Published: 2017-01-03

Our experience with Athens protocol - simultaneous topo-guided photorefractive keratectomy followed by corneal collagen cross linking for keratoconus

Shreyas Shah, Sujatha Mohan, Mohan Rajan, Bina John, Vini Badlani


Background: Corneal collagen cross linking (CXL) has become an established modality of treatment for progressive Keratoconus. Aim of the study was to analyze visual outcome, refractive status and changes in corneal curvature following simultaneous topography-guided photorefractive keratectomy (PRK) followed by corneal collagen cross-linking with riboflavin (C3R) for keratoconus in a tertiary eye care hospital.

Methods: All patients underwent manifest refraction, uncorrected visual acuity (UCVA), Best corrected visual acuity (BCVA), slit lamp examination, corneal topography, ultrasound pachymetry and fundus evaluation pre operatively. 39 eyes of 27 patients with keratoconus underwent simultaneous topo guided PRK + CXL were followed up upto 6 months.

Results: Mean UCVA improved from 0.81 log mar units pre-operatively to 0.43 log mar units at the end of 6 months. Preoperative BCVA was maintained or improved in 37 eyes (94.87%) and BCVA decreased by more than 1 line in 2 eyes (5.12%) post-operatively. The mean BCVA improved from 0.2 log mar units pre-operatively to 0.1 log mar units at the end of 6 months. The mean preoperative manifest refraction spherical equivalent reduced from -3.1±2.3D to -1.4±1.3D postoperatively. The mean steepest K reading decreased from 47.8±4.2D pre-op to 45±3.3D at the end of 6 month. Similarly, mean flat keratometry readings reduced significantly from 44.8±3.5D preoperatively to 42.2±2.8D at the last follow-up visit postoperatively.

Conclusions: Combined topo-guided PRK+CXL is an effective approach in treating patients with keratoconus. It biomechanically stabilizes the cornea, improves the corneal contour, reduces irregular astigmatism and offers a better quality of vision.


PRK, Zernike compensation, Athens protocol, Corneal collagen cross linking with riboflavin

Full Text:



Gu SF, Fan ZS, Wang LH, Tao XC, Zhang Y, Wang CQ, et al. A short-term study of corneal collagen cross-linking with hypo-osmolar riboflavin solution in keratoconic corneas. Int J Ophthalmol. 2015;8:94-7.

Spoerl E, Huhle M, Seiler T. Induction of cross-links in corneal tissue. Exp Eye Res. 1998;66:97-103.

Jankov Ii MR, Jovanovic V, Nikolic L, Lake JC, Kymionis G, Coskunseven E. Corneal collagen cross-linking. Middle East Afr J Ophthalmol. 2010;17:21-7.

Caporossi A, Baiocchi S, Mazzotta C, Traversi C, Caporossi T. Parasurgical therapy for keratoconus by riboflavin-ultraviolet type a rays induced cross-linking of corneal collagen: preliminary refractive results in an Italian study. J Cataract Refract Surg. 2006;32:837-45.

Wollensak G. Crosslinking treatment of progressive keratoconus: new hope. Curr Opin Ophthalmol. 2006;17:356-60.

Kymionis GD, Kontadakis GA, Kounis GA, Portaliou DM, Karavitaki AE, Magarakis M, et al. Simultaneous topography-guided PRK followed by corneal collagen cross-linking for keratoconus. J Refract Surg. 2009;25:S807-11.

Kanellopoulos AJ. Comparison of sequential vs same-day simultaneous collagen cross-linking and topography-guided PRK for treatment of keratoconus. J Refract Surg. 2009;25:S812-8.

Wagner H, Barr JT, Zadnik K. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study: methods and findings to date. Cont Lens Anterior Eye. 2007;30:223-32.

Rabinowitz YS. Keratoconus. Surv Ophthalmol. 1998;42:297-319.

Alessio G, L'Abbate M, Sborgia C, La Tegola MG. Photorefractive keratectomy followed by cross-linking versus cross-linking alone for management of progressive keratoconus: two-year follow-up. Am J Ophthalmol. 2013;155:54-65.e51.