Bifocal RGP contact lenses produce better contrast visual acuity over soft lenses, study finds

Rigid gas-permeable bifocal contact lenses appear to provide presbyopic patients with better contrast visual acuity than bifocal soft contact lenses, according to a study by researchers in Japan.

Kiichi Ueda, MD, PhD, and Yasuko Inagaki, MD, PhD, compared the quality of vision of the two bifocal contact lens types in 16 healthy people with presbyopia. Each patient was randomly assigned to wear each lens for 30 minutes with a 30-minute washout period between lens application.

The researchers found that, under photopic conditions, bifocal soft contact lenses decreased distance visual acuity at the 25% contrast level and decreased near visual acuity at the 10% contrast level (P < .05). Under scotopic conditions, bifocal rigid gas-permeable contact lenses decreased distance visual acuity at the 5% contrast level (P < .05), according to the study.

Participants rated their visual clarity similarly for both lens types for distance vision, although bifocal rigid gas-permeable lenses produced clearer near vision (P < .05), the authors noted.

The study is published in the March issue of Eye & Contact Lens.