People suffering from congenital eye diseases and individuals who have injured their eyes in accidents could improve their vision with a smart contact lens containing an artificial iris. The smart contact lens has been developed by Herbert De Smet and his team at the University of Ghent and was recently described at an International Electron Devices Meeting held in San Francisco.
Injuries, congenital deformities, and eye diseases can prevent the expansion and contraction of the iris. In such cases, vision is impaired. In bright sunlight, the inability of the iris to contract results in the patient experiencing pain.
The solution in such cases is to wear dark glasses or a dark contact lens. However, patients often complain that dark contact lenses or sunglasses are not always sufficiently dark in bright conditions. They often still experience pain. The smart contact lens can also darken, mimicking contraction of the pupil. In bright light conditions the patient will be able to see better and avoid pain; however, the smart contact lens also allows the wearer to also see properly in low light conditions.
The lens contains a series of concentric LCDs which mimic the natural expansion and contraction of the pupil; processes that are controlled by the iris. The lens contains three concentric rings of LCDs surrounding a clear central area. In low light conditions, the LCDs are inactive and allow the maximum light to pass through. In brighter conditions the LCDs are activated to prevent light passing through, mimicking the contraction of the pupil. Surrounding the LCDs are ten organic solar cells to provide power and electronics that link the solar cells to the drivers of the LCDs.
De Smet and his team believe the smart contact lens could benefit some 200,000 patients that have problems with their irises because of cancer, disease, or injury.
De Smet, who is a professor who works on intelligent sensors, has succeeded in putting a range of electronic components into lenses and is currently working on the incorporation of antennas, batteries, chemical sensors and control electronics. De Smet’s team has already incorporated a liquid crystal display into a contact lens.
Researcher Florian De Roose from Imec in Leuven, Belgium collaborated with De Smet and worked on adding flexible control electronics to the lenses. De Roose developed low-power driver electronics to control the LCDs. The electronics take up approximately 0.75 sq. mm and consist of thin transistors which are placed on a thin and flexible transparent film. The film is made from a flexible polymer and the control chip, which is about 50% transparent, is placed right on the edge of the lens so it does not interfere with the wearer’s vision. The solar cells are capable of supplying sufficient power for the 25-microwatt system.
De Roose explained that the photovoltaics used to power the LCDs also act as light sensors. He also said the more light there is, the more power is generated, which will ensure the artificial iris has sufficient power to contract. He pointed out that photovoltaics can be made in colors that look natural, although the team has yet to work on aesthetics.
One of the problems faced by the team was how to ensure the lenses were sufficiently flexible. While the lenses can stretch, the components used in the smart contact lens cannot and are merely flexible. Developing components that can also stretch is the goal, although a get around is to be very careful about the architecture of the lens. The team must also ensure the lenses are safe to use and do not interfere with oxygen and water transfer through the lens to the cornea.
While the parts have been shown to work, the team now must put all of those components together into a working smart contact lens.