Eyeworld

66 | EYEWORLD | MAY 2020 C RESEARCH HIGHLIGHT ORNEA Contact Nattis: asn516lu@gmail.com Karamichos: Dimitrios-Karamichos@ouhsc.edu by Rich Daly Contributing Writer R esearch has found adult stem cells to be "moderately effective" in treating advanced keratoconus. A prospective, interventional, nonrandomized series showed that intrastromal implantation of autolo- gous adipose-derived adult stem cells (ADASC), with or without sheets of decellular- ized donor human corneal stroma, was mod- erately effective for the treatment of advanced keratoconus and did not result in complications at 1 year of follow up. The study 1 included 14 consecutive pa- tients who were divided into those that received implantation of autologous ADASC alone, de- cellularized donor 120-μm thick corneal stroma lamina alone, and recellularized donor lamina with autologous ADASC with another layer of cells at the time of the surgery. The ADASC were obtained by elective liposuction. Implantation was performed in the corneal stroma through a femtosecond laser-assisted 9.5-mm diameter lamellar dissection under topical anesthesia. In addition to the lack of complications, there were no lines of visual acuity lost among the participants. Corrected distance visual acuity improved by 0.231, 0.264, and 0.094 Snellen lines, respectively. In the latter two groups, sphere improved by 2.35 D and 0.625 D, respectively. Corneal thickness improved by a mean of 14.5 μm in the first group and 116.4 μm in the latter two groups. New collagen production was observed at the surgical plane in the first group. The results are preliminary, and larger follow-up studies are needed to further analyze the safety and efficacy of this technique as well as long-term results. "Although techniques such as crosslinking and corneal transplantation are good for treat- ment of keratoconus, to have [other] techniques available, which may be able to help patients who do not qualify for crosslinking or trans- plantation, can add to our 'tool box' as a way of treating our patients," said Alanna Nattis, DO, adding that more data is needed to ensure cor- neas remain stable over several years, without any evidence of rejection, late scarring, haze, or increased ectasia. Dimitrios Karamichos, PhD, who studies corneal surgery, said the results were "signif- icant" and "different" but warned that the results were not compared to available cross- linking options. "We need a treatment, but those patients need the option of the cornea transplant once they get to this stage, so what the authors are suggesting is just a different way to approach it," Dr. Karamichos said. Practice impact More expansive results like those in the study could impact Dr. Nattis' practice. "I think that if success can be shown in larger patient cohorts, this may become a treatment modality for some difficult-to-treat keratoconus cases in the future," Dr. Nattis said. "Additionally, the techniques described may serve as a novel way to treat other corneal dystrophies down the road." Dr. Karamichos stressed the need for more established results before this technique could make it to clinical practice. Need continues The current standard of care for keratoconus management—aside from spectacles, contact lenses, and intracorneal ring segments to im- prove vision—consists of collagen crosslinking and corneal transplantation. Crosslinking has risks of decreased or distorted vision from corneal haze, and corneal transplants can result in astigmatism, risk of rejection, haze, and scar- ring, the study authors noted. Dr. Nattis said having another treatment modality that offers lower visual risks would be welcome. Very advanced cases of keratoconus, which often are contraindicated for crosslinking, were treated with this technique, which Dr. Nattis said could fill an unmet need. Adult stem cells treat advanced keratoconus About the doctors Alanna Nattis, DO Associate clinical professor of ophthalmology and surgery New York Institute of Technology College of Osteopathic Medicine Old Westbury, New York Dimitrios Karamichos, PhD Professor of pharmaceutical sciences and pharmacology & neuroscience University of North Texas Health Science Center Fort Worth, Texas Reference 1. Alio JL, et al. Regenerative surgery of the corneal stroma for advanced keratoconus: 1-year outcomes. Am J Ophthalmol. 2019;203:53–68. Relevant disclosures Nattis: None Karamichos: None

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