Purpose: The aim of the study was to evaluate the performance of a new monthly silicone hydrogel lens for daily, flexible, and extended (up to six nights) wear. The study measures included biomicroscopy and subjective symptoms, such as comfort upon insertion and at the end of the day.

Methods: Nine fitters in Germany refitted 230 wearers of four monthly lenses (with at least three months experience with the respective lens) in a new silicone hydrogel, which was not marketed at the time of the study. At visit one, fitters took baseline values for fit, biomicroscopy and subjective symptoms with the habitual lenses. They were then fitted with the new lens and a first evaluation was done, prior to dispense. Additional visits took place two weeks and one month after dispense. Wearers and fitters answered the same and additional questions like those for the habitual lens at the first visit. Among those were questions about the frequency of problems, like feeling of dry eyes, and the severity of the problem. Wearers indicated which lens they preferred and why, or if the two were performing equally well. At the final visit, patients were asked also to choose between the habitual and the test lens.

Results: Of the 217 wearers that completed the study, the majority preferred the test lens, especially for end of day comfort. This was statistically significant. Wearers also liked the possibility of being able to sleep in the lens, at least occasionally. About 70% indicated that they did fall asleep once in a while with their habitual lenses and about 15% said they slept with the lenses (one of which was also a silicone hydrogel). The average wearing hours increased by about an hour for all wearers, and more did sleep with their lenses than before. They intended to do this only one or two nights per week, on average. The preference was very high (more than 80%) in the former Proclear group. This can be attributed to the fact that this lens is often used for problem patients, who seem to benefit the most from the increased oxygen permeability and lesser dehydration of the lower water content silicone hydrogel lens.

Conclusion: The new monthly silicone hydrogel is mainly worn on a daily wear basis. Its increased oxygen permeability allows wearers to fall asleep or even occasionally sleep with the lenses if they want to. The lens provided an increase of the end of day comfort and the average wearing time increased by one hour.