title: Intraocular lens exchange due to incorrect lens power.
abstract: OBJECTIVE
  To evaluate patients who had intraocular lens (IOL) exchange for unexpected postoperative refractive errors, determine the sources associated with the errors, and derive an empiric approach to estimating the power for IOL exchange.
  
  
  METHODS
  Retrospective review of interventional case series.
  
  
  METHODS
  Twenty-two eyes that underwent IOL exchange for correcting unexpected refractive errors after cataract surgery with IOL implantation were reviewed.
  
  
  METHODS
  All the IOLs for IOL exchange were placed in-the-bag. The same type of IOLs was used for original IOL implantation and IOL exchange in 91% (20/22) of eyes.
  
  
  METHODS
  Uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), refraction, and reasons for IOL exchange. The equation derived from refractive change and change in IOL power was developed to calculate IOL power for exchange.
  
  
  RESULTS
  Of the 22 cases, the identified reasons were keratometry errors in 5 (23%) and incorrect axial length (AL) determination in 3 (14%). In 3 other cases, a wrong IOL was implanted. After IOL exchange, 82% (18/22) of eyes were within +/-0.50 diopters (D) and 86% (19/22) within +/-1.00 D of emmetropia. Uncorrected visual acuity was 20/40 or better in 82% of eyes, and BSCVA was 20/40 or better in 95% (21/22) of eyes. The correlation between change of refraction and IOL power was significant (P<0.002).
  
  
  CONCLUSIONS
  Among the identified causes, incorrect corneal power determination was the most frequent reason for incorrect IOL power implantation, followed by error in AL measurement and inserting a wrong IOL. The pre-exchange refraction can be used theoretically to calculate the IOL power for exchange.
authors.affiliation: Eye Institute of Utah, Salt Lake City, Utah 84107, USA. georgejin@hotmail.com
authors.forename: George J C
authors.initials: GJ
authors.lastname: Jin
authors.forename: Alan S
authors.initials: AS
authors.lastname: Crandall
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Jones
mesh_terms: D002387:Cataract Extraction; D003315:Cornea / Q000473:pathology; D020878:Device Removal; D003951:Diagnostic Errors; D005139:Eyeglasses; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular / Q000009:adverse effects*; D019300:Medical Errors; D055095:Optics and Photonics; D012030:Refractive Errors / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D054140:Refractive Surgical Procedures; D012086:Reoperation; D012189:Retrospective Studies; D014792:Visual Acuity