title: Predictability of intraocular lens power calculation formulae in infantile eyes with unilateral congenital cataract: results from the Infant Aphakia Treatment Study.
abstract: OBJECTIVE
  To compare accuracy of intraocular lens (IOL) power calculation formulae in infantile eyes with primary IOL implantation.
  
  
  METHODS
  Comparative case series.
  
  
  METHODS
  The Hoffer Q, Holladay 1, Holladay 2, Sanders-Retzlaff-Kraff (SRK) II, and Sanders-Retzlaff-Kraff theoretic (SRK/T) formulae were used to calculate predicted postoperative refraction for eyes that received primary IOL implantation in the Infant Aphakia Treatment Study. The protocol targeted postoperative hyperopia of +6.0 or +8.0 diopters (D). Eyes were excluded for invalid biometry, lack of refractive data at the specified postoperative visit, diagnosis of glaucoma or suspected glaucoma, or sulcus IOL placement. Actual refraction 1 month after surgery was converted to spherical equivalent and prediction error (predicted refraction - actual refraction) was calculated. Baseline characteristics were analyzed for effect on prediction error for each formula. The main outcome measure was absolute prediction error.
  
  
  RESULTS
  Forty-three eyes were studied; mean axial length was 18.1 ± 1.1 mm (in 23 eyes, it was <18.0 mm). Average age at surgery was 2.5 ± 1.5 months. Holladay 1 showed the lowest median absolute prediction error (1.2 D); a paired comparison of medians showed clinically similar results using the Holladay 1 and SRK/T formulae (median difference, 0.3 D). Comparison of the mean absolute prediction error showed the lowest values using the SRK/T formula (1.4 ± 1.1 D), followed by the Holladay 1 formula (1.7 ± 1.3 D). Calculations with an optimized constant showed the lowest values and no significant difference between the Holladay 1 and SRK/T formulae (median difference, 0.3 D). Eyes with globe AL of less than 18 mm had the largest mean and median prediction error and absolute prediction error, regardless of the formula used.
  
  
  CONCLUSIONS
  The Holladay 1 and SRK/T formulae gave equally good results and had the best predictive value for infant eyes.
authors.affiliation: Department of Ophthalmology, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts. Electronic address: deborah.vanderveen@childrens.harvard.edu.
authors.forename: Deborah K
authors.initials: DK
authors.lastname: Vanderveen
authors.forename: Rupal H
authors.initials: RH
authors.lastname: Trivedi
authors.forename: Azhar
authors.initials: A
authors.lastname: Nizam
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Lynn
authors.forename: Scott R
authors.initials: SR
authors.lastname: Lambert
mesh_terms: D001036:Aphakia, Postcataract / Q000503:physiopathology / Q000601:surgery*; D001699:Biometry; D002386:Cataract / Q000151:congenital* / Q000503:physiopathology; D002387:Cataract Extraction; D006801:Humans; D007223:Infant; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D055095:Optics and Photonics; D012029:Refraction, Ocular / Q000502:physiology; D015203:Reproducibility of Results; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology