title: Plugs for occlusion of the lacrimal drainage system.
abstract: BACKGROUND
  Next to medical therapy, blockage of the lacrimal drainage system is the commonest form of treating dry eye. Rather than applying an artificial tear, the latter helps to preserve any remaining natural tear fluid, which by far has the best wetting and nutrient capacity for the ocular surface. A temporary block is usually induced by implants to tamponade on the level of the lacrimal puncta or canaliculi.
  
  
  METHODS
  A Medline search was performed with the keywords 'lacrimal drainage system, punctum, canaliculus, temporary occlusion, plug, dry eye, keratoconjunctivitis sicca' for the years 1986-2006. Plugs are a suitable treatment in patients with moderate or more severe disease. The characteristics of the devices used and procedures as well as the complications described were analyzed.
  
  
  RESULTS
  Criteria such as a lack of Schirmer strip wetting, ocular surface staining and the frequency of artificial tears instillation should be assessed prior to making the decision to occlude the lacrimal drainage. Lacrimal plugs made of silicone or a thermodynamic acrylic polymer, such as hydrogel, appear to be safe and effective, although each patient should be followed on a long-term basis to exclude alterations of the lacrimal system such as chronic inflammatory reactions, extrusion or migration, which may all lead to discomfort. High-frequency ultrasound as a non-invasive, simple diagnostic technique can be used to identify the type or position of plug or inflammatory reaction present.
  
  
  CONCLUSIONS
  Tamponade of the lacrimal drainage system is a simple procedure that is underused. Preserving natural tears by blocking the lacrimal drainage system can successfully maintain the integrity of the ocular surface and corneal transparency and visual acuity. In patients with moderate or severe dry eye, it is capable of improving quality of life and preventing loss of vision.
authors.affiliation: University Eye Hospital, Greifswald, Germany.
authors.forename: Frank H W
authors.initials: FHW
authors.lastname: Tost
authors.forename: Gerd
authors.initials: G
authors.lastname: Geerling
mesh_terms: D015352:Dry Eye Syndromes / Q000378:metabolism / Q000601:surgery*; D006801:Humans; D007765:Lacrimal Apparatus / Q000601:surgery*; D019736:Prostheses and Implants; D019919:Prosthesis Implantation / Q000379:methods*; D013666:Tears / Q000502:physiology