title: Time course of changes in tear meniscus radius and blink rate after instillation of artificial tears.
abstract: OBJECTIVE
  Using a novel digital meniscometer (PDM), alterations in tear meniscus radius (TMR) were measured simultaneously with blink rate (BR) following the instillation of artificial tears.
  
  
  METHODS
  Central TMR and BR of 22 subjects (11 male and 11 female; mean age, 24.3 ± 2.6 SD years) were measured at baseline, and 0, 1, 5, 10, and 30 minutes after instillation of an artificial tear containing hydroxypropyl-guar and glycol (SYS) or saline (SAL). A dose of 35 μL was applied in one eye in a randomized order with a washout period between each drop.
  
  
  RESULTS
  For SAL, compared to baseline TMR (0.33 ± 0.08 mm), TMR significantly increased with drop instillation (1.55 ± 0.69 mm) and at 1 minute (0.66 ± 0.36 mm; P < 0.05), but returned to baseline after 5 minutes. For SYS, TMR (0.32 ± 0.07 mm) remained significantly increased after application (1.62 ± 0.81 mm), and at 1 minute (0.81 ± 0.43 mm) and 5 minutes (0.39 ± 0.08 mm; P < 0.05). Compared to baseline BR with SAL (14.8 ± 7.7) and SYS (14.9 ± 9.4), values were significantly increased upon drop instillation (22.5 ± 11.8; 21.3 ± 11.8; P < 0.05), but returned to baseline after 1 minute. Dry eye symptoms were correlated with baseline BR (r = 0.550, P = 0.008).
  
  
  CONCLUSIONS
  Results indicate that PDM can detect changes in TMR following instillation of artificial tears. Difference in residence time reflects the different viscosity of each drop. An overload with a large drop may result in an initially increased BR.
authors.affiliation: School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom Höhere Fachschule für Augenoptik Köln (Cologne School of Optometry), Cologne, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Bandlitz
authors.affiliation: School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom.
authors.forename: Christine
authors.initials: C
authors.lastname: Purslow
authors.affiliation: University of Waterloo, School of Optometry and Vision Science, Waterloo, Canada.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Murphy
authors.affiliation: School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom Dr. Heiko Pult - Optometry and Vision Research, Weinheim, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Pult
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001767:Blinking / Q000187:drug effects*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D015352:Dry Eye Syndromes / Q000188:drug therapy*; D005260:Female; D006801:Humans; D008297:Male; D009883:Ophthalmic Solutions / Q000494:pharmacology*; D013666:Tears / Q000187:drug effects*; D013997:Time Factors; D055815:Young Adult
chemical_list: D009883:Ophthalmic Solutions
keywords: artificial tears; blink rate; dry eye symptoms; portable digital meniscometer; tear meniscus; tear volume loss