subject: Punctal Plugs And Pinguecula [print this page] Dry eye is an ocular disease often found among the elderly, contact lens users, and people whose tear film quality is damaged by drugs or external factors. When its symptoms are not sufficiently eliminated by specially formulated artificial tears and specially formulated ointments, non-drug methods may be chosen.
The next alternative for treatment is often the technique of closing the entrance to the tear duct (also called the 'punctum') with specially designed tear duct plugs, or punctal plugs. Each eye has two channels, located on the upper and lower eyelid corners near the nose. Tears usually flow from the tear glands and find their way into the nasal cavity through the tear ducts.
Punctal plugs serve to crimp or even totally block the outflow of tears from the eyes. By plugging this movement, tears will remain for a longer time on the surface of the eye. This increases the volume of tears in the eye, helping relieve dry eye manifestations and lengthen the stay of externally-applied artificial tears. The closure of the tear drainage channel is called punctal occlusion (blockage) in medicine, and it may be temporary or permanent.
Temporary tear duct occlusion refers to the treatment where the closing action can be undone and the plugs can be removed, when deemed helpful. Temporary closure means installing tear duct plugs that can be absorbed into the body (e.g. made from collagen, gelatine, and catgut) or plugs that cannot be absorbed (e.g. made from silicone, Teflon, etc.) Temporary closure is tested as an interim technique, to determine if blocking the tear ducts will reduce dry eye symptoms and also to test the possibility that the blocking action will induce too much build-up of tears in the eyes. Initially, all four tear duct openings are blocked with plugs. If the blocking action leads to excess tearing, the upper plugs are removed and, after several more days, the plugs in the lower tear ducts are also pulled out if recommended.
Punctal plugs are produced in two styles. One plug type totally blocks tear flow and it is located at the mouth of the tear duct. The second plug type is intended to regulate tear outflow and is usually implanted into the tear duct channel.
Tear duct plugs for temporary use are manufactured in several diameter-sizes, usually ranging from 0.2mm up to 2.8mm. The narrower diameters are used for installation into the tear duct channel. Ordinary absorbable tear duct plugs may last up to two weeks, which allows sufficient time for observation on their effects. There are more durable kinds made of synthetic but still absorbable material, which can last 2-6 months.
Some people refer to occlusions using non-dissolvable tear duct plugs as semi-permanent occlusions, but the plugs are still removable. Permanent procedures are another matter. They are not reversible because the tear ducts are permanently sealed by cauterisation ('burning') with a battery-operated or electric heat-producing device or laser photocoagulation ('welding'). Laser welding offers an added benefit in that it can be set up to produce just enough burns (or weld spots) to minimise tear flow without totally closing the tear duct. However, experience has shown that non-laser cauterisation is more effective in the long-term. There are also surgical methods to permanently block the tear ducts. Whatever technique is utilised for permanent occlusion, the basic principle is the creation of permanent and thorough scarring into the tear duct channels to block tear outflow..
Permanent closure is conducted only when it becomes certain that blocking the tear ducts will minimise dry eye symptoms and will not induce too much tears. Permanent closure has an advantage over tear duct plugs. It is not unusual for tear duct plugs to come off without warning, and the probability of plug loss increases with each subsequent replacement. This risk is removed with permanent occlusion.
