A Telescope for the Eye

In age-related macular degeneration (AMD) – the leading cause of blindness in the elderly, there is loss of central vision due to damage to the eye’s retina.  Visual aids that magnify incoming light help AMD patients see by spreading light around to undamaged parts of the retina. While these optical magnifiers can assist patients with a variety of important everyday tasks such as reading, identification of faces, and self-care, these devices have not gained widespread acceptance because they either use bulky spectacle-mounted telescopes that interfere with social interactions, or micro-telescopes that require surgery to implant into the patient's eye.  Joseph Ford, from the University of California/San Diego (UCSD, California, USA), and colleagues have developed a slim, telescopic contact lens that can switch between normal and magnified vision. The new lens system uses tightly fitting mirror surfaces to make a telescope that has been integrated into a contact lens just over a millimeter thick. The lens has a dual modality: the center of the lens provides unmagnified vision, while the ring-shaped telescope located at the periphery of the regular contact lens magnifies the view 2.8 times. To switch back and forth between the magnified view and normal vision, users would wear a pair of liquid crystal glasses originally made for viewing 3-D televisions. These glasses selectively block either the magnifying portion of the contact lens or its unmagnified center. The liquid crystals in the glasses electrically change the orientation of polarized light, allowing light with one orientation or the other to pass through the glasses to the contact lens.  The team tested their design both with computer modeling and by fabricating the lens. They also created a life-sized model eye that they used to capture images through their contact lens-eyeglasses system. Tests showed that the magnified image quality through the contact lens was clear and provided a much larger field of view than other magnification approaches, but refinements are necessary before this proof-of-concept system could be used by consumers.