title: Comparison of the Pentacam equivalent keratometry reading and IOL Master keratometry measurement in intraocular lens power calculations.
abstract: BACKGROUND
  To compare the accuracy of the Pentacam Holladay equivalent keratometry readings with the IOL Master 500 keratometry in calculating intraocular lens power.
  
  
  METHODS
  Non-randomized, prospective clinical study conducted in private practice.
  
  
  METHODS
  Forty-five consecutive normal patients undergoing cataract surgery.
  
  
  METHODS
  Forty-five consecutive patients had Pentacam equivalent keratometry readings at the 2-, 3 and 4.5-mm corneal zone and IOL Master keratometry measurements prior to cataract surgery. For each Pentacam equivalent keratometry reading zone and IOL Master measurement the difference between the observed and expected refractive error was calculated using the Holladay 2 and Sanders, Retzlaff and Kraff theoretic (SRKT) formulas.
  
  
  METHODS
  Mean keratometric value and mean absolute refractive error.
  
  
  RESULTS
  There was a statistically significantly difference between the mean keratometric values of the IOL Master, Pentacam equivalent keratometry reading 2-, 3- and 4.5-mm measurements (P < 0.0001, analysis of variance). There was no statistically significant difference between the mean absolute refraction error for the IOL Master and equivalent keratometry readings 2 mm, 3 mm and 4.5 mm zones for either the Holladay 2 formula (P = 0.14) or SRKT formula (P = 0.47). The lowest mean absolute refraction error for Holladay 2 equivalent keratometry reading was the 4.5 mm zone (mean 0.25 D ± 0.17 D). The lowest mean absolute refraction error for SRKT equivalent keratometry reading was the 4.5 mm zone (mean 0.25 D ± 0.19 D). Comparing the absolute refraction error of IOL Master and Pentacam equivalent keratometry reading, best agreement was with Holladay 2 and equivalent keratometry reading 4.5 mm, with mean of the difference of 0.02 D and 95% limits of agreement of -0.35 and 0.39 D.
  
  
  CONCLUSIONS
  The IOL Master keratometry and Pentacam equivalent keratometry reading were not equivalent when used only for corneal power measurements. However, the keratometry measurements of the IOL Master and Pentacam equivalent keratometry reading 4.5 mm may be similarly effective when used in intraocular lens power calculation formulas, following constant optimization.
authors.affiliation: Wangaratta, Victoria, Australia.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Karunaratne
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058452:Axial Length, Eye / Q000033:anatomy & histology*; D003315:Cornea / Q000033:anatomy & histology* / Q000502:physiology; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D055095:Optics and Photonics; D018918:Phacoemulsification; D011446:Prospective Studies; D015203:Reproducibility of Results; D014792:Visual Acuity / Q000502:physiology
keywords: IOL Master keratometry; Pentacam; Scheimpflug; equivalent keratometry reading