A punctal plug (tear duct plug) is a small medical device that is inserted into the tear duct (puncta) of an eye to block the duct. This prevents the drainage of liquid from the eye. They are used to treat dry eye.
Permanent punctal plugs are usually made of silicone. These are available in various sizes. For maximum effectiveness, the largest size that fits should be used. These are more effective than collagen plugs. They can sometimes become loose and fall out, in which case they can be replaced.
Some plugs are made of thermally reactive material. Some of these are inserted into the punctum as a liquid and then they harden and conform to the individual's drainage system. Others start out rigid and become soft and flexible, adapting to the individual's punctal size after they are inserted.
The risks of punctal plugs are fairly small. There is a risk of eye irritation, excessive tearing, and, in rare cases, infection. Some doctors require a disclaimer to be signed prior to the insertion of a plug.
A large silicone plug can cause slight pain upon blinking after insertion. This discomfort may stop within a week.
A systematic review by the Cochrane Collaboration sought to assess the safety and efficacy of punctal plugs for the management of dry eye. The review included seven studies, testing both collagen and silicone plugs. Overall there were mixed results; limited evidence showed that interventions involving permanent silicone or combined silicone/collagen punctal occlusion showed some evidence of clinical efficacy providing symptomatic relief to dry eye.  Some adverse outcomes from participants included spontaneous plug loss, epiphora, ocular irritation, foreign body sensation, and local inflammatory reaction.
If punctal plugs are at least partly effective, thermal or electric cauterization of puncti can be performed. Such cauterization is reversible and is effective for about two years, after which time the puncta are likely to naturally regrow and reopen. Cauterization can then be repeated. It offers complete closure of the duct for this period. It also obviates the need for a replacement plug when it falls out.
- Michelle Meadows (May–June 2005). "Dealing with Dry Eye". FDA Consumer Magazine. U.S. Food and Drug Administration. Archived from the original on February 23, 2008.
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- Ervin AM, Wojciechowski R, Schein O (2010). "Punctal occlusion for dry eye syndrome". Cochrane Database Syst Rev 9: CD006775. doi:10.1002/14651858.CD006775.pub2. PMC 3729223. PMID 20824852.
- "Dry eyes". Mayo Clinic. Mayo Foundation for Medical Education and Research. 2006-06-14. Retrieved 2006-11-17.