Corneal transplant is one of the commonest transplant procedures successfully performed by Eye doctor in Islamabad to treat irreversible corneal damage. Depending on the type of corneal pathology and part of the cornea which is damaged, the healthcare provider decides which type of corneal transplant to go for.

Read on to know more about corneal transplant and its types:

What is cornea?

The outer layer of the eye, overlying the iris, adjacent to the white of the eye is cornea. This is a transparent membrane, allowing entry of the light rays into the eye which eventually fall on the retina and form vision. Damaged cornea can become less opaque, interfering with the transmission of light, or it can change its shape, increasing pain and discomfort in the patient.

Corneal transplant is also called corneal graft or keratoplasty. This surgery can be used to improve vision, treat infection and relieve pain.

What are the types of corneal transplants performed?  

Depending on the extent of corneal damage, or part of the cornea that is damaged, the type of transplant procedure is selected. The types of corneal transplant surgeries include:

• Penetrating keratoplasty (full thickness transplant)

In this type of procedure, the damaged cornea is removed by a circular cutting instrument called trephine, from the center of the eye. Thereafter, the donated cornea is stitched in its place. Selective sutures are removed to improve vision and the remaining stitches are sometimes visible in a star-like pattern around the corners of the new cornea.

This procedure is done under local or general anesthesia depending on the preference of the operating surgeon. Most cases take only about an hour for completion, though the patient has to stay over-night in the hospital for observation.

This type of transplant is recommended when all the layers of cornea are affected by a pathology, such as stromal scarring, keratoconus, infectious corneal ulcers, combined disease of the stroma and epithelium (Peters anomaly).

The recovery time for this procedure is relatively longer than the other transplants. In addition, there are refractive errors after the surgery that can take years to correct. However, with the right care, this transplant can last for decades.

• Transplanting the front of the cornea (partial thickness transplant)

Recent developments have allowed only partial transplantation of the cornea to decrease the recovery time and risk of complications. However, this procedure is not suitable for everyone and can take longer to perform than full thickness transplant.

With partial thickness transplant, several techniques are used to perform the procedure, depending on whether the front or the back portion of the cornea needs replacement. The cutting is performed either with trephine or laser, and as with full thickness transplant, these procedures can also be performed under local or general anesthesia. The transplant is stitched into place and later selective stitches are removed.

• Anterior lamellar keratoplasty (ALK): in this procedure, only the front part or the outer part of the cornea is transplanted.

• Deep anterior lamellar keratoplasty (DALK): in this procedure, the outer and the middle layers of the cornea are removed. The remaining inner layers, i.e. patient’s own Descemet membrane and endothelium are left in place. DALK is done for: corneal stromal dystrophies, corneal scars involving partial cornea and corneal ectasias.

• Transplanting the back of the cornea (partial thickness transplant)

If the back portion of the cornea is to be transplanted, there are two options. Like anterior keratoplasty, the endothelial keratoplasty has a faster recovery and lower complication risk, as well. The difference is that the expert Best Eye Specialist in Rawalpindi uses no stitches to hold the donor cornea.  

• Descemet’s stripping endothelial keratoplasty (DSEK): in this procedure, the patient’s inner corneal layers including the Descemet’s and endothelium, as well as 20 percent of stroma, are removed and replaced with donor cornea.

• Descemet’s membrane endothelial keratoplasty (DMEK): in this procedure, the corneal inner layer of cells is replaced by donor cornea.