September 2018

CORNEA

Presentation spotlight
Repurposing stromal lenticules


by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer

“The lenticule is cut from within the cornea by femtosecond laser and mechanically released and removed from the eye. It is a waste product
of the operation that we can use to repair the cornea.”
—Pavel Studeny, MD

One week after transplantation of lenticule and amniotic membrane

Outcome after corneal tissue lenticules from ReLEx SMILE for the treatment of corneal ulcer
Source: Pavel Studeny, MD

SMILE lenticules employed in patients with corneal defects show promising outcomes

New evidence suggests that allogenic corneal lenticule transplantation may offer surgeons a viable option for the management of complicated corneal ulcers. According to the outcomes of a case series presented by Pavel Studeny, MD, University Hospital Kralovske Vinohrady, Prague, Czech Republic, who spoke at the 22nd ESCRS Winter Meeting, lenticule transplantation is a good way to repurpose stromal material.
“Corneal ulcer treatment can be challenging, at times needing a surgical intervention. Corneal tissue lenticule transplantation may be considered as an alternative method for the treatment of corneal ulcers,” Dr. Studeny said. “It seems to be safe and effective to cover non-healing corneal defects, even temporarily, and is an effective use of a ‘waste product’ left over from ReLEx SMILE surgery.”

Treating corneal ulcers

Treatment of corneal ulcers begins conservatively with agents such as antibiotics, antivirals, and antifungals, both locally and systemically, as well as steroids, antiphlogistics, mydriatics, and immunosuppressive drugs. Surgical therapy may differ depending on the size of the defect. For smaller defects, eye surgeons use amniotic membrane transplantation, tissue glue, and a conjunctival patch made up from donor’s cornea. Larger defects and those resistant to therapy may necessitate acute keratoplasty.
Corneal lenticules derived from refractive SMILE surgery have proven to be useful in a number of ways. Allogenic lenticules obtained through SMILE surgery have been successfully used to correct hyperopia1 and even in the treatment of presbyopia.2 SMILE reduces inflammatory and wound healing responses and also respects epithelial and basement membrane integrity through the absence of a flap. These factors allow for better graft-host acceptance and may reduce recovery time.
“We wanted to verify the possibility of using corneal lenticules obtained during refractive surgery ReLEx SMILE for the treatment of corneal ulcers,” Dr. Studeny said. “The lenticule is cut from within the cornea by femtosecond laser and mechanically released and removed from the eye. It is a waste product of the operation that we can use to repair the cornea.”

Case studies

Dr. Studeny presented three cases in which he implanted lenticules that were derived from ReLEx SMILE refractive surgery donors. The first case scenario described a 45-year-old female patient who was operated on for a meningioma with resultant left-sided facial nerve palsy. Three months after the operation, the patient underwent a partial joining of the upper and lower eyelids (tarsorrhaphy) of her left eye. Due to persistent corneal ulceration in the afflicted left eye, the patient received three amniotic membrane transplantations, within a 13-month time period, all three of which were unsuccessful. As a final attempt, Dr. Studeny implanted a lenticule in the patient’s affected eye with an amniotic membrane covering but was forced to carry out classical perforating keratoplasty 1 week after the implantation.
A second case involved the treatment of a 73-year-old male patient with congenital ectropion and congenital facial nerve palsy. The patient underwent multiple operations for ectropion on the right eye. He presented with a persistent right-sided corneal ulcer and underwent lenticule transplantation with amniotic membrane covering. After 1 week, the patient’s right cornea appeared to be improving, the ulceration healing, and by 2 months after surgery corneal clarity had been much improved.
In a third case scenario, Dr. Studeny described a 47-year-old male patient who suffered a severe alkali burn, causing a persistent corneal defect on his right cornea. The patient had a limbal stem cell insufficiency and areas of extreme focal corneal thinning (descemetocele). He underwent amniotic membrane transplantation twice on his right eye, unsuccessfully. After corneal lenticule and amniotic membrane transplantation, Dr. Studeny observed an improvement as early as 1 week after transplantation, with a much stabilized cornea at 2 months.

Stromal lenticules

SMILE is a refractive surgical technique implemented to correct myopia and astigmatism. It distinguishes itself from other refractive laser surgeries in that the femtosecond laser is used to cleave a thin stromal lenticule from within the corneal stroma for manual extraction through a tunnel incision made in the peripheral cornea. The extracted lenticules can be cryogenically preserved and saved for a later date.
ReLEx SMILE was performed according to the standard operating protocol. The removed lenticular specimen was aseptically stored in a container with a cryopreservation solution. The sample was then stored and frozen in an eye tissue bank, according to the standard procedure used for freezing amniotic membranes, and kept in quarantine, Dr. Studeny explained. The lenticules can be used 6 months after the donor’s control laboratory tests are completed, he said.
Obtaining a corneal lenticule from the donor cornea follows the same protocol as for amniotic membrane extraction, Dr. Studeny said, involving the signed, informed consent of the donor. The transplantation also requires the informed consent of the recipient. For lenticules to be viable, a number of exams are carried out: serological and virological exams involving a blood sample from the donor to investigate the presence of infectious diseases (hepatitis A, B, C, syphilis, HIV).
Evidence suggests that stromal lenticules extracted from ReLEx surgery remain viable after cryopreservation, with their collagen architecture well preserved and good cellular viability.3 Once the corneal lenticule is thawed at room temperature, it can be sewn onto the recipient’s cornea, using individual sutures, and covered with an amniotic membrane.
In the preliminary findings of a study that applied stromal lenticules extracted by SMILE surgery for seven eyes with corneal perforations, lenticule transplantation seemed safe and effective as an adjuvant for the closure of corneal perforations. The investigators maintained that lenticules have a potential clinical application, as relatively simple and inexpensive temporary measures, to improve the corneal condition until further definitive interventions could be carried out. The study applied lenticules with central corneal thickness of at least 100 µm using interrupted stitches and a single layer of overlying amniotic membrane. The corneal perforations were sealed in all seven patients, with no evidence of infection, relapse, or reperforation detected in the 12 months following transplantation.4
“Corneal lenticule transplantation could be the method of choice for deep defects. In the future, these lenticules could be considered for treatment of other conditions like hyperopia and keratoconus,” Dr. Studeny said.

References

1. Pradhan KR, et al. Femtosecond laser-assisted keyhole endokeratophakia: correction of hyperopia by implantation of an allogeneic lenticule obtained by SMILE from a myopic donor. J Refract Surg. 2013;29:777–82.
2. Lim CH, et al. LASIK following small incision lenticule extraction (SMILE) lenticule re-implantation: a feasibility study of a novel method for treatment of presbyopia. PLoS One. 2013;8:e83046.
3. Mohamed-Noriega K, et al. Cornea lenticule viability and structural integrity after refractive lenticule extraction (ReLEx) and cryopreservation. Mol Vis. 2011;17:3437–49.
4. Abd Elaziz MS, et al. Stromal lenticule transplantation for management of corneal perforations; one year results. Graefes Arch Clin Exp Ophthalmol. 2017;255:1179–1184.

Editors’ note: Dr. Studeny has no financial interests related to his comments.

Contact information

Studeny
: studenypavel@seznam.cz

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