Oxygen Transmissibility In Varying Extended Wear Soft Contact Lens Designs And Powers.

Background: The oxygen transmission (Dk/t) ratings of soft contact lenses are generally
based on the center of a lens with a -3.00 diopter (D) profile. This study investigated if
changes in prescription power caused a clinically significant decrease in the oxygen
transmissibility at the thickest part of the lens.
Methods: A volunteer was asked to wear several different powers of extended wear contact lenses from varying manufacturers. An anterior segment optical coherence tomographer (OCT) was used to assess the lens profile on the eye and to measure the central and/or thickest point of the lens. These values were then used to recalculate the Dk/t to compare them to the industry standards.
Results: Oxygen transmissibility is variable depending on the profile of the lens. Minus
powered lenses exhibited lower Dk/t in the peripheral aspects of the lens; the opposite
was found to be true for plus powered lenses.
Conclusions: Contact lens profiles vary based on the power of the lens, which can in turn affect the oxygen transmissibility and theoretically impact corneal health. Prescribing clinicians should be aware of the increased risks with extended wear contact lens use, especially in patients with high refractive error.