Topographic corneal changes after collagen cross-linking in patients with corneal keratoconus.
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.


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).


CONCLUSIONS
Our study showed a significant improvement in topographic corneal changes and refractive results in patients with corneal ectasia after CXL.
Department of Ophtalmology, Isfahan University of Medical Science, Feiz Hospital, Medical Students Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
Hasan
H
Razmjoo
Department of Ophtalmology, Isfahan University of Medical Science, Feiz Hospital, Medical Students Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
Alireza Peyman Kobra
AP
Nasrollahi
Department of Ophtalmology, Isfahan University of Medical Science, Feiz Hospital, Medical Students Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
Hasan
H
Salam
Department of Ophtalmology, Isfahan University of Medical Science, Feiz Hospital, Medical Students Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
Najmeh
N
Karbasi
Tehran Institute of Psychiatry-Faculity of Behavioural Sciences and Mental Health, Iran University of Medical Science, Tehran, Iran.
Mohammad Reza
MR
Najarzadegan
Collagen cross-linking; progressive keratoconus; ultraviolet irradiation