Adding CXL to Excimer Procedures Safe, Effective at Three Years

Despite concerns about tissue removal in pathologically thin weakened corneas, PTK and topo-guided PRK plus CXL effectively halts disease progression.  Photo: Glaukos. Click image to enlarge. Corneal crosslinking (CXL) has evolved from a procedure solely aimed at halting progression to a multipurpose customized solution that could benefit corneal regularization and visual rehabilitation. However, the explosion of different protocols paradoxically has hindered the possibility of homogeneous comparative meta-analysis. Recent advances have greatly expanded the surgical options for patients with keratoconus, including “CXL-plus” procedures, which combine CXL with refractive techniques to stabilize the disease and remodel the cornea, improving visual outcomes. Among them, two popular strategies include phototherapeutic keratectomy (PTK) ablation to account for epithelial removal. A topography-guided photorefractive keratectomy (PRK) may be combined with PTK to allow for additional therapeutic improvement of corneal topographic irregularities.Valid concerns remain regarding the use of excimer laser to ablate corneal tissue in an already thin and weak pathological cornea. Also, valid consensual protocols to identify ideal candidates for each technique are still lacking, so researchers based in Portugal compared visual, refractive outcomes and disease progression in a range of one- to three-year follow-up, between two similar groups of patients with keratoconus performing either PTK plus CXL or topography-guided PRK plus CXL. They found that both protocols were safe and effective both at arresting the disease progression and providing visual improvement. PRK plus CXL, in particular, brings further corneal flattening, greater visual improvement and fewer corneal aberrations.This retrospective study, which was published in Cornea, included a total of 120 eyes from 120 patients, where 51.7% (n=62) were in the PTK plus CXL group and 48.3% (n=58) were in the PRK plus CXL group. Baseline characteristics were similar between groups, except for logMAR corrected distance visual acuity (CDVA) (PTK-CXL: 0.36; PRK-CXL: 0.47) and thinnest pachymetry (PTK-CXL: 436.58μm; PRK-CXL: 460.83µm).LogMAR CDVA significantly improved, with no differences between groups across all time points. However, mean improvement between the last follow-up and baseline was higher in the PRK plus CXL group (PTK-CXL: −0.12; PRK-CXL: −0.24). Maximum keratometry remained stable in the PTK plus CXL group (baseline: 60.82D; one year: 60.82D) but flattened in the PRK plus CXL group (baseline: 59.05D; one year: 54.45D). Total and higher-order aberrations improved in both groups, but spherical aberration and coma only improved after PRK plus CXL. All tomographic features remained stable across the follow-up.The researchers suggested that the improvement in the PTK plus CXL protocol was due to optimization of the classic epithelial mechanical debridement. The uniform 50μm ablation allows for some degree of anterior corneal stromal smoothening on the cone apex, where the epithelium is thinner, decreasing the disease-induced irregular astigmatism and leading to better visual outcomes.“This study demonstrates that both PTK and PTK plus topography-guided PRK combined with accelerated CXL stabilize keratoconus, improve vision and corneal aberrations and maintain a favorable safety profile,” the team wrote in their paper. “The topography-guided ablation further flattens the cornea, improves visual outcomes and does not compromise disease stabilization.”They concluded that “by stratifying patients based on their baseline CDVA and corneal thickness, we provide an actionable clinical algorithm: patients with thinner corneas or good baseline CDVA benefit from PTK plus CXL, whereas those with thicker corneas and unsatisfactory visual function are better candidates for topography-guided PRK plus CXL.”Click here for the journal source. Gil P, Gil JQ, Dias M, et al. Safety and efficacy of corneal crosslinking combined with phototherapeutic keratectomy with or without topography-guided photorefractive keratectomy. Cornea. June 10, 2025. [Epub ahead of print].