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Surgeons explain different uses of oral mucosal grafts
Lid margin reconstruction and treatment of total limbal stem cell deficiency are described.
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The ocular surface plays an important role in the overall health and visual quality of the eye, and as such, any compromise of the ocular surface can often contribute to secondary visual compromise and result in symptoms that may negatively affect the patient’s quality of life. An important player in the ocular surface scene is the band of stem cells located at the ocular limbus. When disease processes or other etiologies damage these cells, the surrounding conjunctiva can invade the cornea and result in potential visual degradation.
Conjunctiva lines the ocular surface, fornix and inner lid surfaces, and when conjunctival tissue is lost, it needs to be replaced. Preserved human amniotic membrane has been an acceptable tissue replacement in many of these situations. Although autologous cultivated oral mucosal epithelial cell transplantation has shown promising results in ocular surface reconstruction, oral mucosal grafts are yet another source of tissue replacement on the ocular surface as a surrogate to treat limbal stem cell deficiency.
Oral mucosal epithelium, a non- keratinized stratified squamous avascular epithelium, is supported by a dense collagenous layer of lamina propria. Oral mucosal graft serving as a free graft for ocular surface reconstruction offers several advantages, such as easy tissue access and tissue harvesting, excellent tissue properties, adequate tissue availability, and complementary immunological properties, and it often resists contracture formation and integrates well to a moist ocular surface environment. These features make it a good alternative tissue source for ocular surface reconstruction.
In this column, Drs. Cheng, Sheha and Tseng describe two surgical techniques for oral mucosal grafting for ocular surface diseases.
Thomas “TJ” John, MD
OSN Surgical Maneuvers Editor
Oral mucosal graft is a well-known standard surgical procedure for ocular surface, eyelid and orbital reconstruction. Oral mucosal graft is an easily accessible autograft that can be harvested in a sufficient size for single or multiple procedures. It is a stable source of stem cells that minimizes the need for allografts with the subsequent indefinite use of immunosuppression.
Patients with severe ocular surface involvement, such as Stevens-Johnson syndrome, chemical burns, ocular cicatricial pemphigoid and profound dry eye syndrome, usually develop lid margin keratinization and limbal stem cell deficiency with subsequent persistent epithelial defects, corneal vascularization, scarring and blindness. These cases are not only challenging but often frustrating to both patients and physicians.
Scheffer C.G. Tseng
Oral mucosal graft has been used to correct lid margin keratinization in moderate cases of Stevens-Johnson syndrome to reduce blink-related microtrauma and associated ocular surface inflammation so as to improve visual rehabilitation. Recently, we have reported our success in using oral mucosal graft in severe cicatricial ocular surface diseases. We demonstrated the efficacy of oral mucosal graft in correcting blink-related microtrauma and restoring complete lid closure in cases of lagophthalmos. Furthermore, we confirmed that oral mucosal graft is a viable alternative to restore corneal surface integrity in cases with partial and total limbal stem cell deficiency in which transplantation of allogenic stem cells failed or was not feasible.
The clinical experience of the benefit of oral mucosal graft for treatment of limbal stem cell deficiency will markedly increase in the near future. A variety of techniques for in vivo and ex vivo expansion of oral mucosal epithelium cells has been investigated, but one notable new approach is to transplant cultivated oral mucosal epithelium for total limbal stem cell deficiency.
Hosam Sheha
Oral mucosal graft for lid margin reconstruction
Under local anesthesia, 2% lidocaine with 1:1000 epinephrine (Hospira), apply 4-0 silk traction sutures or use a Desmarres lid retractor to flip the lid and expose the tarsus.
Split the lid margin at the gray line into anterior and posterior lamellae.
Selectively excise the posterior lid margin to remove keratinization, distichiasis or any scar tissue (Figure 1a) without damaging the remaining tarsal plate.
Recess the anterior lamella and secure it to the anterior tarsal surface 3 mm to 4 mm posterior to the cleaned tarsal margin using 8-0 Vicryl mattress sutures (Ethicon) (Figure 1b).
Under lidocaine/adrenaline infiltration anesthesia, harvest a full-thickness oral mucosal graft from the inferior labial surface along with stromal fat so that the tarsal height can be lengthened.
For donor site hemostasis, apply Gelfoam (Pharmacia & Upjohn) soaked with 1,000 U/mL thrombin (Gentrac).
Secure the stromal edges of the graft to the border of the tarsal defect and then to the skin surface of the recessed lid margin using continuous 8-0 Vicryl sutures (Figures 1c and 1d).
Apply antibiotic steroid ointment and an eye patch.
Oral mucosal graft for total limbal stem cell deficiency
Under topical anesthesia, apply traction sutures using 7-0 Vicryl at the superior and inferior limbal sclera.
Perform peritomy, remove the vascularized pannus (Figure 2a), dissect any associated symblepharon and recess the conjunctiva toward the fornix.
Figure 1. Key surgical steps of oral mucosal graft for lid margin reconstruction. Selective excision of lid margin keratinization (1a). Recession and fixation of the anterior lamella onto the tarsus (1b). Securing a full-thickness oral mucosal graft to the tarsal bed to elevate the lid margin height (1c, concave dotted line). Postoperative picture showing the corrected lid margin (1d, straight dashed line). Schematic illustration showing how oral mucosal graft (orange) covers across the lid margin (1d inset).
Images: Cheng AMS, Sheha H, Tseng SCG
Figure 2. Key surgical steps of oral mucosal graft for total limbal stem cell deficiency. Superficial keratectomy and removal of the conjunctivalized pannus from the cornea along with conjunctival recession (2a). Amniotic membrane as a substrate at the limbus (2b). Thinned oral mucosal graft secured encircling the limbus (2c). ProKera placed as a temporary bandage to enhance the healing (2d).
Do superficial keratectomy as needed to remove superficial corneal opacities. If the resultant corneal surface is irregular, polish with a dental bur.
Cover the limbal area with a sheet of cryopreserved amniotic membrane using fibrin glue (Figure 2b). Amniotic membrane may be extended to cover the entire cornea as well.
Harvest a 6-mm-wide oral mucosal graft, trim the excess fat from the stromal surface, divide it into two halves longitudinally and then secure it to the limbus on top of the amniotic membrane using 10-0 nylon interrupted sutures to encircle the entire limbus (Figure 2c). Fibrin glue may be used to reinforce the attachment.
Cover the entire ocular surface with a large sheet of amniotic membrane as a patch using 10-0 nylon purse-string sutures 3 mm from the limbus or place a self-retaining amniotic membrane (ProKera, Bio-Tissue) for 1 to 2 weeks to enhance the healing process (Figure 2d).
In eyes with an exposure problem, a tarsorrhaphy is recommended.
Apply topical antibiotic steroids.
Conclusion
Ocular surface failure is multifactorial and presents with different stages of severity. Careful consideration of the etiology of ocular surface inflammation, the extent of the involvement and the degree of limbal stem cell deficiency helps tremendously in tailoring a suitable method of treatment for each patient. Other important factors are tear film and eyelid abnormalities, keratinization of the ocular surface, laterality of the disease process, and health and age of the patient.
The last few decades enjoyed the development and progress of new ocular surface reconstruction techniques including amniotic membrane transplantation, limbal stem cell transplantation, oral mucosal graft and cultivated oral mucosal epithelium. Ongoing studies represent great strides in regenerative medicine and provide promise for the ever-growing field of tissue engineering.