Partial Corneal Transplant: Types, Indications & Benefits

Corneal transplantation has advanced significantly. Treating corneal disease is no longer the obstacle it once was, and although donor tissue was historically limited, partial corneal transplant techniques now allow a single donor cornea to benefit more than one patient. The patient no longer needs a full-thickness corneal replacement — only the damaged layer of the cornea is replaced. This article explains what a partial corneal transplant is, the different techniques available, and when each is used. Read on for everything you need to know.

First, What Is Corneal Transplantation?

As covered in earlier articles, corneal transplantation — also known as keratoplasty — is a surgical procedure in which a damaged cornea is removed and replaced with healthy donor tissue from someone who has chosen to donate their corneas after death.

What Are the Types of Corneal Transplant?

Originally, corneal transplant surgery was very complex. The full cornea had to be replaced regardless of whether the entire cornea or only certain layers were diseased — and this also contributed to a chronic shortage of donor tissue. That picture has changed today, as we'll explain below.

Corneal transplants are broadly divided into two categories: full-thickness (penetrating) and partial-thickness (lamellar).

1. Penetrating Keratoplasty (Full-Thickness Transplant)

This procedure is also known as a full-thickness corneal transplant and abbreviated as PK (PKP).

In PKP, all layers of the cornea are replaced. The surgeon uses either a manual trephine or a femtosecond laser to remove a small, circular section of the cornea and replace it with a matching-thickness disc of donor tissue. Historically, this was the most common type of corneal transplant.

2. Partial Corneal Transplant (Lamellar Keratoplasty)

There are two main categories of partial corneal transplant.

Type 1: Anterior Lamellar Keratoplasty (ALK)

In this procedure, the diseased tissue from the front layers of the cornea (epithelium and stroma) is removed, while the back endothelial layer is left intact. There are two main techniques.

The first is also known as Superficial Anterior Lamellar Keratoplasty (SALK).

In SALK, only the most superficial layer of the cornea is replaced. The stroma and endothelium remain in place.

The second technique is Deep Anterior Lamellar Keratoplasty (DALK).

Surgeons use DALK when the corneal damage extends into deeper layers.

In both techniques, the right approach is selected based on the patient's specific case.

Lamellar keratoplasty is gentler on the eye than penetrating keratoplasty. The patient generally faces a lower risk of graft rejection and fewer complications. Recovery is also more comfortable, and visual rehabilitation is faster.

Type 2: Endothelial Keratoplasty (EK)

Most patients who need a corneal transplant have damage that primarily affects the deepest layer of the cornea — the endothelium. This category of transplant is divided into two techniques.

Type 2a: Descemet's Stripping Endothelial Keratoplasty (DSEK / DSAEK)

This is the most common form of endothelial keratoplasty. Healthy donor tissue replaces about one-third of the corneal thickness.

In this procedure, the diseased endothelium is removed along with a layer of Descemet's membrane (the tissue that supports the corneal endothelium). The outer corneal tissue remains intact. DSAEK is the most common form of endothelial keratoplasty.

The second technique is Descemet's Membrane Endothelial Keratoplasty (DMEK).

In DMEK, an even thinner layer of donor tissue is used — the endothelium and Descemet's membrane only.

DMEK is one of the most precise corneal transplant techniques available.

In both techniques, the right approach is selected based on the patient's specific case.

The Right Surgeon for DMEK

Dr. Ahmed Shaarawy is among the most experienced surgeons in Egypt for DMEK, having been the first to perform the procedure locally. He is a Lecturer and Consultant of Cornea and Refractive Surgery at the Research Institute of Ophthalmology, with a PhD and a fellowship in cornea from Legacy Devers Eye Institute in Oregon, USA. There he trained under leading American cornea surgeons and was the first to perform DMEK in Egypt using the S-Stamp technique.

He has helped train many other surgeons in this technique and has presented on it at conferences across the United States and the Arab region. With a long record of successful surgeries and consistent adoption of the latest cornea techniques, Dr. Ahmed Shaarawy is regarded as one of Egypt's leading ophthalmologists.

Advantages of Partial Corneal Transplant

Partial corneal transplantation helps in several ways, including:

• Fewer complications
• Lower risk of induced astigmatism
• A lower rate of graft rejection compared to full-thickness transplant
• Faster recovery
• One donor cornea can benefit multiple recipients

Risks of Corneal Transplantation

Patients should understand that the donor cornea is foreign tissue, so the body may attempt to reject it. Rejection or related issues may present as:

• Eye infection
• Corneal inflammation or ulceration
• Cataract
• Elevated intraocular pressure

Most of these complications can be managed effectively if detected early.

Your eyes are your most valuable sense. Don't hesitate to take the step toward a corneal transplant if you need one — clear vision is what allows you to enjoy the world around you.

For more information about corneal transplantation, you can read this article.