Topographic corneal changes after collagen cross-linking in patients with corneal keratoconus
Hasan Razmjoo, Alireza Peyman, Kobra Nasrollahi, Hasan Salam, Najmeh Karbasi, Mohammad Reza Najarzadegan


Background: Corneal collagen cross-linking with riboflavin, also known as collagen cross-linking (CXL), involves the application of
riboflavin solution to the eye that is activated by illumination with ultraviolet A (UVA) light. We survey here the topographic corneal
changes one year after CXL in patients with corneal keratoconus. Materials and Methods: This prospective randomized clinical trial
study comprised 66 patients with progression of keratoconus during one year who were enrolled at Feiz University Referral Eye Center
in Isfahan. Before and after the operation, patients were examined with slit lamp and funduscopic examinations and measurement
of uncorrected visual acuity (UCVA), and best spectacle-corrected visual acuity (BSCVA) was done with a logarithm of minimal
angle of resolution (logMAR) scale. Corneal topographic and pachymetry values were derived from Orbscan II. The paired t-test
test was used for statistical analyses with SPSS software version 20 (SPSS Inc., Chicago, IL, USA). Results: All 66 patients completed
postoperative follow-up at 12 months. The mean age of the patients was 22.4 ± 5.4 years (range: 18-29 years). Thirty-six (54.55%)
subjects were men and 30 (45.45%) were women. The mean preoperative sphere was −2.66 ± 2.14 diopter (D), the mean cylinder
was −3.97 ± 2.29, and the mean spherical equivalent (SE) was −4.64 ± 2.56. Postoperatively, the mean sphere was −2.22 ± 2.57 D, the
mean cylinder was −3.60 ± 2.40 D, and SE was −4.02 ± 2.93 D (P = 0.037). SE also demonstrated a mean difference of 0.62 ± 0.37 D significantly (P = 0.006).The mean diameter of preoperative posterior best-fit sphere (BFS) was 6.33 ± 0.35mm (range: 5.51-7.73 mm) before operation, and it improved to 6.28 ± 0.34mm (range: 4.36-6.13 mm) after operation; the difference was significant (P = 0.039).
Conclusion: Our study showed a significant improvement in topographic corneal changes and refractive results in patients with corneal ectasia after CXL.

Key words: Collagen cross-linking, progressive keratoconus, ultraviolet irradiation

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