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Near Vision Restored By Wearing Contact Lens Overnight

Wearing contact lenses overnight may offer a non-surgical alternative to restoring near vision without the need for glasses, according to a new Australian study that successfully tested the method in middle-aged patients with presbyopia, or age-related loss of near vision.

Paul Gifford and Helen A Swarbrick of the School of Optometry and Vision Science at the University of New South Wales in Sydney write about their findings in the April issue of Optometry and Vision Science, the official journal of the American Academy of Optometry.

By middle age, most people experience age-related loss of near vision or presbyopia. This is because as we age, the lens of the eye loses elasticity making it more difficult for it to change shape from its normal resting position in order to focus on near objects.

This is why, even if you had excellent vision before, you find yourself by middle age holding packets of food at arm's length in supermarkets as you try to read the tiny print on the nutrition label.

To correct this, many people find themselves needing reading glasses, or having to change to bifocals.

But an emerging technique called hyperopic orthokeratology (OK) may offer an alternative where during the day you don't need to wear any eye correction because wearing a specially designed rigid contact lens overnight corrects the loss of near vision sufficiently to last during the day.

The OK contact lens flattens the cornea, the transparent tissue at the front of the eye, just enough to compensate for the loss of lens stiffness so near-vision focus is possible.

For their study, Gifford and Swarbrick tested the method in 16 middle-aged patients with presbyopia who were aged between 43 and 59 years.

The patients wore a custom-made OK lens in one eye overnight for a week. The other eye was left untreated.

The results showed that in all patients the OK lens restored near vision in the treated eye.

In fact, near vision improved after only one night of wearing the lens, and increased further as the week went by.

When they examined the patients' treated eyes, the researchers confirmed that the OK lenses had altered the shape of the cornea, as intended.

And when the patients stopped wearing the OK lens, their corneas returned to their previous shape within a week or so.

Vision in the untreated eye was unaltered, and all patients retained normal distance vision in that eye.

Current contact lens treatments to correct presbyopia include fitting a contact lens for distance vision in one eye and one for near vision in the other. This is called "monovision".

Although overnight lens wearing is not new, until now most applications have been to help younger patients with short sight (myopia).

But with this study, Gifford and Swarbrick have shown this can be achieved without the need to wear a contact lens during the day to correct near-vision loss.

In a press statement, Anthony Adams, editor of Optometry and Vision Science, says the OK technique is like the "retainer" that orthodontic patients wear every night to correct their teeth.

He says Gifford and Swarbrick have shown that the OK method is "quite viable as a nonsurgical option for monovision that does not require wearing contact lenses during the day, although it does require 'retainer' orthokeratology contact lenses to be worn overnight."

He suggests this option will appeal to many, especially as the cornea is not permanently altered; the changes to the treated eye are fully reversible.

The study was supported by a grant from the Australian Research Council Linkage Project, with industry partners Bausch & Lomb Boston, Capricornia Contact Lens Pty Ltd., and BE Enterprises Pty Ltd.

In another recent study, researchers from King's College London identified 24 new genes that are responsible for causing short-sightedness (myopia).

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