FP1141 : Simple Limbal Epithelial Transplantation – A Novel Technique

Dr.Thungappa K S, K15949, Dr. Yathish Shivanna,Dr. Rashmi Deshmukh, Dr. Harsha Nagaraja

SLET- A NOVEL TECHNIQUE

Introduction:

The microenvironment of stem cell niche is disturbed by many intrinsic and extrinsic factors. There are many causes oflimbal stem cell deficiency (LSCD) like chemical injury, thermal injury, Steven-Johnson syndrome, mucous membrane pemphigoid(1). Simple limbal epithelial transplantation (SLET) was introduced by Sangwan et al for the treatment of unilateral limbal stem cell deficiency (2). In this technique, a2 × 2 mm strip of donor limbal tissue is obtained from the healthy eye and divided into eight to ten small pieces. The tiny limbal transplants are distributed evenly over an amniotic membrane placed on the cornea (2).  Post-operative loss of transplants is a known factor causing failure of SLET (3). We present the results of our modification of the procedure and its outcomes studied in 8 eyes of unilateral LSCD.

Methods:

The study was approved by the Ethics Committee of NarayanaNethralaya Hospital and was performed in accordance with the guidelines of the Declaration of Helsinki. Informed consent of study subjects was obtained at the time of enrollment. It was a cross sectional study that included 8 patients with unilateral LSCDsecondary to chemical or thermal injury. Patients with total/partial LSCD with more than 8 clock hours oflimbal stem cell loss were included in the study. All patients included in the study underwent a detailed ophthalmic evaluation and were under treatment since minimum 3 months with no signs of improvement.The primary outcome measure was restoration of a completely epithelized, stable, and avascular corneal surface. The secondary outcome measure was improvement in visual acuity. Complications, risk factors for failure, and immunohistochemistry analysis of corneas that underwent SLET also were described.

Surgical technique:

This single stage surgery was done under local/general anaesthesia.A 2X2 mm of limbal strip was harvestedfrom superior  limbus of the healthy contralateral eye and was placed in balanced salt solution.Conjunctivalperitomy , dissection and proper removal of fibrovascular tissue was carried out.Harvested limbal strips were cut into 8-10 tiny pieces on the teflon block using 15 no blade. Fibrin glue (Tessel- from Baxter,Vienna,Austria) was applied on the ocular bed and tiny pieces of grafts were placed equidistant avoiding visual axis. Then amniotic membrane graft (AMG)  was placed with its epithelial side up covering the entire ocular surface. A bandage contact lens (BCL) was applied at the end of the procedure. Patients were reviewed on day 1,7,14,30 and then every month for 6 months. Post-operative medications included topical gatifloxacin 0.3%, Prednisone 1% eye drops tapering over 2 months, carboxymethyl cellulose 1% 4-6 times a day for 6 months. The BCL was removed after 2 weeks.

Results:

Mean follow up was 22.15  +/- 8.33 months (range 12-30 months). There were 7 patients with alkali injury and 1 patient with thermal injury. Four patients achieved BCVA of 20/60 and more. Successful outcome was observed in all patients with chemical injury and partially successful outcome was seen in the patient with thermal injury.

Discussion

The surgical techniques available for unilateral LSCD include conjunctivallimbalautograft (CLAU), cultivated limbal epithelial transplant (CLET) and simple limbalepithelial transplant (SLET). However, CLAU is associated with poor success rate,delayed corneal epithelialisation,greater scarring, anddonor complications(4). CLET on the other hand, is a multi-stage procedure and requires a stem cell laboratory (5). Compared to CLAU and CLET, SLET is a single stage procedure and easy. However, post-operative loss of limbal stem cell transplant tissue is a known complication (3). In this modified technique, the transplant tissues were placed beneath the AMG that prevented their post-operative loss. Of the 8 eyes studied, the outcome was successful in all the eyes. None of the eyes had any loss of transplant tissue.

Conclusion

The modified SLET technique is an effective , safe and replicable method to treat unilateral LSCD the advantage being it reduces the risk ofpostoperative loss of  tiny limbal grafts ,which is an important cause of failure of SLET.

References

1. Atallah MR, Palioura S, Perez VL, Amescua G. Limbal stem cell transplantation: current perspectives. ClinOphthalmolAuckl NZ. 2016 Apr 1;10:593–602.
2. Sangwan VS, Basu S, MacNeil S, Balasubramanian D. Simple limbal epithelial transplantation (SLET): a novel surgical technique for the treatment of unilateral limbal stem cell deficiency. Br J Ophthalmol. 2012 Jul;96(7):931–4.
3. Basu S, Sureka SP, Shanbhag SS, Kethiri AR, Singh V, Sangwan VS. Simple Limbal Epithelial Transplantation: Long-Term Clinical Outcomes in 125 Cases of Unilateral Chronic Ocular Surface Burns. Ophthalmology. 2016 May;123(5):1000–10.
4. Dua H, Azuara-Blanco A. Autologous limbal transplantation in patients with unilateral corneal stem cell deficiency. Br J Ophthalmol. 2000 Mar;84(3):273–8.
5. Burman S, Sangwan V. Cultivated limbal stem cell transplantation for ocular surface reconstruction. ClinOphthalmolAuckl NZ. 2008 Sep;2(3):489–502.