Clinical performance of microchannel contact lenses.

PURPOSE

It has been suggested that microchannels placed on the posterior surface of hydrogel contact lenses increase transverse lens movement and therefore increase tear mixing. Lens designs, which can improve tear exchange without adversely affecting lens performance, may play a significant role in improving the safety of contact lens wear. Our aim was to investigate the effect of posterior lens surface microchannels on contact lens performance.

METHODS

A randomized, single masked pilot study was conducted. Fifteen experienced hydrogel lens wearers were randomly assigned to wear a microchannel lens (MC) in one eye and a standard hydrogel lens design (STD) in the fellow eye over a period of 6 hours. A range of objective and subjective clinical performance measures were assessed, including visual acuity, lens movement, comfort and patient preference.

RESULTS

There were no significant differences between the MC and STD lenses with respect to vision measures, corneal staining, and bulbar and limbal redness (p > 0.05). The MC lenses produced significantly less conjunctival staining than the STD lenses and showed greater lens movement in primary gaze (p < 0.05). Lens distortion with blinking was evaluated through topographic assessment of the contact lenses on eye, and no significant differences were observed in central distortion levels between the two lens designs (p > 0.05). Subjective evaluation of the lenses with respect to comfort, vision, and overall satisfaction did not vary significantly between the two lens types (p > 0.05).

CONCLUSIONS

The results of this study suggest that posterior lens surface microchannels do not adversely affect contact lens performance or subjective lens preference over a short-term wearing period. The MC lenses appear to produce less physiological impact on the conjunctival surface than STD lenses with less conjunctival staining observed with the MC lenses. Clinical investigation of the performance of this type of lens design in a larger group of subjects, over longer wearing periods, is warranted.