Clinical Evaluation of a Topographically Based Contact Lens Fitting Software

Abstract

Background. Second generation corneal topography-based contact lens software programs attempt to fit the cornea based on topographical information rather than simulated keratometry and nomogram-based fits. The EyeSys System 2000 Pro-Fit software (Version 3.1) was clinically evaluated for efficiency in fitting rigid gas permeable (RGP) lenses on 22 normal subjects. Methods. Balanced manifest refractions, slitlamp examinations, keratometry, computerized topographic analysis and lens fitting, and manual diagnostic RGP fitting were performed on all patients. The topographically fit eyes were compared to corresponding eyes which were manually fit with diagnostic trial lenses. Lens parameters for the topographically fit eye were chosen after an optimal fluorescein pattern was achieved by either accepting the initially recommended Pro-Fit lens or a modification. Final lens parameters were based on clinical performance. Lenses were reordered when there was a need for base curve changes of 0.1 mm or more, power alterations of ±0.50 D or more, or for any alteration in diameter, optic zone, or edge lift. Results. Both manual and topographically fit groups achieved 17/22 (77%) eyes successfully fit without any subsequent lens modifications. Time records for the manually fit group averaged 16.5 min, whereas the topographically fit group averaged 8.0 min. Conclusions. This study reports a 51.4% reduction in chair time when using a topographically based contact lens software program while achieving the same clinical results as in traditional diagnostic RGP fitting, suggesting increased efficiency in fitting RGPs to normal eyes.