title: A 3-D "Super Surface" Combining Modern Intraocular Lens Formulas to Generate a "Super Formula" and Maximize Accuracy.
abstract: OBJECTIVE
  Cataract surgery is the most common eye surgery. Calculating the most accurate power of the intraocular lens (IOL) is a critical factor in optimizing patient outcomes.
  
  
  OBJECTIVE
  To develop a graphical method for displaying IOL calculation formulas in 3 dimensions, and to describe a method that uses the most accurate and current information on IOL formulas, adjustments, and lens design to create one "super surface" and develop an IOL "super formula."
  
  
  METHODS
  A numerical computing environment was used to create 3-D surfaces of IOL formulas: Hoffer Q, Holladay I, Holladay I with Koch adjustment, Haigis, and SRK/T. The surfaces were then analyzed to determine where the IOL powers calculated by each formula differed by more than 0.5, 1.0, and 1.5 diopters (D) from each of the other formulas. Next, based on the current literature and empirical knowledge, a super surface was rendered that incorporated the ideal portions from 4 of the 5 formulas to generate a super formula. Last, IOL power values of a set of 100 eyes from consecutive patients at an eye institute were calculated using the 5 formulas and super formula. The study was performed from December 11, 2014, to April 20, 2015. Analysis was conducted from February 18 to May 6, 2015.
  
  
  METHODS
  Intraocular lens power value in diopters and the magnitude of disparity between an existing individual IOL formula and our super formula.
  
  
  RESULTS
  In the 100 eyes tested, the super formula localized to the correct portion of the super surface 100% of the time and thus chose the most appropriate IOL power value. The individual formulas deviated from the optimal super formula IOL power values by more than 0.5 D 30% of the time in Hoffer Q, 16% in Holladay I, 22% in Holladay I with Koch adjustment, 48% in Haigis, and 24% in SRK/T.
  
  
  CONCLUSIONS
  A novel method was developed to represent IOL formulas in 3 dimensions. An IOL super formula was formulated that incorporates the ideal segments from each of the existing formulas and uses the ideal IOL formula for an individual eye. The expectation is that this method will broaden the conceptual understanding of IOL calculations, improve clinical outcomes for patients, and stimulate further progress in IOL formula research.
authors.affiliation: Wilmer Eye Institute, Johns Hopkins Medical Institutions, Baltimore, Maryland.
authors.forename: John G
authors.initials: JG
authors.lastname: Ladas
authors.affiliation: Wilmer Eye Institute, Johns Hopkins Medical Institutions, Baltimore, Maryland.
authors.forename: Aazim A
authors.initials: AA
authors.lastname: Siddiqui
authors.affiliation: Jules Stein Eye Institute, University of California, Los Angeles, School of Medicine.
authors.forename: Uday
authors.initials: U
authors.lastname: Devgan
authors.affiliation: Wilmer Eye Institute, Johns Hopkins Medical Institutions, Baltimore, Maryland.
authors.forename: Albert S
authors.initials: AS
authors.lastname: Jun
mesh_terms: D000465:Algorithms; D058452:Axial Length, Eye / Q000473:pathology; D001699:Biometry; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007910:Lenses, Intraocular; D055095:Optics and Photonics