Transplantation procedure new step in evolution of endothelial keratoplasty

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Pre-Descemet’s endothelial keratoplasty is a new corneal transplantation technique using a graft consisting of the pre-Descemet’s layer (Dua’s layer), Descemet’s membrane, and endothelium.

By Cheryl Guttman Krader; Reviewed by Amar Agarwal, MD and Priya Narang, MS

Chennai, India-Pre-Descemet’s endothelial keratoplasty (PDEK) is a new corneal transplantation technique that is expected to offer the visual recovery benefits of Descemet’s membrane endothelial keratoplasty, but with advantages of easier tissue handling and expanded donor availability, according to Amar Agarwal, MD, and Harminder Dua, MD, who developed it.

The procedure involves transplantation of a graft consisting of endothelium, Descemet’s membrane, and the pre-Descemet’s layer (PDL)-also named Dua’s layer after Harminder Dua, MD, who discovered the sixth layer of the cornea between the stroma and Descemet’s membrane.

Since Dua’s layer is more fibrous than Descemet’s membrane, it adds rigidity to the graft, which limits scrolling and thus facilitates intraoperative handling and manipulation. In addition, a PDEK graft may be harvested from donors of any age, unlike DMEK grafts for which only eyes from donors aged 50 and above are considered suitable based on endothelial cell density.

Background on procedure

Dr. Agarwal, chairman and managing director, Dr. Agarwal’s Group of Eye Hospitals, performed the first PDEK case in September at his Hospital in Chennai, India. The patient was a 64-year-old man with pseudophakic bullous keratopathy. On the first day after surgery, the patient had a clear graft, and he achieved rapid visual recovery with BCVA of 20/30 after 3 weeks.

By mid-February, Dr. Agarwal had performed 45 PDEK procedures with similarly good early results.

“Now, data from ongoing follow-up is needed to determine rates of endothelial cell loss, graft detachment, graft failure, visual acuity, and visual quality over the long-term,” said Dr. Agarwal.

About PDEK

Procurement of the PDEK graft is performed with the donor corneal scleral button positioned endothelial side up. Using a 30-gauge needle introduced from the limbus into the mid-peripheral stroma (Figure 1A), air is injected between the PDL and posterior stroma in order to create a type 1 big bubble (Figure 1B).

Trephination is performed (Figure 1C) around the margins of the big bubble (diameter of about 8 mm). After injecting trypan blue into the big bubble (Figure 1D) to stain the Descemet’s membrane, the donor button is dissected with corneoscleral scissors (Figure 1E) and stored in MK medium while waiting insertion into the host eye (Figure 1F).

The epithelium of the recipient eye (Figure 2A) is removed to aid visualization. After marking the cornea with a trephine, the anterior chamber is entered with a knife, trypan blue is injected to stain the Descemet’s membrane and then excess dye is washed from the anterior chamber. The margin of the Descemet’s membrane that will be removed is first scored and then stripped from the endothelial side using a reverse Sinskey hook (Figure 2 B). After the peeled Descemet’s membrane is removed from the eye (Figure 2C), the PDEK graft is inserted using a specialized injection system that is an IOL injector minus the spring.

The graft is injected with the rolled up margins of the graft towards the cornea (Figure 2D), and then the entry site is sutured to prevent the graft from slipping out. Unrolling of the graft is achieved with slow injection of air and fluid beneath the graft (Figure 2E) while stroking the corneal surface over the graft.

Once the graft is unrolled, air is injected into the anterior chamber to achieve its firm adhesion to the Descemet’s bed of the recipient eye (Figure 2F).

Amar Agarwal, MD

E: aehl19c@gmail.com

Dr. Agarwal has no financial interest in the subject matter.

Priya Narang, MS

E: narangpriya19@gmail.com

Dr. Narang has no financial interest in the subject matter.

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