Eyeworld

81 EW CORNEA September 2018 by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer SMILE lenticules employed in patients with corneal defects show promising outcomes N ew evidence suggests that allogenic corneal lenti- cule transplantation may offer surgeons a viable option for the manage- ment of complicated corneal ulcers. According to the outcomes of a case series presented by Pavel Studeny, MD, University Hospital Kralovske Vinohrady, Prague, Czech Repub- lic, who spoke at the 22nd ESCRS Winter Meeting, lenticule transplan- tation 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 antifun- gals, 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 transplanta- tion, 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 hyper- opia 1 and even in the treatment of presbyopia. 2 SMILE reduces inflam- matory and wound healing re- sponses 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 pos- sibility 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 join- ing 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 Repurposing stromal lenticules " 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 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 op- erations for ectropion on the right eye. He presented with a persistent right-sided corneal ulcer and under- went lenticule transplantation with amniotic membrane covering. After 1 week, the patient's right cornea appeared to be improving, the ulcer- ation healing, and by 2 months after surgery corneal clarity had been much improved. In a third case scenario, Dr. Stu- deny described a 47-year-old male patient who suffered a severe alkali burn, causing a persistent corneal defect on his right cornea. The pa- tient had a limbal stem cell insuf- ficiency 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 ob- served an improvement as early as 1 week after transplantation, with a much stabilized cornea at 2 months. Stromal lenticules SMILE is a refractive surgical tech- nique implemented to correct myo- pia and astigmatism. It distinguishes itself from other refractive laser sur- geries in that the femtosecond laser is used to cleave a thin stromal lenti- cule from within the corneal stroma for manual extraction through a tunnel incision made in the periph- eral 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 cryopreserva- tion 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 lenti- cules 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, in- formed 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 in- vestigate the presence of infectious diseases (hepatitis A, B, C, syphilis, HIV). Evidence suggests that stromal lenticules extracted from ReLEx surgery remain viable after cryo- preservation, with their collagen architecture well preserved and good cellular viability. 3 Once the corneal lenticule is thawed at room tem- perature, it can be sewn onto the recipient's cornea, using individual sutures, and covered with an amni- otic membrane. In the preliminary findings of a study that applied stromal lenticules extracted by SMILE surgery for seven continued on page 82 Presentation spotlight

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