Is it feasible for a refractive surgery clinic to store and reuse SMILE lenticules?
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It should be a priority on the agenda of regulatory agencies worldwide
SMILE surgery is becoming more and more popular and successful, and is now a driver in our high-volume clinic.
I have always felt it is a shame to dispose of this portion of healthy cornea and truly believe we should make use of it. High-volume refractive clinics could set up their eye bank facilities for storage, where the law allows for it. In European countries, regulations are based on cadaver eye tissue, and we need to review and update them to allow for the use of tissue from living donors. This should be a priority on the agenda of regulatory agencies worldwide because an increasing amount of tissue that we could potentially use is currently, and unacceptably, going to waste.
I believe that most patients, in countries where there are no religious or cultural barriers to donation, would be happy to collaborate in a program of tissue reuse. I would not bother them with serological testing, but rather test the tissue. The risk of infection from microbial transmission is extremely low. Here in the Czech Republic, prion testing is required, but I believe this law is obsolete, because there are no reported cases of Creutzfeldt-Jakob disease from corneal transplantation. As far as COVID-19 transmission is concerned, the concerns regarding infection through donor corneal tissue have been dispelled by researchers. Traces of viral RNA may be there, but not the active virus.
Using fresh lenticules for tissue-addition procedures would be ideal, but it may not be so frequent to have donor and recipient operated on the same day, so I rather foresee cryopreservation as a method for storing and then reusing lenticules. There are interesting and fairly well-established tissue-addition procedures for refractive surgery, and I find this approach particularly appealing for keratoconus. With a minimally invasive method, you can increase corneal thickness and strength and reshape the cornea to improve vision. You can also cross-link the lenticule before implantation and safely perform topography-guided PRK. It is really a very safe and effective way of treating keratoconus, something that promises to become even more popular than corneal ring segment implantation.
In my practice, I have been using biosynthetic inlays for presbyopia, but will welcome the opportunity to use SMILE lenticules if the law allows us to do so. In our center, we did more than 100 hyperopic SMILE procedures in a clinical study for hyperopic SMILE CE mark for Zeiss, and it will be great to use concave lenticules from hyperopic SMILE for keratoconus.
Pavel Stodulka, MD, PhD, is from Gemini Eye Clinics, Zlin and Prague, Czech Republic, and Vienna, Austria.
Too many barriers, better managed by an eye bank
The use of repurposed SMILE lenticules is intriguing, and the clinical outcome can be the same, but there are problems that are barriers for a refractive surgery center to maintain and manage storage and reuse of SMILE lenticules.
First, the storage and reuse of SMILE lenticules would require the clinic to register as a Tissue Establishment with the FDA (https://www.fda.gov/vaccines-blood-biologics/biologics-establishment-registration/tissue-establishment-registration) and comply with FDA regulations. The effort to register, maintain compliance and endure routine FDA inspection would be a challenging distraction from patient care, and something that incurs significant financial cost and likely financial loss.
Second, each patient providing a lenticule would have to undergo FDA-required donor screening, which, in turn, would require additional staff time and costs, thus making this an even less attractive option.
Third, the long-term (10-plus years) maintenance of all donor and recipient records would be onerous and risky for a clinic. Any lapse in these records would be revealed during an FDA inspection and could be costly and awkward for a clinic.
Additionally, FDA approvals: If they make any claim about the product (+2 D, for instance), then it will have a second set of regulatory requirements. In fact, FDA considers corneal tissue used for refractive purposes to be a Class 3 device requiring an investigational device exemption and premarket approval. There is no workaround.
Finally, precision: To get a predictable result with an allogeneic implant requires that it be produced with the same accuracy and precision that we get with in vivo excimer laser tissue ablation with LASIK or PRK. Because the shape of a retrieved SMILE lenticule is donor-dependent, it will need to be laser-machined into the proper shape for the recipient. This is a very difficult process and cannot easily be accomplished with a clinical excimer laser.
While I am a big supporter and believer in the use of allogeneic tissue to treat refractive errors, including presbyopia, I do not think it will be possible to organize the production, storage and distribution of SMILE lenticules in the context of a commercial operation.
There are multiple eye and tissue banks across the country that could serve this function as a partner of multiple refractive surgery centers wishing to reuse SMILE lenticules. Let’s find and support a great eye bank partner to open up this option for all clinics.
Vance M. Thompson, MD, an OSN Refractive Surgery Board Member, is from Vance Thompson Vision, Sioux Falls, South Dakota.
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