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A.E. Fung, P.R. Egbert, N.J. Friedman, L.A. Lott; Improved Contrast Sensitivity Obtained with Prolate Intraocular Lenses vs. Standard Spherical IOLs in Cataract Surgery . Invest. Ophthalmol. Vis. Sci. 2004;45(13):1751.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the impact of a new anterior–modified prolate intraocular lens (IOL) on post–operative contrast sensitivity as compared with traditional spherical IOLs in a clinical setting. Wavefront technology was used to develop a new lens design that seeks to reduce spherical aberrations of the pseudophakic visual system. This lens aims to balance the positive spherical aberration of the cornea, with a negative one (simulating a youthful lens), to improve vital contrast sensitivity and therefore real world visual acuity. Methods:21 patients (32 eyes) underwent temporal clear cornea phacoemulsification cataract extraction with posterior chamber IOL placement by one of two surgeons. Control eyes received a standard spherical IOL (Allergan SI 40 or Clariflex, Pharmacia 911A or 720) and study eyes received an anterior–modified prolate IOL (Pharmacia Tecnis Z9000 or Z9001). All patients had a post–operative BCVA better than 20/40 and absence of contrast–sensitivity–altering ocular pathology. Postoperative best corrected Snellen visual acuities were documented. Each pseudophakic eye was tested on a Vision Contrast Test System (VCTS) (Vistech Consultants, Inc., Dayton, OH) contrast sensitivity chart in a standardized room with a luminance of 2.2 lm/m2. Patient data were converted to a log scale contrast sensitivity value according to the Vistech Consultants table, and then nonparametric statistics were used given non–normal distribution of values. Results: AWilcoxon signed ranks test for matched pairs, revealed a statistically significant improvement in contrast sensitivity values for the anterior–modified prolate IOL over the standard spherical IOL at the most visually significant cycle per degree level, 6 (Z=–2.55, p =.011). Conclusions: Statistically significant improvements in post–operative contrast sensitivity were found using an anterior modified prolate intraocular lens over conventional spherical intraocular lens designs. Additionally, contrast sensitivity testing was again found to be an easy and useful comprehensive test of visual function that did not require literacy or verbal skills.
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