OCULAR SURFACE RECONSTRUCTION

Ocular surface disease is caused by damage, dysfunction or deficiency of any of the anatomical parts of the cornea and conjunctiva. Martin de la Presa, MD specializes in the reconstruction of the ocular surface in cases of limbal stem cell deficiency from causes such as aniridia, chemical and thermal burns, Steven-Johnson's Syndrome, contact lens related disease, graft versus host disease and other congenital disorders that affect the ocular surface.

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OCULAR SURFACE RECONSTRUCTION Q & A

What is the ocular surface?

Cornea: The transparent front part of the eye that covers the iris, pupil and anterior chamber. With the lens the cornea focuses light onto the retina providing clear vision. The cornea does not have blood vessels and receives nutrients from the tear film and the aqueous humor fluid. The cornea must remain avascular and clear for good vision. In ocular surface disease, abnormal vessels grow onto the cornea causing scarring and haze leading to significant vision loss.
Conjunctiva: This surface layer of the eye is usually transparent in color. It contains goblet cells that produce mucin, a key component to tears and necessary for allowing the tear film to be spread evenly, thus keeping the eye moist and healthy.
Limbus: This 1-2 mm area is the junction between the cornea and the conjunctiva. Limbal stem cells located here act as a barrier to prevent the vascularized conjunctiva from growing onto the clear cornea.
Eyelids: Meibomian glands in the eyelids produce lipid, a key component to tears to help reduce tear evaporation. Adequate ability to blink and to fully close the eyelids is required to keep the ocular surface healthy and lubricated.
Puncta: Tears drain to the nose by entering through the upper and lower punctum on the inner corner of the upper and lower eyelids. At times, plugs may be inserted into the puncta to improve lubrication of the ocular surface by allowing tears to remain on the eye for a longer period of time.

Ocular Surface Reconstruction: Text

TYPES OF PROCEDURES

CONJUNCTIVAL LIMBAL
AUTO-GRAFT & ALLO-GRAFT

There clock hours of limbus and conjunctiva are marked superiorly and inferiorly and the tissue is harvested from the donor eye (A,B). In the recipient, the conjunctiva is dissected free from the limbus and allowed to retract and scar tissue on the corneal surface is debrided (C). The CLAU grafts are transferred to the corresponding positions on the recipient's eye and secured with sutures and specialized tissue glue (D). In a conjunctival limbal autograft (CLAU), the donor eye is the healthy eye of the same person receiving the graft for their other unhealthy eye. In a living-related conjunctival limbal allograft (lr-CLAL), the donor eye is from a living relative that is suppling the graft for the patient's unhealthy eye.

KERATOLIMBAL ALLOGRAFT

In keratolimbal allograft (KLAL), the donor tissue is from a non-related cadaver eye. Preparation of the donor tissue involves excision of the central 7.5 mm of the cornea and cutting of the corneal scleral rim into halves (A). In the recipient eye, the conjunctiva is dissected free from the limbus and scar tissue on the corneal surface is removed (B,C). The segments of donor corneal-scleral tissue are sutured just overlying the limbus. Tissue glue secures the segments to the eye and to the conjunctival edge. This procedure ensures that there is a barrier to the invading conjunctiva.

KERATOPROSTHESIS

This device may be implanted after multiple failed penetrating keratoplasty's, stem cell transplants or in eyes at high risk for corneal transplant failure. A keratoprosthesis (K-Pro) requires some assembly prior to being sutured into position on the recipient's eye. The holes in the back plate allow nutrients to reach the donor cornea. A large contact lens that acts as a bandage is always worn to prevent the ocular surface from drying out.

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What happens before the stem cell transplant?

At the initial consultation with the transplant team, patients will be evaluated for systemic for their ability to tolerate immunosuppression by initially providing information about existing medical conditions, current medications, and family history of disease. This is followed by a physical assessment and baseline blood work. Systemic immunosuppression is required to prevent rejection of the transplanted stem cells and associated tissues. Before the scheduled transplant date, the patient must begin a regimen of immunosuppression drugs, antibiotics and antivirals to prevent infection. If applicable, relatives that are potential donors will also undergo blood tests to see if they would be suitable tissue donors.

What happens after the stem cell transplant?

Immediately after surgery, the eye will be patched and covered with a protective plastic shield for a few hours. When the eye is uncovered the patient will begin to use the eye drops prescribed. Post-operative visits typically include the day after surgery and visits at 2-3 day intervals until the ocular surface is fully healed. This may require many visits over several weeks.

The patient will require long-term close follow up to monitor for potential rejection of the transplant and to manage the eye and patient's overall well-being. Subsequent surgery may be required such as a full thickness corneal transplant.

Patients must use varying does of eye drops and systemic immunosuppression medications to avoid rejection of the transplant, to prevent infection, and to reduce inflammation. Intermittent blood tests will help monitor for adequate immunosuppression drug levels, signs of infection and adverse reactions to medications.

Why is immunosuppression so important?

Immunosuppression refers to the process of dampening the immune system to prevent the patient's body from rejecting transplant tissues, including stem cells. Rejection of the transplanted stem cells is the leading cause of failure following limbal stem cell treatment. Consequently, an individualized immunosuppression protocol based on factors inherent to the patient and the transplanted donor stem cells is followed. The immunosuppression medications used have varying levels of associated side effects so the transplant team includes the expertise of an organ transplant specialist to ensure that these drugs remains safe and effective for our patients.

What can improve the success of a transplant?

Patient compliance with using all eye drops and medications as directed is crucial to ensure success of the transplant. While rejection of the transplant can occur, with careful follow up by the transplant team and the patient's local eye care provider, the risk is significantly lowered.

Who is on the transplant team?

Many patients with ocular surface disease also have other associated eye abnormalities. Additional surgery to optimize the patient's eye pressure, eyelids or vitreoretinal health may be required. Therefore, the transplant team is multidisciplinary combining the areas of cornea, glaucoma, retina and oculoplastic surgeons. In addition, the team includes a transplant medicine specialist and a nurse coordinator that acts as a liaison with the patient's local primary care physician. Dr. de la Presa works closely with each of the members of the team to ensure optimal patient outcomes.

To learn if you’re a candidate for a limbal stem cell transplant schedule a consultation by calling the office today.

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OCULAR SURFACE RECONSTRUCTION