Every surgical technique has a set of nuances and complexities that should be followed, adequately memorized, duplicated and re-duplicated during the surgical procedure. Pre-Descemet’s endothelial keratoplasty is a form of endothelial keratoplasty that has many surgical steps resembling Descemet’s membrane endothelial keratoplasty, although the major difference is in the way the tissue donor graft is harvested.
Apart from the Descemet’s membrane-endothelium complex, the pre-Descemet’s layer also forms the essential component of the tissue donor graft. The tissue donor graft is harvested by injecting air from an air-filled 5 mL syringe that is introduced from the sclerocorneal rim with the endothelial side up. A type 1 bubble is formed; it typically spreads from the center to the periphery and is approximately 8 mm wide. The periphery of the bubble is ruptured with a side-port blade, and trypan blue is injected to stain the graft. The graft is obtained by cutting the bubble all around the periphery and is then placed in storage media.
The surgical procedure of donor graft insertion in the recipient eye can be summarized in 15 steps, which are described below. The video has been contributed by Dr. Amar Agarwal for this blog.
1. Fix the trocar anterior chamber maintainer (T-ACM), or even a routine anterior chamber maintainer (ACM) can be fixed if the surgeon is not well versed with the use of a T-ACM.
2. Connect the T-ACM to the air pump. This facilitates continuous air infusion into the eye.
3. Two side-port incisions are made at the superotemporal and superonasal positions.
4. Descemetorhexis is performed with a reverse Sinskey hook.
5. A 2.8-mm clear corneal incision is made to remove the scored Descemet’s membrane-endothelium complex
6. Inferior iridectomy is performed with a vitrector.
7. Load the PDEK graft in an IOL injector.
8. Switch off the air pump.
9. Inject the PDEK graft in the anterior chamber. If the anterior chamber is shallow, then the assistant can inject a bit of fluid in the anterior chamber from the side-port incision.
10. Suture the clear corneal incision.
11. Check the correct orientation of the graft. An endo-illuminator can be used to facilitate this.
12. Unroll the graft and inject a bit of air beneath the graft.
13. Switch on the air pump connected to the T-ACM.
14. Unroll the graft fully using a reverse Sinskey hook and center it properly.
15. Suture the wounds and remove the T-ACM.