title: Estimation of effective lens position using a method independent of preoperative keratometry readings.
abstract: OBJECTIVE
  To evaluate the validity of a keratometry (K)-independent method of estimating effective lens position (ELP) before phacoemulsification cataract surgery.
  
  
  METHODS
  Institute of Eye Surgery, Whitfield Clinic, Waterford, Ireland.
  
  
  METHODS
  Evaluation of diagnostic test or technology.
  
  
  METHODS
  The anterior chamber diameter and corneal height in eyes scheduled for cataract surgery were measured with a rotating Scheimpflug camera. Corneal height and anterior chamber diameter were used to estimate the ELP in a K-independent method (using the SRK/T [ELP(rs)] and Holladay 1 [ELP(rh)] formulas).
  
  
  RESULTS
  The mean ELP was calculated using the traditional (mean ELP(s) 5.59 mm ± 0.52 mm [SD]; mean ELP(h) 5.63 ± 0.42 mm) and K-independent (mean ELP(rs) 5.55 ± 0.42 mm; mean ELP(rh) ± SD 5.60 ± 0.36 mm) methods. Agreement between ELP(s) and ELP(rs) and between ELP(h) and ELP(rh) were represented by Bland-Altman plots, with mean differences (± 1.96 SD) of 0.06 ± 0.65 mm (range -0.59 to +0.71 mm; P=.08) in association with ELP(rs) and -0.04 ± 0.39 mm (range -0.43 to +0.35 mm; P=.08) in association with ELP(rh). The mean absolute error for ELP(s) versus ELP(rs) estimation and for ELP(h) versus ELP(rh) estimation was 0.242 ± 0.222 mm (range 0.001 to 1.272 mm) and 0.152 ± 0.137 mm (range 0.001 to 0.814 mm), respectively.
  
  
  CONCLUSIONS
  This study confirms that the K-independent ELP estimation method is comparable to traditional K-dependent methods and may be useful in post-refractive surgery patients.
authors.affiliation: Department of Ophthalmology, Waterford Regional Hospital, Institute of Eye Surgery, Dublin, Ireland. iandooley@eustace.net
authors.forename: Ian
authors.initials: I
authors.lastname: Dooley
authors.forename: Sofia
authors.initials: S
authors.lastname: Charalampidou
authors.forename: John
authors.initials: J
authors.lastname: Nolan
authors.forename: James
authors.initials: J
authors.lastname: Loughman
authors.forename: Laura
authors.initials: L
authors.lastname: Molloy
authors.forename: Stephen
authors.initials: S
authors.lastname: Beatty
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000473:pathology*; D001699:Biometry; D019923:Capsulorhexis; D002386:Cataract / Q000473:pathology*; D003315:Cornea / Q000473:pathology*; D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008875:Middle Aged; D018918:Phacoemulsification; D010781:Photography; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology