title: Optical and ultrasound measurement of axial length and anterior chamber depth for intraocular lens power calculation.
abstract: OBJECTIVE
  To evaluate the precision, reproducibility, and applicability of an optical method based on partial coherence interferometry for intraocular lens (IOL) power calculation.
  
  
  METHODS
  Ultrasound laboratory of a university eye hospital.
  
  
  METHODS
  A prospective comparison of measurements made by the IOLMaster optical instrument (Carl Zeiss) and Ultrascan Digital 2000 contact ultrasound A-scan (Alcon) for IOL calculations was performed. Examined were 255 eyes of 134 persons (204 phakic, 47 pseudophakic, and 4 aphakic). The mean age of the patients was 67.9 years (range 7 to 94 years).
  
  
  RESULTS
  The IOLMaster measurements were successful in more than 80% of cases: in 82%, 99%, and 99% for axial length (AL), anterior chamber depth (ACD), and keratometry measurements, respectively. The reproducibility of the AL and ACD measurements was very high (coefficient of variation 0.13% and 2.20%, respectively). The AL and ACD values were significantly larger with the IOLMaster (P <.001) than with the Ultrascan Digital 2000. The correlation between ultrasound and optical AL measurements was high (r = 0.985; P <.001); however, there was no correlation between ACD measurements (r = 0.079; P =.397). The corneal refractive power measurements of a Javal-type keratometer and the IOLMaster were highly correlated (r = 0.955; P <.001), with a mean difference of 0.2 diopter.
  
  
  CONCLUSIONS
  The results show that measurements for IOL calculation are easy and precise with the optical method. It is a noncontact method, so no anesthesia is needed and there is no risk of infection.
authors.affiliation: 1st Department of Ophthalmology, Semmelweis University, Budapest, Hungary. nj@szem1.sote.hu
authors.forename: János
authors.initials: J
authors.lastname: Németh
authors.forename: Orsolya
authors.initials: O
authors.lastname: Fekete
authors.forename: Norbert
authors.initials: N
authors.lastname: Pesztenlehrer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000000981:diagnostic imaging* / Q000473:pathology*; D001035:Aphakia / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D002648:Child; D003315:Cornea / Q000503:physiopathology; D005260:Female; D006801:Humans; D007368:Interferometry; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D055095:Optics and Photonics; D011446:Prospective Studies; D019591:Pseudophakia / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D012029:Refraction, Ocular; D015203:Reproducibility of Results; D014463:Ultrasonography