Evidence supports 'Athens Protocol'

March 15, 2011

Simultaneous topography-guided partial PRK with cornea collagen crosslinking offers a safe and effective approach for normalizing the cornea and enhancing visual function in eyes with ectatic conditions.

Dr. Kanellopoulos discussed the importance of combining CXL with a technique to address highly irregular astigmatism in the management of eyes with keratoconus and postLASIK ectasia.

In addition, he presented theoretical and clinical evidence supporting the use of his "Athens Protocol" where CXL and topography-guided surface ablation are performed in the same session rather than sequentially.

"Safety with our combination approach has been favorable as well," he added. "Although postoperative haze and delayed epithelial healing have occurred, these have been minor complications in a small number of eyes within our very large series."

Meeting visual rehabilitation needs

Although the efficacy of CXL for stabilizing keratectasia is well established, and the procedure also causes some corneal flattening, significant residual astigmatism limiting contact lens wear may be a persistent problem for some patients.

This situation creates an indication to perform the partial topography-guided partial PRK, Dr. Kanellopoulos said.

"I realize surface ablation in a keratoconic eye may sound unorthodox, but the goal of our treatment using the topography-guided software is to normalize the corneal surface and improve best corrected acuity," he said. "This is a therapeutic procedure, not a refractive one. In fact, some eyes turn out more myopic postoperatively, but have significant regularity and BSCVA improvement. We have chosen the ablation to remove no more than 50 µm of stroma and, at most, it treats 2 to 2.5 D of astigmatism and up to 1 D of myopia."

The Athens Protocol begins with a 6.5-mm PTK to remove 50 µm of epithelium. Then, the topography-guided partial PRK is performed followed by mitomycin-C application (0.02% for 20 seconds) and the CXL procedure. The excimer laser ablation resembles part of a hyperopic treatment. It is performed using a 5.5-mm effective optical zone and targets steepening of the area adjacent to the cone in an attempt to regularize the corneal surface.