Punctal Occlusion //
The inner nasal portion of each eyelid has a tiny opening called the punctum (pleural – puncta), which serves to drain tears from the surface of the cornea into the nose. Each person has a total of four puncta (one per eyelid). Drainage of tears through the puncta and tear drain canals allows for normal, constant flow of tears across the cornea into the nose. This normally prevents tears from building up excessively in the eyes which may result in blurred vision. The puncta also prevents tears from “overflowing” and running down the cheek, a condition called “epiphora”. However, certain conditions exist in which occlusion of the puncta may be beneficial. Dry eyes (inadequate tear production) is the most common condition in which punctual occlusion is performed. Other conditions which may benefit from punctual occlusion include exposure (the eyes dry out too rapidly due to incomplete or infrequent blink), or corneal ulcer or erosion (more lubrication would help speed the healing process). Punctal occlusion is performed to help prevent tears on the surface of the eye from draining into the nasal passages, and to thereby provide the most lubrication possible to the cornea and ocular surface. When the puncta are occluded, the tears that the patient’s own lacrimal gland produces (and the artificial tears that the patient applies) will NOT drain as readily through the puncta and into the nasal passages; hence tears will stay on the ocular surface longer, resulting in better lubrication of the cornea. Punctal occlusion also results in better absorption of eye drops into the eye and decreased systemic absorption. Punctal plugs are also often applied as a short term measure to treat various acute or transient conditions such as a corneal erosion or ulcer.
The puncta are occluded in various ways. Often, collagen plugs are initially applied to one, two, three, or all four puncta. This is a relatively simple, quick procedure. Tiny collagen implants (about the size of a grain of rice) permit only a portion of the tears to pass into the nose (a partial blockage), thus building up tears on the ocular surface. The implants will absorb within one to two weeks. This gives the patient and physician time to evaluate the effectiveness and comfort provided by the increased tears on the surface of the eye. Often, collagen plugs are placed as a “test”, to determine if punctal occlusion is helpful, before considering a more permanent procedure to occlude the puncta.
A silicone plug may also be placed in the puncta. Placement of a silicone plug results in complete blockage of tear drainage into the nose, and is permanent as long as it remains in place. Often the tiny punctum must be carefully dilated before the silicone plug can be successfully placed. At times the plug may extrude or fall out. Eventually, the silicone plug may be removed if it does not seem to help or if it results in excess tearing or irritation, though this is uncommon. The plug may easily be removed in the office. Rarely, complications such as infection or bleeding may occur.
Thermal occlusion of the puncta may also be performed. In this procedure, a small injection of local anesthetic is administered into the eyelids prior to the actual procedure. Thermal occlusion is then performed by inserting a cautery probe tip into the tear drainage canal. The heat causes the canal to be “sealed shut”. This results in complete, permanent blockage of the tear duct. One, two, or all four puncta may be thermally occluded. The advantage of this procedure is that it usually results in permanent occlusion of the tear duct. However, because it is permanent, this technique is often reserved for patients with severe, or chronic conditions.