Oxygen demands with hybrid contact lenses

The purpose of this study was to assess the corneal response, as measured by corneal oxygen uptake, of keratoconic corneas to SoftPerm and SynergEyes hybrid contact lenses at the central cornea, 2.0 and 4.5 mm temporal to the central cornea, and 1 mm temporal to the limbus.

Corneal oxygen uptake rates were measured with a Clark-type polarographic electrode on the right eyes of 14 subjects and the left eye of 1 subject, all with keratoconus. Measurements were made at the central cornea, 2.0 and 4.5 mm temporal to the central cornea, and 1 mm temporal to the limbus. They were made for the open eye condition, as well as following 300 s of SoftPerm and SynergEyes hybrid contact lens wear. A one-way analysis of variance (ANOVA) was used to determine the effect of measurement location on oxygen uptake rates under uncovered eye conditions. To determine the difference among oxygen uptake rates relative to those of the uncovered eye at each measurement location for each hybrid lens, a two-way repeated measures ANOVA was used. Multiple comparisons with Tukey-Kramer adjustment were used post hoc to determine which locations were significantly different.

For the uncovered keratoconic cornea, there was no significant difference among the oxygen uptake rates associated with the three corneal locations; however, the oxygen uptake rates measured 1 mm temporal to the limbus were significantly higher than those measured at the three corneal locations. Comparison of oxygen uptake rates measured with the SoftPerm and SynergEyes lenses relative to those of the uncovered eye at each location revealed significantly higher rates at the peripheral cornea than at the central cornea. At all locations, the relative oxygen uptake rates obtained with the SynergEyes lenses were lower than those obtained with the SoftPerm lenses.

The SynergEyes lens allows significantly more oxygen to reach the cornea during wear than the SoftPerm lens at the central cornea, as well as 2.0 mm and 4.5 mm temporal to the central cornea.