Punctal plugs are small devices which fit into the tear duct of the eye. The plug is designed to block the duct and prevent liquid draining from the eye to the nose. Punctal plugs are used to treat an eye disorder called dry eye when other treatments fail to work.
Dry eye is a disorder with several different causes, including environmental effects, reduced tear production by the tear glands, and production of low quality tears. Tears are made up of several different substances, including oils and mucus, which form a film over the eye and keep it moist. If tears are lacking in mucus or oils, the liquid may be too watery to properly protect the eye. This causes symptoms such as eye pain and itchiness, sensitivity to wind, light, and smoke, and visual disturbances. In such cases punctal plugs may be fitted to slow down liquid drainage.
There are several different types of punctal plugs. The standard punctal plug is fitted at the top of the tear duct, or puncta. For the patient, these provide an advantage in that they can be removed and replaced easily. The associated disadvantage is that plugs which are not properly fitted may be lost more easily as well. Another type of punctal plug, called an intracanalicular plug, is fitted within the canalicula, which is the tear duct itself. These are not easily removed or lost, but cannot be replaced at home.
Punctal plugs may be temporary or permanent. When temporary, they are made from collagen, and are fitted to determine whether a particular patient will derive any benefit from the plugs. If the plugs help prevent dry eye, the patient is then fitted with a set of plugs made from silicone or another synthetic material. These plugs will last several months, and are suitable for people who suffer from seasonal dry eye as well as people with a permanent version of the condition.
Plugs which are labeled as “permanent” are not always so. Permanent plugs may last a year or longer, but all plug users have around a 40% risk of losing a plug within the first six months of use. This is because plugs which are inserted in the puncta can spontaneously extrude themselves, an effect which tends to occur within the first three months of use. Another possible risk is that of discomfort at the plug site, which occurs in approximately 10% of cases. In these cases, the plugs may have to be removed and refitted to ensure they are of the right size and shape for the patient.