EyeWorld India March 2021 Issue

T he ZEISS Live Webi- nar on June 15, 2020 was a continuation from the June 9, 2020 webinar on Small Inci- sion Lenticule Extraction (SMILE). Experts came together to provide new clinical perspectives on di- agnostic technologies, molecular markers, and biomechanics as well as management and prophy- laxis during refractive surgery in the COVID-19 environment. SMILE Lenticules and Stem Cells as a Treatment for Corneal Blindness Dr. John Males first presented the use of stem cells as a treatment for corne- al blindness. Dr. Males began by dis- cussing human tissue as a precious resource and that the WHO estimates 10 million people worldwide would benefit from corneal transplantation for issues such as corneal blind- ness or reduced vision from corneal disease. Availability of corneal tissue is relatively poor in many parts of the world. Dr. Males eventually wondered what SMILE lenticules could offer to patients with corneal pathology. When SMILE procedures are performed, what happens to the corneal tissues and what proportion of lenticules are discarded after surgery? In corneal blindness, a significant proportion of these cases are due to limbal stem cell failure, which can be caused by chemical injuries, burns, ocular sur- face neoplasia, or surgery. In Dr. Males’ work, he investigat- ed the use of SMILE lenticules as a scaffold to grow and proliferate limbal stem cells. With this project, patients undergoing ReLEx SMILE proce- dures were offered to participate in the study and there was a 70% acceptance rate in this entirely vol- untary study. From the initial results, epithelial cell proliferation could be seen on the surface of the lenticules 8 days after removal. Another method that was utilized to image the stem cell growth was through embedding confetti corneal cells into the surface of the lenticules and Dr. Males saw that the cells would migrate across the surface. This study offered po- tential applications of treating ocular surface disorders and limbal stem cell failure. Additionally, if lenticules can be preserved, perhaps this method can be a gift to other patients in need of corneal tissue. Managing Astigmatism Correction in SMILE In the next presentation, Dr. Shreyas Ramamurthy discussed astigmatism correction in SMILE procedures. Starting with a background on astigmatism in refractive surgery, Dr. Ramamurthy explained that cyclo- torsion, if not corrected, can induce under correction and aberrations es- pecially in patients with high astigma- tism. Average cyclotorsion is about 3 degrees, and a 7 degree rotation could reduce efficacy by about 25%. Currently, cyclotorsion compensation New Advancements in Refractive Surgery: Supplement to EyeWorld Asia-Pacific March 2021 APACRS in SMILE procedures is perfrormed by manual marking and rotation. There is no automated tracking or registration feature available yet. In one study, Dr. Ramamurthy conducted a prospective interven- tional case series to compare visual outcomes following cyclotorsion compensation versus no compensa- tion in SMILE for high astigmatism. Patients had manifest cylindrical re- fraction of 1.5 D or more and bilateral high myopic astigmatism in addition to cyclorotation of > 5 degrees. Patients underwent SMILE and a slit lamp marking was made at 7mm of the central cornea and intraopera- tive cyclotorsion was measured. The results showed that intraoperative cyclotorsion was lower in the com- pensation group compared to the no compensation group, though the difference was not significant. Alpins criteria were also determined with no differences in either group. COVID Times: Do We Have Any Reason to Smile? Dr. Gaurav Luthra presented next on SMILE procedures during the COVID-19 pandemic. In late March, refractive surgery procedures sud- denly came to a standstill due to the lockdown. At this point in time, the demand for refractive surgery began to lean towards the younger population due to their lower health risks. In addition, patients who are working from home have more time to recuperate if they choose to undergo surgery, and colleges have closed, meaning more time for students to re- cover. Thus, LASIK procedures have increased in May. So, which proce- dures are safe to perform during this time? One has to consider a variety of factors: ocular virus load and infec- tivity, COVID-19 status of the patient and surgeon, the operating environ- ment, aerosol generation, and tissue fluid exposure. Dr. Luthra presented results from an aerosol generation benchmark study performed at Narayana Neth- ralya showing droplets spreading up to 11 inches during microkeratome incision. Therefore, microkeratome may not be the best procedure mov- ing forward. In Trans PRK, however, the procedure is completed in a single step with no tissue waste and minimal movement. Manual PRK, on the other hand, produces potential aerosols with Amoil’s brush. For both Trans and Manual PRK, contact lens wear is not the best option during the COVID-19 pandemic due to the con- tact lens coming in contact with the ocular tissue. Intent care must also be taken for postoperative care and multiple office visits after surgery. Dr. Luthra explained that the best way forward is the SMILE procedure due to its single step procedure with no aerosol generation, no plume, and no tissue waste. The patient is also facing away from the surgeon during the procedure and most of the proce- dure can be done watching a screen. From the patient’s perspective, there is minimum time in the operating room, faster recuperation, fewer pre- cautions, and fewer hospital visits. In Dr. Luthra’s own experience in the operating room, he performed COVID-19 testing in patients during the month of May. Surgeons, staff, and patients wear an N95 mask. Surgeons additionally wear protective glasses and knee length shoe covers. At the end of the procedure, all dis- posables are discarded as safely as possible. Another precautionary tech- nique is to perform a betadine gargle and nasal spray before procedures as it kills all the germs in the mucosa, even in COVID-19 positive patients. The news magazine of the Asia-Pacific Association of Cataract & Refractive Surgeons Figure 1. Embedding confetti corneal cells into the surface of the lenticules allows for visualizing the cells proliferating and migrating across the surface. Source: Park, Nguyen, Richardson, et al. Unpublished. Copyright 2021 APACRS. All rights reserved. The views expressed here do not necessarily reflect those of the editor, editorial board, or publisher, and in no way imply endorsement by EyeWorld, Asia-Pacific or APACRS.