The telescopic contact lens is equipped with two functioning parts: a central pathway that gives users normal vision and an outer ring that functions like a telescope by magnifying vision 2.8x, in comparison to a pair of bird-watching binoculars that can deliver a magnification of 15x.
Light entering the outer part of the lens is reflected multiple times achieving a magnification of 2.8x. The light is then directed to the retina at the back of the eyeball.
The user is able to switch between normal and telescopic vision (you don’t want to see the world telescopically all day long!) with the help of a polarizing filter in front of the central region of the lens and a pair of liquid crystal shutters that can block one or the other of the alternate optical paths. The wearer switches the polarizing state of the shutters to alternate between regular and magnified vision.
According to New Scientist, the LCD shutter mechanism is built into a pair of Samsung 3D TV glasses modified for the purpose. However, the team believes that the LCD technology can be built into the lens, in which case it would probably have to be operated remotely.
The illustrations below give an idea of the power of the 2.8x zoom the lens is able to achieve. Being only about 1.17mm thick, it can be worn comfortably.
According to New Scientist, the lens still needs further development. The researchers said: “Although the magnified images were clearly visible in our tests, acuity fell short of the design specification.”
The team is confident that it will be possible to fix the acuity issues with improved refractive optics.
Previous lenses developed for the same purpose included a 4.4mm lens too thick to be worn comfortably. Other researchers have developed telescopic spectacles (“bioptic telescopes”) that are rather cumbersome to carry around. Another recent development was a telescopic lens that can be implanted in the eye through surgery.
The lens will help to restore sight to people with age-related macular degeneration (AMD), a condition in which the high-res fovea in the central area of the retina lose their power while the perifovea continues to function normally to deliver low-res vision. Degeneration of the fovea makes it impossible to see fine details in the field of vision. The telescopic power of the lens is designed to correct for vision impairment associated with AMD.
New scientist reports that Chris Hull, head of optometry and visual science at the City University of London, said: “Devices that help those with visual impairment are very important, particularly with the ageing population. The switchable telescopic contact lens is fascinating technology – but it will need to compete with existing low vision rehabilitation technologies in terms of clinical performance and cost.”
The contact lens being used for experimental purposes is made out of outmoded PMMA, a gas-impermeable polymer. For the market version of the lens, researchers plan to use rigid gas permeable (RGP) polymer normally used in contact lenses, and which are more comfortable to wear.
Although the telescopic contact lens is designed primarily for AMD sufferers, aspiring superheros wishing to add the advantages of “superman” telescopic vision to their growing list of gadget-enhanced powers are welcome.
News Scientist notes, however, that the ability to magnify a scene without appearing to be wearing a device could raise privacy issues similar to those raised over Google Glass.
The work was funded by DARPA, the US defense research agency.