Topography-Gueded Photorefractive Keratectomy Combined With Crosslinking In Patiens With Keratoconus (Athens Protocol)

The purpose of the study was to determine the effectiveness of topographic PRK in combination with crosslinking in patients with stable keratoconus

The study included 6 eyes (8 patients) with stable keratoconus who had not previously undergone crosslinking. Uncorrected visual acuity (UCVA), keratometry results, and complications were assessed at 1, 3, 6, and 12 months postoperatively. Eligibility criteria: Age (over 30 years)

The laser ablation procedure is based on the individual characteristics of the patient's cornea, including its asphericity and high-order aberrations, when planning the laser ablation. 

The first step was a single-stage transepithelial topographically guided PRK with a planned optical zone of 6.5 mm plus a transition zone of 0.75 mm. Following ablation, mitomycin C was applied.

The second step was accelerated crosslinking. If the residual corneal stromal thickness was greater than 400 µm, pulsed irradiation of the cornea^ was performed in a 7 mm zone with ultraviolet light for 5 minutes at a power of 18 mW/cm2 and an energy of 5.4 J. Then, a 5 mm zone was irradiated for 3 minutes 20 seconds at a power of 18 mW/cm2 and an energy of 5.4 J. The final 3 mm zone (the apex of the cone) was irradiated for 4 minutes 10 seconds with the same energy. The total irradiation time was 12 minutes.

Sphere, cylinder, and Kmax values ​​decreased in all patients after treatment. In addition, statistically significant reductions were observed in total higher-order aberrations (RMS), coma RMS, and spherical RMS. After 12 months, mean uncorrected visual acuity (UCVA) improved from 0.2 ± 0.18 to 0.5 ± 0.12, and corrected visual acuity (CVA) improved from 0.4 ± 0.142 to 0.8 ± 0.078. Mean flat, steep, and maximum keratometry values ​​were significantly reduced by 2.13 and 4.54 diopters, respectively, at the final follow-up examination. One patient experienced haze, which resolved within 2 months.

Topographically guided PRK in patients with keratoconus can be an effective procedure for carefully selected indications—most often in combination with crosslinking and in stable cases. This is not a "curative" procedure in the classic sense, but rather a method for enhancing visual function in carefully selected patients. The combined procedure of topographically guided PRK and accelerated crosslinking (CXL) appears to be a promising treatment for keratoconus. It reduces high-order aberrations, stabilizes corneal shape, and improves visual function.