On September, 2019, Emilio Torres-Netto won the best poster prize (refractive section) at the ESCRS Annual meeting for his poster “Stromal bed smoothness after excimer laser surface ablation as a key element for the expression of inflammatory genes”. We are pleased to report that at the 2020 Winter ESCRS meeting in Marrakesh, Morocco, Dr. Torres-Netto won, once again, the same poster prize. Congratulations Dr. Torres-Netto!
The study he presented was a combination of the results of several years of basic research and data from a clinical study performed in Zurich, and it focused on improving how the laser interacts with the tissue with the objective of producing less inflammation during the procedure. This is important, as laser ablation of the corneal stroma – especially deep ablations, such as those required when treating high myopia and astigmatism – have the potential to cause significant corneal inflammation, and as part of the cornea’s wound healing response, corneal haze, which significantly slows the pace of patients’ visual recoveries.
Today, refractive surgeons use a drug called mitomycin C (MMC) to avoid developing haze, but this is a cytotoxic drug that intercalates with DNA and stops cells from proliferating, and the long-term consequences of using MMC are currently unknown.
Our researchers wanted to know whether using different laser ablation algorithms and optimised laser ablation profiles could alter the gene expression profiles of the ablated cornea, and they had a particular focus on genes that are involved with the inflammatory response.
What they found was that reductions in the inflammatory responses could be achieved by optimizing the laser ablation algorithms and energy settings, and that postoperative corneal smoothness appeared to be the key factor in regulating this immune response. To do so, they performed photorefractive keratectomy on rabbit corneas, using standard, high-fluence without optimization of corneal smoothness (OCS), low-fluence with OCS, and untreated controls, and examined the gene expression profiles 48 hours later using microarray gene expression analysis to identify genes that were expressed differently in treated and untreated corneas, followed by a technique called RT-PCR to validate those changes.
What Dr. Torres-Netto and his colleagues found that several pro-inflammatory genes were upregulated in the laser-treated corneas. Of note, they discovered that postoperative corneal smoothness was the key factor in inflammatory regulation – the smoother the cornea, the lower the inflammatory response, concluding that controlling stromal bed smoothness and thus, haze, may allow for deeper ablations, but also for the development of future ablation profiles that might broaden the indications of surface ablation to stromal depths currently only accessible with lamellar surgeries. What does this mean for patients? It is a simple message: surgeons should be able to correct more myopia using PRK that leaves the cornea smoother.