Current Protocols of Corneal Collagen Cross-Linking: Visual, Refractive, and Tomographic Outcomes

To study the effect of different protocols of collagen cross-linking on visual, refractive, and tomographic parameters in patients with progressive keratoconus.

Prospective randomized interventional study.

In this study, 138 eyes of 138 patients with progressive keratoconus underwent corneal collagen cross-linking (CXL). Following detailed preoperative examination, Group I underwent conventional cross-linking (36 patients, 3 mW/cm(2) for 30 min); Group II (36 patients, 9 mW/cm(2) for 10 min), Group III (33 patients, 18 mW/cm(2) for 5 min), and Group IV (33 patients, 30 mW/cm(2) for 3 min) underwent accelerated cross-linking. Changes in corrected distance visual acuity (CDVA), spherical equivalent (SE), flat keratometry, steep keratometry, thinnest pachymetry, specular microscopy, and demarcation line were studied at 6 and 12 months.

Improvement in the mean CDVA and SE were statistically significant in all groups except Group IV (P = .15 at 6 months, P = .17 at 12 months), with Group III (P = .01 at 6 and 12 months) showing the best results. Flattening of steep and flat keratometry was significant in Groups I (P = .01) and II (P = .01) as compared to the other groups. There was no significant difference in the pachymetry or specular microscopy in any of the groups. Groups I and II demonstrated a good demarcation line when compared to other groups.

Conventional CXL (Group I) and accelerated CXL with irradiations of 9 mW/cm(2) (Group II) and 18 mW/cm(2) (Group III) showed better visual, refractive, and tomographic improvements at the end of 12 months.