Abstract: Plugs and contacts

Wow - this is surprising. They put plugs in some contact lens patients and pretended to put plugs in others - and the faked ones were the only ones to show any difference in their tear film.

Eye Contact Lens. 2008 Sep;34(5):261-5.
The impact of punctal occlusion on soft contact lens wearing comfort and the tear film.
Geldis JR, Nichols JJ.
Ohio State University, College of Optometry

OBJECTIVES: The purpose of this report is to describe the impact of punctal occlusion in symptomatic dry eye contact lens wearers and the relation between subjective and objective outcomes.

METHODS: This study was a randomized, controlled, double-masked, single center clinical trial. A previously described dry-eye questionnaire was used to determine subject eligibility. Tear interferometry was performed to evaluate prelens tear film thickness, contact lens center thickness, and postlens tear film thickness. Each subject was randomly assigned to receive the punctal plugs or a sham procedure. At the outcome examination, the subject completed the dry-eye questionnaire and answered one question rating the efficacy of the punctal plug treatment in addition to undergoing tear interferometry using an identical protocol as the first visit.

RESULTS: Nineteen subjects completed both visits of this study. There was a significant improvement in the dry-eye questionnaire scores from baseline to the outcome visit for both the plug (Z = -2.52, P=0.01) and sham groups (Z = -2.93, P=0.003). A significant increase in prelens tear film thickness occurred within the sham group from baseline to the outcome visit (Z = -1.96, P=0.05), but not for the punctal plug group. No other layers measured by interferometry were shown to change significantly for either group.

CONCLUSIONS: Results comparing the sham and plug groups were not significantly different from each other with regards to the questionnaire score and treatment benefit assessment, indicating either the treatment effect was not detected, although present, or punctal occlusion had no treatment effect at all.