title: Nidek OPD-scan analysis of normal, keratoconic, and penetrating keratoplasty eyes.
abstract: OBJECTIVE
  To determine by wavefront analysis the difference between eyes considered normal, eyes diagnosed with keratoconus, and eyes that have undergone penetrating keratoplasty
  
  
  METHODS
  The Nidek OPD-Scan wavefront aberrometer was used to measure ocular aberrations out to the sixth Zernike order. One hundred and thirty eyes that were free of ocular pathology, 41 eyes diagnosed with keratoconus, and 8 eyes that had undergone penetrating keratoplasty were compared for differences in root mean square value. Three and five millimeter root mean square values of the refractive power aberrometry maps of the three classes of eyes were compared. Radially symmetric and irregular higher order aberration values were compared for differences in magnitude.
  
  
  RESULTS
  Root mean square values were lower in eyes free of ocular pathology compared to eyes with keratoconus and eyes that had undergone penetrating keratoplasty. The aberrations were larger with the 5-mm pupil. Coma and spherical aberration values were lower in normal eyes.
  
  
  CONCLUSIONS
  Wavefront aberrometry of normal, pathological, and eyes after surgery may help to explain the visual distortions encountered by patients. The ability to measure highly aberrated eyes allows an objective assessment of the optical consequences of ocular pathology and surgery. The Nidek OPD-Scan can be used in areas other than refractive surgery.
authors.affiliation: Midland Eye Institute, Solihull, UK. sunilshah@doctors.org.uk
authors.forename: Sunil
authors.initials: S
authors.lastname: Shah
authors.forename: Shehzad
authors.initials: S
authors.lastname: Naroo
authors.forename: Sarah
authors.initials: S
authors.lastname: Hosking
authors.forename: Doina
authors.initials: D
authors.lastname: Gherghel
authors.forename: Sanjay
authors.initials: S
authors.lastname: Mantry
authors.forename: Somnath
authors.initials: S
authors.lastname: Bannerjee
authors.forename: Katie
authors.initials: K
authors.lastname: Pedwell
authors.forename: Harkaran S
authors.initials: HS
authors.lastname: Bains
mesh_terms: D019781:Corneal Topography / Q000379:methods*; D006801:Humans; D007640:Keratoconus / Q000473:pathology*; D015948:Keratoplasty, Penetrating; D012029:Refraction, Ocular / Q000502:physiology; D014792:Visual Acuity