Simple Limbal Epithelial Transplantation (SLET)

All content on Eyewiki is protected by copyright law and the Terms of Service. This content may not be reproduced, copied, or put into any artificial intelligence program, including large language and generative AI models, without permission from the Academy.

Article initiated by:

Esteban A. Santiago, MD.

All contributors:

Hinali Patel, Vatinee Y. Bunya, MD, MSCE, Esteban A. Santiago, MD., Christina Moon, M.D., Colleen Halfpenny, M.D., Maria D. Bernal, MD, Kendra L. Hong, MD

Assigned editor:

Maria D. Bernal, MD

Review:

Assigned status Up to Date

 by Maria D. Bernal, MD on February 28, 2026.

add
Contributing Editors:	add

Introduction

Figure 1: Unilateral LCSD in an eye after an alkaline corneal burn from an oven cleaner splash injury.

Simple limbal epithelial transplant (SLET) is a surgical technique used to treat unilateral limbal stem cell deficiency (LSCD) and was first described by Sangwan, et al. in 2012. In LCSD, the corneal epithelium is unable to repair itself, leading to persistent corneal epithelial defects, conjunctivalization, neovascularization, scarring, inflammation, and vision loss (Figure 1). SLET restores the limbal stem cells by transplanting healthy limbal stem cells from the healthy contralateral eye onto the affected cornea, facilitating regeneration of a transparent corneal epithelium.

Background

Historical Evolution of Autologous Limbal Stem Cell Transplantation

Autologous limbal stem cell transplantation for unilateral LCSD has evolved over several decades, and several transplantations techniques were performed prior to SLET. In these surgeries, the affected eye first undergoes a peritomy and keratectomy to remove the fibrovascular pannus on the cornea, which is followed by graft harvesting and implantation as below.

• Conjunctival limbal autografting (CLAU) (Kenyon and Tseng, 1989): Two conjunctival-limbal lenticules measured at 4 clock hours each are harvested from the healthy eye and sutured to the limbus in the recipient eye. CLAU requires removal of substantial limbal tissue of up to 50% and can be associated with iatrogenic LSCD in the healthy eye.
• Cultivated limbal epithelial transplantation (CLET) (Pellegrini et al., 1997): A small 2x2 mm limbal tissue from the healthy eye is first harvested from the healthy eye and then undergoes ex-vivo cellular expansion in a clinical laboratory for 10-21 days to create a multilayered sheet of corneal epithelium. This sheet is transplanted onto the cornea in the affected eye and secured with 10-0 sutures. Although less limbal tissue was harvested, this technique requires a laboratory to cultivate the stem cells and is a two-stage procedure, making it challenging in resource-limited settings.
• Simple Limbal Epithelial Transplantation (SLET) (Sangwan et al., 2012): SLET combines the advantages of CLAU and CLET. A 2 to 3-mm segment of limbal tissue is harvested from the contralateral healthy eye, divided into 10-12 pieces, and then glued evenly on an amniotic membrane in the recipient eye cornea. The amniotic membrane acts as a scaffold to support the in-vivo expansion of limbal cells.

Pathophysiology of LCSD

Figure 2: Limbal epithelial stem cells are found at the limbus in the palisades of Vogt, migrate centripetally, and differentiate into corneal epithelial cells. Reference: Mannis MJ, et al. Cornea. 2021

The limbus is located at the corneoscleral junction and houses stem cells in the palisades of Vogt that are responsible for constant regeneration and renewal of the corneal epithelium. The stem cells generate epithelial progenitor cells that migrate centripetally and eventually differentiate into corneal epithelial cells to maintain epithelial integrity and heal epithelial defects (Figure 2). Approximately 25-33% of limbus must be present to maintain corneal epithelial integrity.

Causes for LCSD include chemical exposure, thermal burns, autoimmune cicatrizing disease (Stevens-Johnson Syndrome, mucous membrane pemphigoid), chronic inflammation or infection, severe dry eyes, and iatrogenic damage from surgery or medications. Clinical signs of LCSD include persistent corneal epithelial defects, pannus formation, conjunctivalization, neovascularization, and inflammation.

Patient Selection

Indications

Unilateral LSCD is the primary indication. The pathology in the recipient eye should be limited to the epithelium with minimal stromal opacification. Causes of unilateral LSCD include:

• Trauma: chemical exposure, thermal burns
• Ocular disease: Anterior segment ischemia, neoplasia, infection (e.g., herpes, trachoma), degeneration (e.g., pterygium), neurotrophic keratitis
• Iatrogenic: prior ocular surgery such as pterygium excision, mitomycin C exposure, cryotherapy, and conjunctival resection

Contraindications

SLET is not recommended for bilateral LSCD such as Stevens-Johnson Syndrome (SJS) and toxic epidermal necrolysis, mucous membrane pemphigoid, graft-vs-host disease, bilateral burns, and bilateral infections because there is no suitable donor eye. These patients could benefit from allogenic SLET from cadavers or related living donors but would likely require long-term systemic immunosuppression. Patients with chronic bilateral contact lens wear are also poor candidates due to reduced limbal stem cell reserve from chronic mechanical trauma and hypoxia.

Pre-operative preparation

The ocular surface needs to be optimized before surgery in order to provide the new stem cells a proper environment for their expansion. It is common to find ocular surface inflammation in eyes with chemical or thermal burns or other causes of longstanding limbal stem cell deficiency. This inflammation needs to be treated before performing SLET. Depending on the specific case, options such as oral Doxycycline, topical Cyclosporine, non-preserved artificial tears, etc should be used. Using non-preserved drops is important in order to avoid adding more toxicity to the eye and should be used before and after surgery. Eyelid problems need to be corrected before SLET.

Surgical Technique

Step 1: Application of brimonidine 0.15% and phenylephrine 5% drops 5-10 minutes before surgery reduces intraoperative bleeding in the donor and recipient eyes. Use topical anesthesia in both eyes and a peribulbar in the LSCD eye. Some surgeons prefer to do peribulbar in both eyes. General anesthesia for children. Prep both eyes as usual and drape first the donor eye.

Step 2: An approximate 2mm area in the superior limbus is identified (the donor limbus is not marked with a skin-marking pen, as the alcohol in the ink can damage the delicate limbal stem cells) and marking is done slightly behind the limbus on the conjunctiva. A conjunctival bleb is created with fluid just behind the selected area of the biopsy and a limbus based conjunctival flap is created 1 to 2 mm away from the limbus; dissection is continued toward the limbus. When the limbus is reached, using a Crescent blade or N15 Surgical blade dissection continues for 1mm into clear cornea. The conjunctival flap will be cut apart from the donor limbus and the limbus excised using forceps and Vannas scissors. The conjunctiva will be repositioned and held in place using fibrin glue or sutures. The limbal tissue is preserved in balanced saline solution to prevent drying.

Step 3: After prepping and draping of the recipient eye, a 360 peritomy about 2-3 mm beyond the estimated limbus is done and all the vascular pannus removed from the cornea with careful blunt and sharp dissection. Attempts to manually debulk the cornea stroma to reach a clearer plane is strongly discouraged. Removing the pannus is a crucial step to provide the proper surface for the stem cells to expand. The cornea and bare sclera are covered with human amniotic membrane (HAM, basement membrane side up). The HAM is held in place with fibrin sealant. It is critical to ensure that the HAM is tucked under the conjunctival edge in all quadrants. The HAM is smoothened out over the cornea with a blunt spatula to make sure there are no folds.

Step 4: After the HAM is glued in place, the limbal tissue is removed from the BSS and cut in about 6-10 pieces with Vannas scissors directly over the HAM. These pieces are placed (epithelium side up) in the mid peripheral cornea in a circular fashion. The correct orientation of the small pieces can be identified from the pigmentation and/or smooth surface of the epithelial side and the white fibrous strands on the stromal side. Care is taken to ensure that the pieces are not placed over the pupillary area or the limbus. A drop of fibrin sealant is placed over each piece of limbal tissue.

Step 5: When the fibrin sealant is polymerized and everything looks stable, a large diameter contact lens is placed followed by antibiotic and steroid drops.

Successful Glueless SLET with Femtosecond Laser- Assisted and without has been published.

SLET without amniotic membrane case reports have demonstrated comparable success. In this technique, limbal explants are placed directly on the denuded cornea and covered with a bandage contact lens. Larger studies are needed to validate this scaffold-free approach.

Post-operative care

Patients are usually followed up on day one, 1 week and 1 month after surgery, and thereafter according to specific needs. The contact lens should stay in place for 7 to 10 days. V Mittal et al. reported a complete epithelialization of the corneal surface by the second week, and a transparency of the explants by the 8^th week. In the same publication Dr. Mittal et al. showed that the epithelialization and explants transparency process was faster in children than in adults . The HAM will take a few weeks to dissolve and the time will depend on its thickness. The reports have shown an efficacy of 83% restoring the ocular surface and preventing the conjuntivalization of the cornea . None of the donor eyes developed stem cell deficiency.

Complications

Some common complications during the post-op period are displacement of the grafts or the HAM, the former is more common when there is bleeding under the HAM after the surgery. The most commonly reported complication is the recurrence of conjunctivalization. Clinical factors that have been associated with failure are acid injury, severe symblepharon, combination with keratoplasty and postoperative loss of explants .

Conclusion

SLET has shown to be an efficient and cost-effective surgical technique for the restoration of the ocular surface in cases of partial and complete LSCD . R. Arora et al. did a prospective study comparing SLET vs CLAU, and they concluded that both procedures were equally effective, and both provided stable results . SLET has a relatively short learning curve and has made life easier for corneal surgeons.

References

21. Marwan Raymond Atallah; Sotiria Palioura;
Victor L Perez;
Guillermo Amescua. Limbal stem cell transplantation: current perspectives. Clinical Ophthalmology 2016:10 593–602.