EyeWorld Asia-Pacific March 2018 Issue

a properly shaped result … you look at what we’re doing, what the Allo- tex team has done in the past, you make a pretty compelling case that we’re going to do it again.” While the Allotex procedure could mimic other intracorneal inlay procedures where a thin femtosecond flap is made, the al- lograft centered over the pupil, and the flap smoothed back down, Dr. Muller said they’re moving toward a less invasive onlay procedure. A small divot of the patient’s corneal epithelium would be removed and the thin allograft lenticule would be placed on top of Bowman’s membrane, tucked a bit under the epithelium, and within 6–8 hours, the epithelium would cover back over it. “Now you have a procedure where you didn’t do any surgery, just a little corneal insult,” he said. “If I want to take it out, I don’t have to do anything except reach in with forceps. We know of one doctor who was able to slide it out at the slit lamp with the patient not knowing it came out. It’s a completely different offering to the patient.” In addition to technology and surgical techniques coming of age to make corneal allografts more feasible than before, Dr. Muller said sterilization and storage methods by Lions VisionGift Vision Research Laboratory has created an economi- cal way to store sterile, ready-to-use tissue at room temperature without the need for reconstitution. Dr. Muller said Allotex is refin- ing the process engineering to take a cornea and make 150 of these button allografts out of it. At this point, Dr. Muller said he envisions stock amounts of the button lentic- ules of about 3 mm in diameter and 25 µm in central thickness being stored by physicians offering this procedure. Dr. Muller said this donor tissue can be used to make lenticules of about 5.5 mm in diameter with a central thickness of 50 to 100 µm for treatment of hyperopia. Custom lenticules could also be fashioned for patients with astigmatism. PEARL works, Dr. Muller said, because you’re taking a clinical la- ser on a clinical eye to remove a set amount of tissue and then taking a piece of that lenticule and putting it on another eye. To develop a laser system and process that allows you to take bits and pieces of a donor cornea, accurately measure and shape them, requires “millions of dollars worth of engineering to turn it from a cool idea into a real product.” The challenge with inlays and onlays—both allogenic and syn- thetic—remains patient neuroadap- tation. “In a sense, it’s a modified mon- ovision,” Dr. Muller said. “What patient population tolerates this? We don’t know that number.” However, the beauty of these inlays—and the synthetic variety— is their removability. “It becomes the holy grail, a semi-permanent contact lens that can be removed if you don’t like it or removed and replaced if the re- fraction changes. I think that’s the key message,” Dr. Muller said. “Just because refractive error/wear- ing corrective lenses is looked upon as a ‘nuisance’ and non-medical condition doesn’t mean we cannot strive to develop and offer better techniques in correcting it,” Dr. Ne- grin said. “I am all for using donor corneal tissue for this purpose pro- vided there is no scarcity of donor tissue, and we are able to reliably provide the service.” EWAP References 1. Ratner BD, et al. Biomaterials Science, Third Edition: An Introduction to Materials in Medicine. Academic Press. 2012 Dec 31;931. 2. McDonald MB, et al. The nationwide study of epikeratophakia for myopia. Am J Ophthal- mol . 1987;103:375–83. 3. Pradhan KR, et al. Femtosecond laser-as- sisted keyhole endokeratophakia: correction of hyperopia by implantation of an allogenic lenticule obtained by SMILE from a myopic donor. J Refract Surg. 2013;29:777–82. 4. Jacob S, et al. Preliminary evidence of successful near vision enhancement with a new technique: PrEsbyopic Allogenic Refractive Lenticule (PEARL) corneal inlay using a SMILE lenticule. J Refract Surg. 2017;33:224–29. 5. Ganesh S, et al. Cryopreservation of extracted corneal lenticules after small inci- sion lenticule extraction for potential use in human subjects. Cornea. 2014;33:1355–62. Editors’ note: Dr. Muller has financial interests with Allotex. Dr. Jacob has financial interests with instruments she uses to perform CAIRS. Dr. Negrin has no financial interests related to her comments. Contact information Jacob: dr_soosanj@hotmail.com Muller: info@allotex.com Negrin: asnreis@gmail.com Appasamy Associates Page: 29 www.appasamy.com Beaver-Visitec Int. Page: 20 www.beaver-visitec.com Diamatrix Ltd. Page: 22 www.diamatrix.com Haag-Streit AG Page: 25 www.haag-streit.com Oculus Optikgeräte Page: 37 www.oculus.de Ziemer Page: 64 www.ziemergroup.com World Ophthalmology Congress Page: 34 www.woc2018.org ASCRS Page : 2, 17, 48 www.ascrs.org APACRS Page : 7, 10 , 11 , 62 , 63 www.apacrs.org EyeWorld Page : 5, 18 , 32 , 40 , 41 , 54 www.eyeworld.org Cornea Society Page: 57 , 61 www.corneasociety.org Index to Advertisers EWAP REFRACTIVE 47 September 2017 March 8