Drs 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.
Nightly Lens Wear Needed to Retain Correction
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. Dr Adams likens this ongoing treatment to the "retainer" that orthodontic patients have to wear nightly. 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. Alternatives for presbyopia have been introduced, including fitting a contact lens for distance vision in one eye and a lens for near vision in the other eye. This is the so called monovision, now the authors show it can be achieved without the need to wear a contact lens during the day. "However, the chief problem with monovision for many people is that their stereoscopic 3D vision is degraded and many find that hard to tolerate," according to Dr Adams.
Although overnight OK is not a new technique, it has been mainly used to reduce nearsightedness (myopia) in younger patients.
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Wolters Kluwer Health