We evaluated experimentally the optical quality of poly(methyl methacrylate) (PMMA) (Storz 68UV, AMO PC58) and silicone (AMO SI19, Adatomed 90D) intraocular lenses (IOLs) and compared the results with our clinical data. We measured surface and image quality using the Zygo laser interferometer and modulation transfer function (MTF) using the Ealing EROS MTF analyzer. Contrast acuity was tested clinically with glare and without glare (Regan charts); AMO PC58, n = 18; AMO SI19, n = 7; Adatomed 90D, n = 18). Modulation transfer function and image quality were slightly better with PMMA IOLs but the reduction of MTF with silicone lenses was within the 1/8 diopter defocus range. Surface quality of silicone IOLs was superior to that of PMMA IOLs. Contrast acuity measured clinically was also slightly better with PMMA IOLs at low contrast and with glare but differences were not significant. Our results suggest that optical and visual quality of silicone IOLs is slightly lower than with PMMA IOLs. Experimental and clinical results correlated closely. However, the small differences observed are unlikely to be significant clinically.

The STORZ TRUE VISTA bifocal intraocular lens was evaluated in a laboratory setting and during clinical trials. The Modulation Transfer Function and Through Focus Response were measured in a simulated eye chamber for selection of optimal add zone size, location, power and pupil dependency. Results indicate the optimaldesign to be an annular add power of+4D having a 1 .5 millimeterinner diameter and a 2.6 millimeter outer diameter. Optical performance was predicted using computer ray trace and Fourier analysis. Laboratory testing confirmed design performance achieved through the manufacturing process. Clinical results correlate well with Through Focus Response but less well with Modulation Transfer Function. 0-8194-11

The study of insertion and deployment of foldable IOL's in cadaver eyes is enhanced by viewing the process from the posterior pole position. A video system was constructed to view IOL placement in sectioned eyes from the posterior position. All tissue used in this study were prepared using the VISUALEYES Surgical Practice System (Visitec Co., Sarasota, FL). This system allows for the precise placement and resection of the proximal third of the posterior segment of the globe. The remaining two-thirds of the globe is then placed onto the eye holder, which allows the tissue to be viewed from the posterior position. After the tissue has been prepared and attached to the fixation plate, the entire assembly is attached to the video system. A variety of intraocular procedures can then be performed utilizing this system. Both anterior and posterior views can be video taped for later analysis. Parameters such as IOL diameter, haptic length, positioning of the IOL within the eye and unfolding characteristics can be assessed using this system. This paper discusses the development of this device and presents examples of its use in the study of foldable IOL deployment.

The HYDROVIEW® intraocular lens is a biconvex foldable hydrogel lens configured as a conventional one-piece design. The unfolding time is approximately constant with lens dioptric power at an average of2.4 seconds, and increases with the length oftime the lens is held in air prior to implantation. Mechanical recovery can be modeled as a non-linear critically damped harmonic oscillator, which demonstrates the controlled manner ofunfolding. The Modulation Transfer Function at 30 cycles/degree reaches an average of 95% of its pre.-fold value within one hour after being released from folding and recovers completely to its pre-fold values within 24 hours. Interferometrically measured root-mean-square transmitted wavefront error and Strehl Ratio both recover to pre-fold values within 24 hours after folding. Dehydration for a period of 10 minutes followed by folding, then rehydration and unfolding was found to have no significant effect on lens power (<0. 15 Diopter) or resolution. Neither temperatures in excess of 120°C, which may be used during sterilization, nor temperatures as low as -85°C were found to have any significant effect on lens power and resolution.