Corneal Transplants

Corneal transplant surgery is sometimes the only option for the restoration of vision in an otherwise blind eye. The most common reason for this procedure is corneal decompensation after a cataract surgery. The next most common reasons include congenital abnormalities of the cornea, corneal scars, corneal ulceration, Fuchs’ Endothelial Dystrophy, herpes simplex, keratoconus, and varicella zoster viral opacifications (the development of cloudiness or becoming opaque).

The Corneal Transplantation Procedure

During the complete preoperative evaluation required before surgery is scheduled, Dr. Singh makes every attempt possible to confirm retinal and optic nerve function. Avoiding any unnecessary surgery is quite a priority at Eye Specialists of Houston. In addition, a careful examination will determine which type of cornel transplantation is best suited your cornea, thereby maximizing visual recovery and minimizing potential post-operative issues such as astigmatism and rejection.

While the majority of adult patients will have this surgery with the assistance of local anesthesia, general anesthesia is frequently required for children as well as anxious or uncooperative patients.

After the administration of anesthesia, Dr. Singh measure and mark the patient’s cornea to determine the amount to be excised and replaced with donor corneal tissue. Careful preparation for the specialized cornel transplant surgery includes preparation of the donor cornea. A corneal trephine is utilized. This is a surgical instrument designed to maintain a specific relationship to the cornea in order to remove the precise circular area of the cornea needed.

The cornea being replaced (whether diseased or scarred) is removed via the same specialized medical procedure.

The donor cornea is then gently sewn into place with a very high level of skill by means of ultra-fine sutures that are the approximate size of only one-third the thickness of human hair.

Corneal transplantation is sometimes combined with other procedures, most frequently a cataract extraction with an intraocular lens implantation or placement of a secondary intraocular lens in those patients who have previously had cataract surgery but did not receive a lens. Additionally, any other necessary anterior segment procedure (such as removal of adhesions, removal of vitreous and repair of iris abnormalities) is performed.

Patients can expect a very gradual recovery of their vision. The post-operative phase requires patients to have patience because, while vision may improve immediately after surgery, the best vision obtained may not be reached for as much as 12 months (sometimes more) following the surgery. The rate and extent to which the vision recovers depends on many factors, including which type of corneal transplant is performed and the patient’s other ocular comorbidities.

Dr. Singh may elect to remove some sutures from the cornea within just a few months after surgery. The removal of sutures is very often performed to help alleviate astigmatism. Dr. Singh makes the decision once the cornea shows signs of being held in place securely.

Penetrating Keratoplasty (PK)

Penetrating keratoplasty is the original approved corneal transplantation surgical method; and, it remains the most common method (dating back over 100 years). Until recently, the majority of all corneal transplants in the United States were PK procedures.

A full-thickness (generally 7.0 mm – 8.5 mm diameter) corneal button is transplanted into the patient’s eye with the aid of an operating microscope and very fine 11.0 microfilament sutures.

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Ulcerated Cornea Before PK Surgery by Dr. Gurpreet Singh

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Same Cornea After PK Surgery by Dr. Gurpreet Singh

Deep Anterior Lamellar Corneal Transplant (DALK)

Lamellar keratoplasty is a surgical procedure in which only a layer in the front of the patient’s cornea (anterior) is removed and replaced. In this manner, the anterior chamber of the cornea remains intact.

By not transplanting the subsequent endothelial layer of the cornea it is hoped to reduce the risk of rejection of the cornea. Additionally, visual rehabilitation may occur more rapidly and the long-term success of the cornea is increased.

Dr. Singh is one of only a few corneal transplant surgeons routinely performing this technique, and the 1st surgeon on Houston to perform a variant of his technique known as the maximal depth (or Big Bubble) technique. This variant technique achieves a smoother interface and ~ visual potential is increased.

Deep Anterior Lamellar Keratoplasty is suitable only for those patients with a corneal disease that involves only the anterior or stromal portion of the cornea. Examples of corneal diseases that may be amenable to DALK include keratoconus and corneal scars. Dr. Singh will determine if this is a suitable alternative through a thorough and careful examination.

Endothelial Corneal Transplant (DSAEK)

This is an exciting advance for individuals with diseased corneas due to edema that has fairly recently become available.

Trough endothelial keratoplasty, the healthy anterior part of a patient’s cornea is retained while their diseased corneal endothelium is replaced with healthy donor tissue through a small incision. No sutures are needed in this procedure to hold the donor cornea is place, and only a few sutures are placed at the surgical incisions. These sutures are generally removed much earlier than with o her corneal transplantation techniques, most often from 2 to 6 weeks after the surgery.

One of the exciting aspects to this new surgical procedure, and there are several, is that the recipient’s cornea remains structurally intact and resistant to injury. Additionally, the visual rehabilitation is much faster and occurs in 2 to 3 months as compared to 12 to 18 months for traditional PK.

Certain patients may qualify for a Endothelial Keratoplasty (DSAEK), particularly those who have corneal edema due to defective corneal pump {endothelial) cells. Corneal decompensation after cataract surgery and Fuchs’ Endothelial Dystrophy are the most common circumstance that may qualify for an endothelial transplantation. A comprehensive examination of the cornea by Df. Singh is necessary to determine if thls procedure is an appropriate alternative for the patient to traditional corneal transplantation.

Returning to normal activities within 1 week following this particular surgery is not uncommon.

Artificial (Synthetic) Corneal Transplant

An artificial corneal transplant is a technique used to rehabilitate those patients who have previously undergone a penetrating keratoplasty (PK), but whose corneal transplant has failed and the prognosis for another corneal transplant is poor. These include conditions such as a severely vascularized cornea where the chance of rejection is high or in those patients who have previously had 2 or more corneal transplants where rejection was experienced.

This technique involves securing a plastic, inert disc on a carrier donor cornea that is then sewn onto the patient’s cornea after the previous damaged tissue is removed. This surgery can be highly successful, and may be the only reasonable alternative for patients who are poor candidates for further successful corneal transplantations. This condition requires more care by the patient postoperatively, but may allow for a more rapid visual recovery.

If you have had a poor outcome f:rom previous corneal transplantation, Dr, Singh can evaluate your candidacy for this new and exciting procedure through a thorough preoperative examination and discussion.

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Artificial or Synthetic Corneal Transplant