A punctal plug, also known as tear duct plug or lacrimal 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.
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Artificial tears are usually still required after punctal plug insertion.
Types
A temporary punctal occlusion can be inserted and tried first. These are made of collagen and are dissolvable. This is to ascertain that permanent ones will not cause excessive tearing.
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 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.
Risks
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.
Efficacy
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.
Alternatives
If punctal plugs are at least partly effective, thermal, electric or radiofrequency cauterization of puncti can be performed with local sedation. Depending upon the depth of the cauterization, it is effective for a few months to a few years, by which time the puncta are gradually likely to regrow and reopen. Cauterization can then be repeated. It initially offers complete closure of the duct. It also obviates the need for a punctal plug.