title: Prelens tear stability: relationship to symptoms of dryness.
abstract: BACKGROUND
  Prelens tear thinning time (PLTTT) was used to quantify tear stability relative to symptoms of dryness.
  
  
  METHODS
  Twenty-two subjects were measured for PLTTT in this investigator-masked study. Specular reflection was performed, and the timed appearance of a colored interference fringe within the reflection under high magnification indicated PLTTT. Two symptom questionnaires were given: subjective evaluation of symptom of dryness (SESoD) and Ocular Surface Disease Index (OSDI).
  
  
  RESULTS
  The median PLTTT was 3.9 seconds for asymptomatic lens wearers. For those with dryness, the median PLTTT was 2.2 seconds. For SESoD, 69% of asymptomatic subjects had an average PLTTT of 3.0 seconds or greater. Eighty-three percent of symptomatic subjects had an average PLTTT of less than 3.0 seconds (P = 0.03). For OSDI, 71% of asymptomatic subjects had an average PLTTT of 3.0 seconds or greater. Seventy-five percent of symptomatic subjects had an average PLTTT of <3.0 seconds (P = 0.04).
  
  
  CONCLUSIONS
  The data suggest that a PLTTT breakup time of <3.0 seconds might be suitable criterion for tear film dysfunction causing dryness symptoms. PLTTT may be a rapid and useful clinical method for practitioners to provide a glimpse of self-reported symptoms caused by contact lens-related dryness.
authors.affiliation: Private Practice, Azusa, California, USA. eyemage@mminternet.com
authors.forename: Milton M
authors.initials: MM
authors.lastname: Hom
authors.forename: Adrian S
authors.initials: AS
authors.lastname: Bruce