title: Comparison of intraocular lens power prediction using immersion ultrasound and optical biometry with and without formula optimization.
abstract: OBJECTIVE
  Comparison of postoperative refraction results using ultrasound biometry with closed immersion shell and optical biometry.
  
  
  METHODS
  Three hundred and sixty-four eyes of 306 patients (age: 70.6 ± 12.8 years) underwent cataract surgery where intraocular lenses calculated by SRK/T formula were implanted. In 159 cases immersion ultrasonic biometry, in 205 eyes optical biometry was used. Differences between predicted and actual postoperative refractions were calculated both prior to and after optimization with the SRK/T formula, after which we analysed the similar data in the case of Holladay, Haigis, and Hoffer-Q formulas. Mean absolute error (MAE) and the percentage rate of patients within ±0.5 and ±1.0 D difference in the predicted error were calculated with these four formulas.
  
  
  RESULTS
  MAE was 0.5-0.7 D in cases of both methods with SRK/T, Holladay, and Hoffer-Q formula, but higher with Haigis formula. With no optimization, 60-65 % of the patients were under 0.5 D error in the immersion group (except for Haigis formula). Using the optical method, this value was slightly higher (62-67 %), however, in this case, Haigis formula also did not perform so well (45 %). Refraction results significantly improved with Holladay, Hoffer-Q, and Haigis formulas in both groups. The rate of patients under 0.5 D error increased to 65 % by the immersion technique, and up to 80 % by the optical one.
  
  
  CONCLUSIONS
  According to our results, optical biometry offers only slightly better outcomes compared to those of immersion shell with no optimized formulas. However, in case of new generation formulas with both methods, the optimization of IOL-constants give significantly better results.
authors.affiliation: Department of Ophthalmology, Medical and Health Science Center, University of Debrecen, Nagyerdei blvd. 98, H-4012 Debrecen, Hungary. nemeth222@yahoo.com
authors.forename: Gabor
authors.initials: G
authors.lastname: Nemeth
authors.forename: Attila
authors.initials: A
authors.lastname: Nagy
authors.forename: Andras
authors.initials: A
authors.lastname: Berta
authors.forename: Laszlo
authors.initials: L
authors.lastname: Modis
mesh_terms: D000368:Aged; D058452:Axial Length, Eye; D001699:Biometry / Q000379:methods*; D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D055095:Optics and Photonics; D018918:Phacoemulsification; D011184:Postoperative Period; D012029:Refraction, Ocular / Q000502:physiology*; D016896:Treatment Outcome; D014463:Ultrasonography; D014792:Visual Acuity / Q000502:physiology