title: Photopic, Mesopic, and Scotopic Visual Acuity After 18 mW/cm2 Accelerated Corneal Cross-Linking.
abstract: OBJECTIVE
  One-year changes in uncorrected (UDVA) and corrected (CDVA) distance visual acuity under different lighting conditions after accelerated cross-linking (CXL) in patients with progressive keratoconus in comparison with nontreated cases.
  
  
  METHODS
  In this nonrandomized clinical trial, the sample included 50 eyes in the CXL group and 40 eyes in the control group. Visual acuity was tested under photopic (100 lux), mesopic (20 lux), and scotopic (0.5 lux) lighting conditions at 6 months and 1 year.
  
  
  RESULTS
  Changes in all studied variables were similar in the two groups (all P>0.05) after adjusting for age, but the 0.02±0.17 logMAR reduction in scotopic UDVA in the CXL group showed a difference of marginal significance compared with the control group (P=0.061). In cases with baseline UDVA≤20/40, 1-year adjusted results in the CXL and control groups were, respectively, 0.61±0.34 and 0.83±0.35 logMAR for photopic UDVA (P=0.021), 0.48±0.22 and 0.68±0.27 logMAR for mesopic UDVA (P=0.033), and 0.21±0.14 and 0.26±0.07 logMAR for mesopic CDVA (P=0.056). In those with baseline UDVA greater than 20/40, 1-year adjusted results in the CXL and control groups were, respectively, 0.12±0.20 and 0.06±0.10 logMAR for mesopic UDVA (P=0.034) and 0.15±0.18 and 0.07±0.06 logMAR for scotopic UDVA (P=0.024). Other vision indices showed no significant intergroup differences (all P>0.05).
  
  
  CONCLUSIONS
  Poor vision (UDVA≤20/40) keratoconus cases are more likely to achieve improved vision or a halt in its deterioration after CXL. In cases with good vision (UDVA>20/40), however, although further photopic vision impairment is halted, they may experience worse vision under mesopic and scotopic conditions.
authors.affiliation: Department of Epidemiology and Biostatistics (S.A., A.F.), School of Public Health, Tehran University of Medical Sciences, Tehran, Iran; Noor Ophthalmology Research Center (H.H., M.M., S.S.), Noor Eye Hospital, Tehran, Iran; Noor Research Center for Ophthalmic Epidemiology (E.J.), Noor Eye Hospital, Tehran, Iran; and Stein Eye Institute (S.M.), University of California, Los Angeles, CA.
authors.forename: Soheila
authors.initials: S
authors.lastname: Asgari
authors.forename: Hassan
authors.initials: H
authors.lastname: Hashemi
authors.forename: Mohammad
authors.initials: M
authors.lastname: Miraftab
authors.forename: Saied
authors.initials: S
authors.lastname: Shahhoseini
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Jafarzadhpur
authors.forename: Shiva
authors.initials: S
authors.lastname: Mehravaran
authors.forename: Akbar
authors.initials: A
authors.lastname: Fotouhi
mesh_terms: D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000494:pharmacology*; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents; D012029:Refraction, Ocular; D012189:Retrospective Studies; D012256:Riboflavin / Q000627:therapeutic use*; D014466:Ultraviolet Rays; D014792:Visual Acuity; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin