Washington: Scientists claim to have developed new contact lenses that can restore age-related loss of near vision when worn by the user every night. Most people have age-related declines in near vision (presbyopia) requiring bifocals or reading glasses. The emerging technique called hyperopic orthokeratology (OK) may provide a new alternative for restoring near vision without the need for glasses, according to a study.
For middle-aged patients with presbyopia, wearing OK contact lenses overnight can restore up-close vision in one eye, according to the study by Paul Gifford and Helen A Swarbrick from the University of New South Wales, Sydney. The study included 16 middle-aged patients (43 to 59 years) with age-related loss of near vision, or presbyopia. Orthokeratology is a clinical technique to correct vision using specially designed rigid contact lenses to manipulate the shape of the cornea.
Gifford and Swarbick 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.
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 dequivalent 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. By about age 45 to 50, most people need bifocals or some other form of vision correction to restore vision for reading and other up-close tasks, according to the study published in the journal Optometry and Vision Science. 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," researchers said.