Abstract
Abstract: :
Purpose: To develop a prototype based on adaptive optics to produce any desired wave-aberration in a subject's eye. The device will also measure the subject's spatial vision for each controlled aberration profile. This "aberration testing station" or "visual simulator" will be used to explore the relationship between aberrations and vision or to predict the quality of vision after refractive surgery. Methods: The apparatus is based on a closed-loop adaptive-optics device for the eye recently reported (Fernández, Iglesias & Artal, Opt. Lett., 26, 746, 2001). It uses infrared light to measure the wave-front aberration of the system plus the eye in real time with a Hartmann-Shack sensor. Defocus is added (or removed) by a computer-controlled motorized optometer, while higher order aberrations are produced by a membrane deformable mirror. An additional channel is used for vision through the device. Visual acuity, contrast sensitivity and other visual tests are performed under normal viewing for each desired aberration profile. Results: The adaptive-optics visual simulator allows for the production of the desired aberration pattern in subjects under normal viewing conditions. The range of defocus production is quite large (generated with the motorized optometer). The maximum amount of other aberration modes is approximately 0.5 microns. The actual amounts depends on the mode, being lower for the spherical-like terms. When large values of spherical aberration are desired, spherical aberration lenses are placed in front of the subject’s eye. Pure modes or any combination of modes can be produced with high repeatability and precision (usually better than 0.02 microns). The system works accurately for pupil diameters up to 6 mm in diameter (with natural pupil). The current version of the prototype still requires precise alignment of the subject's pupil with the deformable mirror, but it is robust for blinking, which renders the simulator of use for long duration visual testing. Conclusion: We built an adaptive-optics visual simulator, that produces controlled aberration patterns within the eye while the subject comfortably performs visual tasks. The simulator is a powerful, non-invasive, tool to evaluate how aberrations affect vision. Important applications are; the interactive design and testing of new ophthalmic devices and the simulation of vision previous to customized refractive surgery.
Keywords: 550 refractive surgery: optical quality • 519 physiological optics • 586 spatial vision