title: Evaluation of the frequency of ophthalmic solution application: washout effects of topical saline application on tear components.
abstract: OBJECTIVE
  To determine and compare the effects of single and frequent topical applications of saline solution on tear protein concentration in clinically normal subjects.
  
  
  METHODS
  Tears were collected from both eyes of 11 normal volunteers using Schirmer's strips. Saline solution (0.9% sodium chloride) was applied once in the right eye and five times with an interval of 1 min each in the left eye. Tears were collected before and 5, 15, 30 and 60 min after application of the solution. Total tear protein concentration in the samples was measured by the Bradford method and major tear protein concentration (secretory immunoglobulin A, lactoferrin, lipocalin-1, lysozyme and sialic acid) was measured using a high-performance liquid chromatography assay.
  
  
  RESULTS
  A significant decrease was observed in the concentration of total tear protein, major tear proteins and sialic acid after topical application of saline solution. This decrease was attributed to the washout and dilution effect. A low protein concentration persisted longer with more frequent application of the solution. The concentration of secretory immunoglobulin A and sialic acid concentration recovered slowly compared with that of other proteins.
  
  
  CONCLUSIONS
  Even a single application of saline solution resulted in significant changes in major tear protein and sialic acid concentration in the tears of normal subjects. Differences in the recovery of tear protein concentration may be related to the process of protein production and secretion. A balance between normal tear function and the therapeutic effects of ophthalmic solutions should be considered when deciding the frequency of application, particularly in patients with dry eye.
authors.affiliation: National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Meguro-ku, Tokyo, Japan. shigeyasuchika@kankakuki.go.jp
authors.forename: Chika
authors.initials: C
authors.lastname: Shigeyasu
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Hirano
authors.forename: Yoko
authors.initials: Y
authors.lastname: Akune
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mochizuki
authors.forename: Masakazu
authors.initials: M
authors.lastname: Yamada
mesh_terms: D000287:Administration, Topical; D000328:Adult; D002851:Chromatography, High Pressure Liquid; D005136:Eye Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000378:metabolism; D007781:Lactoferrin / Q000378:metabolism; D054835:Lipocalin 1 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009113:Muramidase / Q000378:metabolism; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D009883:Ophthalmic Solutions / Q000008:administration & dosage*; D012965:Sodium Chloride / Q000008:administration & dosage*; D013666:Tears / Q000378:metabolism*; D013997:Time Factors
chemical_list: D005136:Eye Proteins; D007071:Immunoglobulin A, Secretory; C518443:LCN1 protein, human; D054835:Lipocalin 1; D009883:Ophthalmic Solutions; C042434:tear proteins; D012965:Sodium Chloride; D009113:Muramidase; D007781:Lactoferrin; D019158:N-Acetylneuraminic Acid