Eyeball squeezing could correct sight

A light tap on the side of your head could one day restore your eyesight,
believe scientists. The tap would tighten a band of artificial muscle wrapped
round your eyeballs, changing their shape and bringing blurry images into
focus. While the idea has a high ‘yuk’ factor, the people behind it are
confident it will be a safe and effective way to improve vision.

Exclusive from New Scientist

Mohsen Shahinpoor and his team at the
University of New Mexico call their artificial
muscle a "smart eye band". It will be stitched to
the sclera, the tough white outer part of the
eyeball, and activated by an electromagnet in a
hearing-aid-sized unit fitted behind one ear.

Most of the eye’s focusing is done by the cornea, the hard transparent
surface that covers both the pupil and the iris; the lens is responsible only
for fine-tuning. Light travels through the cornea and lens to focus on the
retina at the back of the eyeball. The closer an object is, the farther back in
the eye it will be focused. The lens compensates by adjusting its strength to
bring the focus back onto the retina.

If the cornea or lens do not focus strongly enough or the eyeball is too short,
the light will focus behind the retina, blurring images of close-up objects.
This is long-sightedness. Conversely, if the eyeball is too long, the light will
focus in front of the retina, yielding the blurry images of far-off objects
characteristic of short-sightedness.

Elongated eyeball

Tightening the smart eye band causes the eyeball to elongate, just as
squeezing the middle of a peeled hard-boiled egg causes the egg to
lengthen. In long-sighted people this pushes the retina backwards, bringing
close-up objects back into focus.

Expanding the eye band causes the eyeball to shorten. In short-sighted
people this will bring the retina forward to intersect with the focused light,
making far-off images sharp and clear again.

Stitching a band of artificial muscle to your eyeball sounds drastic, but
Shahinpoor says the necessary surgical techniques are already commonly
used for treating detached retinas. He claims his smart eye band is far more
flexible than laser surgery, in which a laser flattens the cornea by eroding
part of it. Laser surgery can only correct short-sightedness.

Click and read

With the smart eye band implanted, you’d set your eyes to read a book, say,
by clicking a button on the device sitting behind your ear. This would
generate a magnetic field to activate the eye band’s artificial muscle.

The artificial muscle comprises a series of "bi-strips" (see graphic), each
made up of two lengths of a biocompatible polymer containing lithium ions,
surrounded by a coil of thin gold wire. At the end of each bi-strip is an
electrode.

Switching on the magnetic field induces a pulse of current in the coil, which
in turn builds up a small charge on the electrodes. The positively charged
lithium ions in the polymer are attracted to the negative electrode, causing
the whole bi-strip to bunch up and tighten the band around the eyeball. So
the eye’s focal length becomes electronically controllable.

Though Shahinpoor’s idea is still on the drawing board, Jim Schwiegerling of
the Optical Sciences Center at the University of Arizona says the technology
could be of enormous benefit to older people who have lost the ability to
change focus from distant to near objects.

"When you sit down to read a book, you could just switch it on, and when
you are done reading, you could turn it off and go out and drive a car," he
says. Shahinpoor will present the design for his bionic eye at an optical
technology conference in San Diego, California later in March.

http://www.newscientist.com/news/news.jsp?id=ns99992064