title: Evaluation of an unused 1952 Ridley intraocular lens.
abstract: OBJECTIVE
  To evaluate an unused 1952 historic Ridley intraocular lens (IOL) brought to Bombay, India, in 1952 from an Oxford Ophthalmologic Conference in England and given to 1 of the authors during his residency.
  
  
  METHODS
  Alcon Laboratories, Fort Worth, Texas, USA.
  
  
  METHODS
  The Ridley IOL was evaluated at Alcon Laboratories, Inc., using the established procedures of its Intraocular R&D Laboratories. Various optical and physical aspects of the Ridley lens were evaluated including (1) dimensions, (2) weight, (3) power, (4) resolution efficiency and modulation transfer function (MTF), (5) surface sphericity by interferometry, (6) ultraviolet (UV)-visible transmission characteristic, (7) attenuated total reflectance (ATR)-Fourier transform infrared reflectance spectrum, and (8) cosmetics by visual inspection using light microscopy.
  
  
  RESULTS
  This 8.5 mm diameter, 2.4 mm thick, 23 diopter biconvex IOL weighed 108 mg. The ATR spectrum, UV-visible transmission, and refractive index confirmed its poly-(methyl methacrylate) material. The 0.56 MTF value at 100 line pairs/mm, per the International Standards Organization--IOL Optics Standard, and 93% resolution efficiency in water, per the American National Standard Institute IOL Optics Standard, revealed the IOL's excellent optics. This was confirmed by 0.278 wave root mean square surface figure as measured by Zygo interferometer using a 633 nm wavelength. Visual inspection revealed rough edges with sharp corners and some surface scratches. Early clinical experience with Ridley IOLs in Bombay, India, is briefly given.
  
  
  CONCLUSIONS
  The Ridley IOL had excellent optical quality, meeting the requirements of current IOL optics standards. The selection of its dimensions was guided by the human crystalline lens, and the Ridley IOL was half as bulky. Although its clinical results were mixed, successful cases inspired subsequent improvements, leading to modern, highly satisfactory IOLs. This IOL represented a revolutionary innovation in ophthalmology.
authors.affiliation: Alcon Laboratories, Fort Worth, Texas 76134-2099, USA.
authors.forename: A S
authors.initials: AS
authors.lastname: Patel
authors.forename: D R
authors.initials: DR
authors.lastname: Carson
authors.forename: P H
authors.initials: PH
authors.lastname: Patel
mesh_terms: D004739:England; D049673:History, 20th Century; D007910:Lenses, Intraocular / Q000266:history / Q000592:standards; D008857:Microscopy, Interference; D055095:Optics and Photonics / Q000266:history; D019904:Polymethyl Methacrylate / Q000032:analysis / Q000266:history / Q000592:standards; D011474:Prosthesis Design / Q000266:history; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D019904:Polymethyl Methacrylate