title: Changes in visual function under mesopic and photopic conditions after intrastromal corneal ring segment implantation for different stages of keratoconus.
abstract: OBJECTIVE
  To analyze and compare the changes in visual function under mesopic and photopic conditions in different stages of keratoconus before and after Keraring intrastromal corneal ring segment (ICRS) implantation.
  
  
  METHODS
  Clinico San Carlos Hospital and Faculty of Optics and Optometry, Complutense University, Madrid, Spain.
  
  
  METHODS
  Case series.
  
  
  METHODS
  Keratoconic eyes were evaluated under mesopic (0.1 to 0.2 candelas [cd]/m(2)) and photopic (85 cd/m(2)) conditions. LogMAR high-contrast corrected distance visual acuity (CDVA) and low-contrast CDVA were assessed using the Bailey-Lovie test and logarithmic contrast sensitivity, using the Pelli-Robson test.
  
  
  RESULTS
  The study evaluated 12 eyes with stage I keratoconus, 21 eyes with stage 2, and 14 eyes with stage 3. The mean change in photopic high-contrast CDVA was 0.16 logMAR ± 0.20 (SD) (P<.00001). Photopic low-contrast CDVA increased by a mean of 0.14 ± 0.26 logMAR (P=.0005), photopic contrast sensitivity by a mean of 0.09 ± 0.22 logMAR (P=.005), and mesopic high-contrast CDVA by a mean of 0.10 ± 0.26 logMAR (P=.03). There were no significant differences between stages. Surgery did not affect the mean changes in mesopic low-contrast CDVA or mesopic contrast sensitivity for any stage.
  
  
  CONCLUSIONS
  Implantation of ICRS in keratoconic eyes increased photopic high-contrast CDVA, low-contrast CDVA, and contrast sensitivity. Under low luminance, the mean changes in high-contrast CDVA, low-contrast CDVA, and contrast sensitivity did not worsen after ICRS implantation performed 5.0 mm from the visual axis, despite the rings being partially superimposed on the mydriatic pupil.
authors.affiliation: Applied Vision Research Group, Faculty of Optics and Optometry, Complutense University, Madrid, Spain. jcarball@opt.ucm.es
authors.forename: Jesús
authors.initials: J
authors.lastname: Carballo
authors.forename: María Cinta
authors.initials: MC
authors.lastname: Puell
authors.forename: Ricardo
authors.initials: R
authors.lastname: Cuiña
authors.forename: José María
authors.initials: JM
authors.lastname: Vázquez
authors.forename: José M
authors.initials: JM
authors.lastname: Benitez-del-Castillo
mesh_terms: D000293:Adolescent; D000328:Adult; D055253:Color Vision / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000601:surgery*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000145:classification / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D055255:Mesopic Vision / Q000502:physiology*; D008875:Middle Aged; D011446:Prospective Studies; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D054140:Refractive Surgical Procedures / Q000379:methods; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult