Washington: 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.
"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, OD, PhD, 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. Dr Adams likens OK therapy to orthodontic treatment using braces to change the alignment of the teeth.
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.
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.
The technique is safe, with the cornea returning to its previous shape about a week after the patient stops wearing the lenses.
The study was recently published in Optometry and Vision Science.