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.
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.