Contact lens wear and IOL power calculation before cataract surgery: a cautionary tale.

Purpose: 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.