Abstract: Upper vs. lower plugs (collagen only)

I would REALLY like to see this study replicated with 3-month or 6-month plugs. Personally I don't really have all that much faith in collagen plugs as a proxy for what longer term plugs will do, both from personal experience and patient reports.

Upper punctal occlusion versus lower punctal occlusion in dry eye.
Invest Ophthalmol Vis Sci. 2010 May 12. [Epub ahead of print]
Chen F, Wang J, Chen W, Shen M, Xu S, Lu F.
School of Ophthalmology and Optometry, Wenzhou Medical College, Wenzhou, China.

Purpose: To compare the effect of upper punctal cclusion and that of lower punctal occlusion in dry eye patients.

Methods: Occlusion of one eye's upper punctum and the contralateral eye's lower punctum with collagen plugs was performed in 20 dry eye patients. The same procedure was done in 20 normal subjects. The upper and lower tear menisci were imaged simultaneously by real-time OCT before punctal occlusion and repeated on days 1, 4, 7 and 10 afterwards. The subjective symptom scoring, corneal fluorescein staining, Schirmer I test, and tear break-up time (TBUT) were also performed.

Results: In dry eye patients, occlusion of either punctum improved symptom scores, fluorescein staining scores, TBUT, and lower tear meniscus height (LTMH, P < 0.05); however Schirmer test scores and upper tear meniscus height (UTMH) did not change after occlusion(P > 0.05). There was no significant difference for any of these variables between upper punctum occluded eyes and lower punctum occluded eyes before or after occlusion (P > 0.05). In normal subjects, Schirmer test scores, TBUT, UTMH, and LTMH did not change over time (P > 0.05).

Conclusion: Punctal occlusion with collagen plugs in dry eye patients leads to the relief of subjective symptoms and the improvement of objective signs. The effectiveness of occluding upper or lower punctum is similar. The LTMH is a valid indicator for the success of the punctal occlusion.