them to shadow clinic hours, where they explained a lot of the more simple procedures they do in the office (again all with a microscope!). I would definitely recommend picking an eye surgery next time you are staring at that white board deciding what to watch. It is definitely an interesting contrast between some of the “large” surgeries that many of the other surgeons are performing.