Evaluation of an unused 1952 Ridley intraocular lens

Purpose: 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. Setting: Alcon Laboratories, Fort Worth, Texas, USA. Methods: The Ridley IOL was evaluated at Alcon Laboratories, Inc., using th e established procedures of its Intraocular R&D Laboratories. Various optic al and physical aspects of the Ridley lens were evaluated including (1) dim ensions, (2) weight, (3) power, (4) resolution efficiency and modulation tr ansfer function (MTF), (5) surface sphericity by interferometry, (6) ultrav iolet (UV)-visible transmission characteristic, (7) attenuated total reflec tance (ATR)-Fourier transform infrared reflectance spectrum, and (8) cosmet ics by visual inspection using light microscopy. Results: This 8.5 mm diameter, 2.4 mm thick, 23 diopter biconvex IOL weighe d 108 mg. The ATR spectrum, UV-visible transmission, and refractive index c onfirmed its poly-(methyl methacrylate) material. The 0.56 MTF value at 100 line pairs/mm, per the International Standards Organization-IOL Optics Sta ndard, and 93% resolution efficiency in water, per the American National St andard Institute IOL Optics Standard, revealed the IOL's excellent optics. This was confirmed by 0.278 wave root mean square surface figure as measure d by Zygo interferometer using a 633 nm wavelength. Visual inspection revea led rough edges with sharp corners and some surface scratches. Early clinic al experience with Ridley IOLs in Bombay, India, is briefly given. Conclusion: The Ridley IOL had excellent optical quality, meeting the requi rements of current IOL optics standards. The selection of its dimensions wa s guided by the human crystalline lens, and the Ridley IOL was half as bulk y. Although its clinical results were mixed, successful cases inspired subs equent improvements, leading to modern, highly satisfactory IOLs. This IOL represented a revolutionary innovation in ophthalmology. (C) 1999 ASCRS and ESCRS.