title: Outcomes of corneal crosslinking for central and paracentral keratoconus.
abstract: BACKGROUND
  The aim of the study was to compare the therapy of corneal collagen crosslinking (CXL) for central and paracentral keratoconus.
  
  
  METHODS
  64 eyes of 43 central keratoconus patients whose highest power of the cornea located in the central 3 mm zone and 24 eyes of 16 paracentral keratoconus patients whose highest power located out of the central 3 mm zone received standard corneal CXL were included. Maximum keratometry (Kmax) and astigmatism according to topography, uncorrected distant visual acuity (UDVA), corrected distant visual acuity (CDVA) were studied preoperatively and 2 years postoperatively.
  
  
  RESULTS
  Central group: Preoperative UDVA and CDVA were 0.9 ± 0.4 and 0.5 ± 0.4 logMAR, respectively. At 2 years, UDVA and CDVA significantly improved to 0.8 ± 0.4 and 0.4 ± 0.3 logMAR(P < 0.01). Preoperative Kmax and astigmatism were 61.5 ± 14.7 diopter (D) and 4.0 ± 2.9 D, respectively. At 2 years, Kmax and astigmatism significantly decreased to 57.0 ± 10.4 and 3.0 ± 2.2 D (P < 0.01). Paracentral group: preoperative UDVA and CDVA were 0.8 ± 0.7 and 0.2 ± 0.4 logMAR, respectively. At 2 years, UDVA significantly improved to 0.4 ± 0.4 logMAR(P < 0.01), whereas CDVA remained 0.2 ± 0.3 logMAR(P > 0.05). Preoperative Kmax and astigmatism were 50.3 ± 5.3 and 2.4 ± 1.7 D, respectively. At 2 years, Kmax significantly decreased to 48.8 ± 4.6 (P < 0.01), whereas astigmatism remained 2.2 ± 1.8 D (P > 0.05).
  
  
  CONCLUSIONS
  This study indicated that CXL was more effective for central keratoconus than paracentral keratoconus.
authors.affiliation: Department of Ophthalmology, The First People's Hospital of Jining Affiliated to Jining Medical College, Jining Department of Ophthalmology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong Province, China.
authors.forename: Mingxia
authors.initials: M
authors.lastname: Tian
authors.forename: Ping
authors.initials: P
authors.lastname: Ma
authors.forename: Weiyan
authors.initials: W
authors.lastname: Zhou
authors.forename: Jie
authors.initials: J
authors.lastname: Feng
authors.forename: Guoying
authors.initials: G
authors.lastname: Mu
mesh_terms: D000293:Adolescent; D000328:Adult; D001251:Astigmatism; D002648:Child; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000628:therapy*; D008297:Male; D017319:Photosensitizing Agents / Q000008:administration & dosage*; D011446:Prospective Studies; D012256:Riboflavin / Q000008:administration & dosage*; D016896:Treatment Outcome; D014467:Ultraviolet Therapy; D055815:Young Adult
chemical_list: D017319:Photosensitizing Agents; D012256:Riboflavin