title: Contact lens wear and IOL power calculation before cataract surgery: a cautionary tale.
abstract: OBJECTIVE
  To present a case of erroneous corneal measurements, which led to inaccurate predicted intraocular lens (IOL) power.
  
  
  METHODS
  A 60-year-old woman underwent preoperative assessment for cataract surgery. The predicted IOL power was 19.5 D.
  
  
  RESULTS
  Repeated biometry led to different measurements and an 11.0-D powered IOL was inserted. The predicted IOL power was incorrect, as the patient had worn contact lenses during the preoperative assessment.
  
  
  CONCLUSIONS
  This case demonstrates that errors can occur, and it is essential to fully understand the principles of biometry and the refractive issues of cataract surgery to avoid postoperative refractive errors.
authors.affiliation: Department of Ophthalmology, Musgrove Park Hospital, United Kingdom. danqbnguyen@hotmail.com
authors.forename: D Q
authors.initials: DQ
authors.lastname: Nguyen
authors.forename: K N
authors.initials: KN
authors.lastname: Hakin
mesh_terms: D002387:Cataract Extraction; D003261:Contact Lenses; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular / Q000295:instrumentation; D007910:Lenses, Intraocular; D008875:Middle Aged; D011300:Preoperative Care / Q000379:methods*; D011379:Prognosis; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000517:prevention & control*