title: Topographic, corneal wavefront, and refractive outcomes 2 years after collagen crosslinking for progressive keratoconus.
abstract: OBJECTIVE
  The aim was to report the corneal higher-order aberrations (HOA), the topographic metrics, and the visual and refractive outcomes 2 years after performing collagen crosslinking (CXL) for progressive keratoconus. The correlation among corneal HOAs, topographic metrics, and visual acuity changes was also investigated.
  
  
  METHODS
  This is a prospective case series involving 42 eyes from 32 patients with progressive keratoconus treated with CXL. The main outcomes measured at baseline and 6, 12, and 24 months after treatment were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive changes, topographic data, and corneal aberrations.
  
  
  RESULTS
  Two years after CXL treatment, the UDVA (P < 0.001), CDVA (P < 0.001), and spherical equivalent (P = 0.048) improved significantly. The corneal topographic data revealed significant decreases in apical keratometry (P < 0.001), differential keratometry (P = 0.031), and central keratometry (P = 0.003) compared with the baseline measurements. Aberration analyses revealed a significant reduction in coma (P = 0.016), trefoil (P = 0.018), secondary astigmatism (P < 0.001), quatrefoil (P = 0.031), secondary coma (P < 0.001), and secondary trefoil (P = 0.001). Corneal HOA (except quatrefoil) demonstrated a significant correlation with postoperative CDVA; the highest correlations were for coma (rho = 0.703, P < 0.001), secondary astigmatism (rho = 0.519, P = 0.001), and total HOA (rho = 0.487, P = 0.001). However, the corneal HOA changes were not statistically associated with improved visual acuity. After treatment, the reduction in apical keratometry was the only variable that correlated with the improvement in the CDVA (rho = 0.319, P = 0.042).
  
  
  CONCLUSIONS
  After 2 years, CXL was found to be effective in improving the UDVA, CDVA, topographic metrics, and most corneal HOAs in eyes with progressive keratoconus. A significant reduction was observed in apical keratometry, and this reduction directly correlated with an improvement in visual acuity.
authors.affiliation: *Sadalla Amin Ghanem Eye Hospital, Joinville, Santa Catarina, Brazil; †Department of Ophthalmology, University of São Paulo, São Paulo, Brazil; and ‡Department of Ophthalmology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Ramon C
authors.initials: RC
authors.lastname: Ghanem
authors.forename: Marcony R
authors.initials: MR
authors.lastname: Santhiago
authors.forename: Thais
authors.initials: T
authors.lastname: Berti
authors.forename: Marcelo V
authors.initials: MV
authors.lastname: Netto
authors.forename: Vinícius C
authors.initials: VC
authors.lastname: Ghanem
mesh_terms: D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000378:metabolism*; D019781:Corneal Topography; D057108:Corneal Wavefront Aberration / Q000188:drug therapy / Q000473:pathology; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D012256:Riboflavin / Q000627:therapeutic use; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin