title: White-to-white corneal diameter differences in moderately and highly myopic eyes: partial coherence interferometry versus scanning-slit topography.
abstract: OBJECTIVE
  To evaluate the differences between Orbscan scanning-slit topography and IOLMaster partial coherence interferometry (PCI) white-to-white (WTW) measurements in moderately and highly myopic eyes.
  
  
  METHODS
  IOBA-Eye Institute, University of Valladolid, Spain.
  
  
  METHODS
  Comparative case series.
  
  
  METHODS
  Myopic eyes were divided according to the degree of myopia as follows: Group 1 (<6.00 diopters [D]), Group 2 (between 6.00 D and 12.00 D), and Group 3 (>12.00 D). The WTW distance was measured with the scanning-slit topography and PCI devices.
  
  
  RESULTS
  The study enrolled 328 eyes (64 subjects). The mean WTW in all eyes was 0.50 mm ± 0.26 (SD), lower with scanning-slit topography (11.69 ± 0.37 mm) than with PCI (12.19 ± 0.40 mm) (P<.01, paired t test). A low mean WTW was found in Group 2 (11.65 ± 0.34 and 12.15 ± 0.36 mm, scanning-slit topography and PCI, respectively) and Group 3 (11.51 ± 0.36 and 12.05 ± 0.46 mm, respectively) compared with Group 1 (11.79 ± 0.38 and 12.26 ± 0.40 mm, respectively) (P<.03, analysis of variance with Games-Howell correction). There was a low statistically significant relationship between WTW and spherical equivalent (SE) with both devices.
  
  
  CONCLUSIONS
  Eyes with moderate and high degrees of myopia had lower WTW diameters than eyes with low spherical equivalent myopia measured with both devices. Scanning-slit topography provided less WTW distance than PCI in myopic eyes; thus, the devices are not clinically interchangeable.
authors: IOBA-Eye Institute, Department of Theoretical Physics, Atomic Physics and Optics, School of Optometry, University of Valladolid, Valladolid, Spain. raul@ioba.med.uva.es
authors: Raul
authors: R
authors: Martin
authors: Sara
authors: S
authors: Ortiz
authors: Ana
authors: A
authors: Rio-Cristobal
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography / Q000379:methods; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D007368:Interferometry / Q000379:methods; D008027:Light; D008297:Male; D008875:Middle Aged; D047728:Myopia, Degenerative / Q000145:classification / Q000473:pathology*; D009929:Organ Size; D015203:Reproducibility of Results; D055815:Young Adult