A truly fish-eyed lens

The first presbyopia patients may, in as little as five years, see the world through an autofocus contact lens that needs nothing but the sun to offer perfect vision.

The three technology and healthcare giants already in the R&D race for autofocus lenses has not put off the University of Wisconsin, Madison team led by engineer, Professor Hongrui Jiang.

The engineers have mapped out their future contact lens, and are prototyping the electronics and mechanisms that will one day be embedded within it.

Professor Jiang’s team has two possible approaches for adjusting the focus of the contact lens. The first is inspired by the compound eyes of insects.

It comprises thousands of individual microlenses that each point in a different direction to capture a different part of the world ahead, which would give a larger field of view.

The second utilises a silicone oil drop and separate water drop. These substances will not mix, but can be squeezed into different focal lengths by electric fields, Professor Jiang told OT.

Insects are not the only creatures from the animal kingdom that the group has borrowed visual tricks from – the special retina of the elephant nose fish was another.

The fish, which lives in very low light conditions, has evolved special, microscopic cup-like structures with reflective walls to intensify the light the eye receives.

Professor Jiang said the researchers are hoping to incorporate this fishy trick into the design for the sensors of the contact lenses.

He added: “The sensors must be extremely small and capable of acquiring images under low-light conditions, so they need to be exquisitely sensitive to light.”

The team also has twin ideas for the sensors to detect at what distance the eye is looking. Professor Jiang explained: “One is to have an infrared sensor to detect the distance to the object of interest. Another way is to have an imager on the contact lens, which takes an image and analyses the sharpness of the image to determine how much the lens is out of focus. Either way, the brain still needs to take an active role to fine-tune the eye.”

The plan is for the electronics in the future contact lens to be powered by sunlight, he said.

“It’s a challenge we have been working on. We showed it’s possible to have a single device to harvest energy from light and store the electrical energy. But the storage is not high enough yet,” he noted.

Professor Jiang estimated a prototype suitable for use in a clinical trial was between five and 10 years away. When ready, the self-adjusting contact lenses would not cost much more than conventional lenses, he said.

“There’s a huge market for this and, with mass production, the cost is not likely to be a barrier,” he concluded.