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Closing In on Help for Near Vision

April 3, 2013
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Attention, Boomers: An emerging technique called hyperopic orthokeratology (OK) may provide a new alternative for restoring near vision without the need for glasses, according to a study appearing in this month’s Optometry and Vision Science of the American Academy of Optometry. 

For middle-aged patients with presbyopia — an affliction that causes difficulty in seeing close objects clearly — wearing contact lenses overnight can restore up-close vision in one eye, according to the study by Paul Gifford and Helen A Swarbrick, of the University of New South Wales, Sydney. 

“The authors have shown the feasibility of correcting one eye for near vision through OK, in which overnight contact lens wear shapes the cornea of one eye to allow in-focus near vision for reading,” comments Anthony Adams, editor-in-chief of Optometry and Vision Science.

The study included 16 middle-aged patients (43 to 59 years) with age-related loss of near vision, or presbyopia. Presbyopia is caused by age-related loss of flexibility in the cornea — the transparent front part that lets light into the eye.

Orthokeratology is a clinical technique to correct vision using specially designed rigid contact lenses to manipulate the shape of the cornea. Adams likens OK therapy to orthodontic treatment using braces to change the alignment of the teeth.

Gifford and Swarbrick evaluated a “monocular” technique, with patients wearing a custom-made OK lens in one eye over­night for one week. To preserve normal distance vision, the other eye was left untreated.

In all patients, the monocular OK technique was successful in restoring near vision in the treated eye. The improvement was apparent on the first day after overnight OK lens wear, and increased further during the treatment week. 

An eye examination confirmed that the OK lenses altered the shape of the cornea, as they were designed to do.

Vision in the untreated eye was unaffected, and all patients retained normal distance vision with that eye; essentially this gives the patient the equivalent of monovision that is usually done with contact lenses or surgery.

To retain the correction in near vision, patients had to continue wearing their OK lenses every night. 

 As expected, when patients stopped wearing their OK lens after the treatment week, presbyopia rapidly returned.

Although overnight OK is not a new technique, it has been mainly used to reduce nearsight­edness (myopia) in young­er patients. 

The new study suggests that overnight OK lenses are a feasible alternative for correction of presbyopia, “sufficient to provide functional near vision correction white retaining good distance visual acuity,” Gifford and Swarbrick write. 

The technique is safe, with the cornea returning to its previous shape about a week after the patient stops wearing the lenses.

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