title: Accuracy of optical biometry combined with Placido disc corneal topography for intraocular lens power calculation.
abstract: OBJECTIVE
  To investigate the accuracy of a new optical biometer for intraocular lens (IOL) power calculation in eyes undergoing cataract surgery.
  
  
  METHODS
  Consecutive eyes of patients undergoing cataract surgery with the same IOL model were enrolled in a prospective cohort study. Axial length (AL) and corneal power were measured with an optical biometer based on optical low-coherence interferometry and Placido-disc corneal topography. IOL power was calculated with the Hoffer Q, Holladay 1 and SRK/T formulas. For each formula the lens constant was optimized in retrospect in order to achieve a mean prediction error (PE) of zero (difference between the predicted and the postoperative refraction). Median absolute error (MedAE) and percentage of eyes with PE ±0.50 D were calculated.
  
  
  RESULTS
  Seventy-four eyes of 74 cataract patients were enrolled. The MedAE was 0.25 D with all formulas. A PE within ±0.50 D was obtained in 89.04% of cases with the Hoffer Q and SRK/T formulas, and in 87.67% of cases with the Holladay 1 formula.
  
  
  CONCLUSIONS
  The optical biometer investigated in the present study provides accurate measurements for IOL power calculation.
authors.affiliation: Fondazione G.B. Bietti IRCCS, Rome, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Savini
authors.affiliation: Stein Eye Institute, University of California, Los Angeles, CA, United States of America.|St. Mary's Eye Center, Santa Monica, CA, United States of America.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Hoffer
authors.affiliation: Studio Oculistico d'Azeglio, Bologna, Italy.|Scientific Institute San Raffaele, Milan, Italy.
authors.forename: Piero
authors.initials: P
authors.lastname: Barboni
authors.affiliation: Studio Oculistico d'Azeglio, Bologna, Italy.
authors.forename: Nicole
authors.initials: N
authors.lastname: Balducci
authors.affiliation: Fondazione G.B. Bietti IRCCS, Rome, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Schiano-Lomoriello
authors.affiliation: Fondazione G.B. Bietti IRCCS, Rome, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Ducoli
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001699:Biometry / Q000379:methods*; D002386:Cataract / Q000000981:diagnostic imaging*; D002387:Cataract Extraction; D019781:Corneal Topography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies