title: Relative costs of various preserved artificial tear solutions for the treatment of dry eye conditions.
abstract: OBJECTIVE
  Tear substitutes are one of the primary treatment modalities for dry eye conditions. The goal of this research was to determine the least costly preserved artificial tear product for treating patients with mild dry eye conditions.
  
  
  METHODS
  Eight manufacturers' samples of artificial tears were examined to determine the effect of bottle angle on the dispensing drop size, the average drop volume, the number of drops per bottle, the measured volume of a bottle compared with its advertised volume, and the approximate cost per year for dry eye treatment. Drop sizes (mass) were determined by weighing to the nearest milligram. The retail cost was assessed to determine the most economical tear substitute.
  
  
  RESULTS
  For all samples tested, a smaller drop was produced when the bottle was held at a 45-degree angle as compared with a 90-degree angle from horizontal. At a 45-degree angle, Natural Tears Formula by Murine and Artificial Tears by Heath Pride produced the smallest drops, less than 0.030 g, closest to the volume of the lacrimal lake. Smaller drop size produced accordingly more drops per bottle. The measured total bottle volume averaged 3.5% more than the volumes stated on the labels. The most inexpensive sample based on cost per year of treatment was Natural Tears Formula by Murine at $11.29 annually.
  
  
  CONCLUSIONS
  Cost comparison of commercial over-the-counter artificial tears is an important factor to patients being treated for a dry eye condition. Several factors are important when considering the economics of article tear substitutes: drop size, number of drops per bottle, the volume of the bottle, and the cost of treatment per year. Because this information may not be readily available to patients, it is of great importance that physicians educate their patients to make treatment of dry eye as affordable as possible. The least expensive artificial tear treatments could require prolonged use of the same bottle, which may be associated with contamination of the contents of that bottle over time. The potential contamination with the long-term use of artificial tears in a bottle is significant. Patients using the least expensive artificial tear treatments should be advised against prolonged use of the same bottle.
authors.affiliation: Department of Ophthalmology, University of Tennessee College of Medicine-Chattanooga Unit, Chattanooga, TN, USA. rwenzenauer@pol.net
authors.forename: Robert W
authors.initials: RW
authors.lastname: Enzenauer
authors.forename: Anna
authors.initials: A
authors.lastname: Kao
authors.forename: Timothy
authors.initials: T
authors.lastname: Williams
authors.forename: R William
authors.initials: RW
authors.lastname: Lambert
mesh_terms: D016527:Drug Costs; D004349:Drug Packaging; D015352:Dry Eye Syndromes / Q000188:drug therapy / Q000191:economics*; D006801:Humans; D004366:Nonprescription Drugs / Q000008:administration & dosage / Q000737:chemistry / Q000191:economics*; D009883:Ophthalmic Solutions / Q000008:administration & dosage / Q000737:chemistry / Q000191:economics*; D010353:Patient Education as Topic; D011310:Preservatives, Pharmaceutical
chemical_list: D004366:Nonprescription Drugs; D009883:Ophthalmic Solutions; D011310:Preservatives, Pharmaceutical