gms | German Medical Science

There is quite a large number of publications presenting both laboratory data, as well as clinical results of the effects of CXL with or without same-session corneal normalization with excimer ablation. The general consensus is that the intervention results in increased corneal biomechanical strength. The clinical reports indicate that CXL results in arrest of ectasia progression, in improvement of corneal keratometry, refraction and visual acuity, and in reduction of corneal irregularity; all that with infrequent post-operative complications. These outcomes encourage a number of motivating inquiries regarding the stability of the induced changes. For example, what is the long-term stability? Is the cornea ‘fixed’ after the operation, and if not, are the resulting changes regressing towards a steeper or a flatter cornea? Does the cornea maintain its thickness postoperatively?

These questions are even more pertinent in the case of the Athens Protocol procedure, since the intervention is preceded by a partial surface ablation, which may sound as an unorthodox approach for a keratoconic eye. However, the goal of using topography-guided ablation is to normalize the corneal surface and thus help improve visual rehabilitation to a step beyond a simple CXL would provide. The concept of ablating a thin, ectatic cornea usually alarms surgeons and patients alike. This study aims to address some of the above questions by evaluation of a very large number of cases over an extended amount of time, when compared to the current peer-reviewed literature. These numbers and follow-up is still quite large and permits sensitive statistical analysis with confident conclusion in post-operative efficacy.

We monitored best-spectacle corrected and uncorrected visual acuity changes, and for the quantitative assessment, we chose to standardize on one screening device, the Pentacam, and to focus on the key parameters of keratometry, pachymetry, and anterior surface indices. Changes in these anterior surface indices may provide a more comprehensive analysis of the changes in the keratometry and visual function after CXL. All of the above metrics reflect the corneal changes induced by the procedure and describe the postoperative progression. Our results in the present study indicate that the apparent disadvantage of thinning the cornea is complemented by a documented long-term vision-rehabilitating improvement and synergy from the CXL component.