Presbyopia is an age-related loss of accommodation of the human eye that manifests itself as inability to shift focus from distant to near objects. More than 90% of the people over 45 need correction of presbyopia. The conventional corrective lenses (bifocal, trifocal) have been around for more than 200 years and have some drawbacks. They have a limited field of view for each vision task, requiring user to gaze down to accomplish near vision and in some cases causing dizziness and discomfort. Some users need three different eyeglasses for reading, computer, and driving. Progressive lenses cause some distortion. Recently we have demonstrated switchable diffractive liquid crystal (LC) lens with binary ON and OFF states. In the proposed project, our goal is to develop a tunable, low-cost electro-optic lens with continuous focusing powers and high optical performance for near-, intermediate-, and distance vision. The whole aperture with the same power is used for each vision task. Such a device may have revolutionary impact on the field of vision care. Existing LC lenses have an aperture of 10-15 mm, and the power can only be switched between plano and 1 diopter (D) (or 2D). The driver box is 4W4W2 cm3, which is bulky. They are not suitable for practical ophthalmic applications. In this study, we will develop a novel, high performance, cost-effective varifocal LC lens with a compact electronic driver and controller. The focusing power of the lens can be continuously tuned from plano to +4D by applied voltages. This range covers the typical add powers needed for presbyopes, and it allows almost all patients to use the same lens. We will fabricate lenses with an aperture around 40mm, which satisfies the requirement for practical applications. The light efficiency will be close to 100%. These three specifications have not been met before. We will design a novel closed-loop driver circuit with good reliability and high power efficiency. In addition, we will develop a minicontroller that allows change of the focus power by simply pressing a button, which is practical and reliable;in the second phase of this project, we will develop a prototype of the eyeglass that allows autofocus function. The size of the driver will be only 5W5W2 mm3. Clinical studies will be performed to assess how the wearers function and perceive the new spectacles. This kind of lens is promising to become an alternative of conventional area division multi-focal spectacle lenses used by presbyopes. They may have the potential of revolutionizing the field of presbyopia correction. The new eyeglass will significantly improve the quality of life for a large population. Applications can be extended to fields where varifocal lens elements with low operation voltages, relatively large diameters and fast response time are desirable. For example, a single lens of this kind can be used as a new phoropter to measure the refractive errors and visual acuity and for rapid depth scanning in three-dimensional biomedical imaging. Correction of low vision with high quality optics in the periphery will also have high impact. This would be our next focus of research.
The proposed electro-optic adaptive eyeglass allows correction of near-, intermediate-, and distance vision. The lens has high diffraction efficiency, larger aperture, large tunable range, high optical quality, good response time, and low driving voltages. The focusing power can be continuously tuned by the applied voltages. The cost can be comparable or lower than progressive lenses. This kind of lens is promising to replace conventional area-division multi-focal spectacle lenses used by presbyopes. They have the potential of revolutionizing the field of presbyopia correction. Needlessly to say, the new eyeglass will significantly improve the quality of life for a large portion of the population. Applications can be extended to fields where varifocal lens elements with low operation voltages, relatively large diameters and fast response time are desirable. For example, a single lens of this kind can be used as a new phoropter to measure the refractive errors and visual acuity. The current phoropters are bulky and require the ophthalmologist/technician to manually adjust the add lenses, which is also time consuming. The new phoropter is compact, light weight, and easy to use. Correction of low vision with high quality optics in the periphery will also have high impact. This would be our next focus of research.
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