Aberration Analyses Needed for FDA Evaluation of Safety and Effectiveness of Wavefront-guided Refractive Surgical Devices

Abstract

Manufacturers of refractive surgical lasers are seeking Food and Drug Administration (FDA) approval for refractive surgery based on wavefront measurements rather than manifest refractions. This article draws attention to the need for better understanding of the relationship between aberrations and visual function and better testing methods for evaluating safety and effectiveness of wavefront-guided refractive surgery. Before U.S. market approval for a new medical device, the FDA must determine whether the manufacturer has provided reasonable assurance that the device is safe and effective for its intended use, based on valid scientific evidence. The issues discussed here are based on FDA reviewers' experiences in evaluating Investigational Device Exemption (IDE) and Premarket Approval (PMA) applications for wavefront-guided refractive lasers. Even an optimal wavefront correction can provide only a marginally greater visual function benefit than a conventional spherocylindrical correction in a normal eye. Actual benefits are even smaller or nonexistent because variability from uncontrollable sources (eg, healing, aging, accommodation, pupil size, or ocular biomechanical effects) are typically larger than the errors treated. The effects of higher order aberrations and aberration changes on visual function are complex and poorly understood. The FDA's need for better tools to assess safety and effectiveness of wavefront-guided refractive surgery has stimulated major research efforts within the vision, ophthalmic, and optometric research communities. More research is needed to better understand the relationship between aberrations and visual function, and to be able to predict the visual effects of specific aberration changes in individual eyes. This research would have been more appropriately done before rather than after clinical trials for wavefront-guided refractive lasers.