title: Assessment of the tomographic values in keratoconic eyes after collagen crosslinking procedure.
abstract: OBJECTIVE
  This study aimed to investigate the differences in values of K1 and K2 readings, the central corneal thickness (PAH) before the collagen crosslinking procedure (CXL) and 3, 6, 12 months later.
  
  
  METHODS
  64 eyes were evaluated in retrospective cross sectional study. The corneal biomechanical parameters were taken with WaveLight Allegro Oculyzer produced by Alcon before the CXL, 3,6, 12 months after the procedure. The curvature of K1 reading and K2 reading were taken and the central corneal thickness were considered due to the time after CXL.
  
  
  RESULTS
  The value of K1 reading before the treatment was 48.8 diopters (D) (46.65-50.50) and was statistically significant lower comparing to the value of K1 3 months after the collagen CXL procedure 46.30 D (43.57-49.45) (p=0.0006), K1 reading one year post collagen CXL procedure was 47.20 D (44.35-50.07) (p=0.002). The value of K2 reading before the collagen CXL procedure was 52.65 D (47.55-54.72), 3 months after the procedure was 51.4 (45.05-54.0), 6 months later 48.55 D (47.20-50.62), 12 months later 51.30 D (47.22-54.77). There is statistically significant lower value of K2 reading 6 months after the treatment comparing to the values 3 months postoperatively (p=0.014). However there is significantly lower values of K2 reading 12 months postoperatively comparing to preoperative period (p=0.006). The value of central corneal thickness preoperative was 431.0 microns (398.0-446.25), 3 months after collagen CXL procedure was 373.50 microns (363.25-430.75), 6 months later 435.0 microns (360.0-464.75), 12 months after the CXL procedure was 429.50 microns (357.75-496.25). There is statistically significant lower values of central corneal thickness 3 months after collagen CXL treatment comparing to the central corneal thickness preoperative (p<0.005). There is statistically significant lower values of pachymetry 12 months after the CXL procedure comparing to the values 6 months later (p=0.036) and those preoperativelly (p=0.032). There is no statistically significant difference in the values of central corneal thickness in the period from 3 and 6 months postoperatively.
  
  
  CONCLUSIONS
  After riboflavin-UVA CXL in eyes with keratokonus there was significant decrease in central corneal thickness 3 and 6 months after the procedure and the thickness is almost the same 12 months. However, K2 (Kmax) reading is significantly changed 3 and 6 months later and is followed by changing of K1 reading.
authors.affiliation: Eye Polyclinic "Dr. Sefic", Sarajevo, Bosnia and Herzegovina.
authors.forename: Sanja
authors.initials: S
authors.lastname: Sefic Kasumovic
authors.affiliation: Eye Clinic, Clinical Center University of Sarajevo, Bosnia and Herzegovina.
authors.forename: Adisa
authors.initials: A
authors.lastname: Racic-Sakovic
authors.affiliation: Eye Polyclinic "Dr. Sefic", Sarajevo, Bosnia and Herzegovina.
authors.forename: Aida
authors.initials: A
authors.lastname: Kasumovic
authors.affiliation: Public Health Centre, Tuzla, Bosnia and Herzegovina.
authors.forename: Suzana
authors.initials: S
authors.lastname: Pavljasevic
authors.affiliation: Cantonal hospital "Dr. Irfan Ljubijankic", Bihac, Bosnia and Herzegovina.
authors.forename: Belkisa
authors.initials: B
authors.lastname: Duric-Colic
authors.affiliation: "Public Health Care Institution Doboj-Jug, Matuzici", Bosnia and Herzegovina.
authors.forename: Emir
authors.initials: E
authors.lastname: Cabric
authors.affiliation: University Clinical Center, Banjaluka, Bosnia and Herzegovina.
authors.forename: Milka
authors.initials: M
authors.lastname: Mavija
authors.affiliation: Department of Human Physiology, Faculty of Medicine, University of Sarajevo, Bosnia and Herzegovina.
authors.forename: Orhan
authors.initials: O
authors.lastname: Lepara
authors.affiliation: Laser Fokus Centre for Eye Microsurgery, Beograd, Serbia.
authors.forename: Mirko
authors.initials: M
authors.lastname: Jankov
mesh_terms: D000328:Adult; D003094:Collagen / Q000187:drug effects / Q000378:metabolism*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000000981:diagnostic imaging / Q000188:drug therapy*; D008297:Male; D010778:Photochemotherapy / Q000379:methods; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D012189:Retrospective Studies; D012256:Riboflavin / Q000627:therapeutic use*; D041623:Tomography, Optical Coherence; D014467:Ultraviolet Therapy / Q000379:methods; D055815:Young Adult
chemical_list: D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin
keywords: K1, K2 readings; central corneal thickness; collagen crosslinking; keratokonus; riboflavin; ultraviolet irradiation