title: Improving the preoperative prediction of the anterior pseudophakic distance for intraocular lens power calculation.
abstract: OBJECTIVE
  To establish a new formula for intraocular (IOL) power calculation.
  
  
  METHODS
  Private practice, Lynwood, California, USA.
  
  
  METHODS
  Retrospective observational and prospective evaluation.
  
  
  METHODS
  In this 2-part retrospective observational study followed by a prospective evaluation, the postoperative anterior pseudophakic distance (APD) was correlated with the ante-nucleus distance (AND), the nucleus thickness (NT) of the cataractous lens, and the axial length. An estimated APD (EAPD) equation was established and used prospectively in a new formula on eyes scheduled for cataract surgery.
  
  
  RESULTS
  Correlations were made in 90 operated eyes, and the EAPD equation was used in a new formula on 110 eyes scheduled for cataract surgery. Using the new IOL power formula, the median absolute error was 0.28 D with 82.7% of the eyes within ±0.50 D and 100% within ±1.00 D.
  
  
  CONCLUSIONS
  The new IOL power formula with its incorporated EAPD equation performed well.
  
  
  BACKGROUND
  H.J.S. has a pending patent on this system and method for determining IOL lens power.
authors.affiliation: From the Department of Ophthalmology (H.J. Shammas), Keck School of Medicine of the University of Southern California Los Angeles, Los Angeles, California, USA; Shammas Eye Medical Center (H.J. Shammas, M.C. Shammas), Lynwood, California, USA. Electronic address: jshammas@shammaseye.com.
authors.forename: H John
authors.initials: HJ
authors.lastname: Shammas
authors.affiliation: From the Department of Ophthalmology (H.J. Shammas), Keck School of Medicine of the University of Southern California Los Angeles, Los Angeles, California, USA; Shammas Eye Medical Center (H.J. Shammas, M.C. Shammas), Lynwood, California, USA.
authors.forename: Maya C
authors.initials: MC
authors.lastname: Shammas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000869:Anterior Eye Segment / Q000473:pathology*; D001699:Biometry / Q000379:methods; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D055095:Optics and Photonics; D018918:Phacoemulsification; D011182:Postoperative Care; D011446:Prospective Studies; D019591:Pseudophakia / Q000473:pathology*; D012189:Retrospective Studies