Abstract
Purpose :
It is believed that non-invasive breakup time (NIBUT) measured by tear interferometry such as DR-1α indicates the breakup of lipid layer of the tear film, and non-invasive Keratograph breakup time (NIKBUT) evaluated based on the changes of infrared illuminated topography pattern by Keratograph 5M indicates the breakup of the surface of tear film. Both measurement of NIBUT and NIKBUT was often disagreed although both measurement is the evaluation of surface condition of the tear film. To identify the cause of this disagreement between NIBUT and NIKBUT, we compared the measurements of both DR-1α and Keratograph 5M.
Methods :
One hundred twenty eyes in 60 subjects (19 males and 41 females, mean age 54.1 y-o, range 18-74 y-o) were enrolled in this clinical study. Based on the tear film parameters, all the subjects were classified into normal subjects, aqueous-deficient dry eye or meibomian gland dysfunction. DR-1α was applied to evaluate the lipid layer condition of the tear film, interferometric fringe pattern and NIBUT. Keratograph 5M was applied to identify the area where the tear film was firstly broken and to measure NIKBUT.
Results :
After the comparison between NIBUT and NIKBUT, the number of the eyes that NIBUT and NIKBUT were agreed was 42 eyes in 32 subjects (12 males and 30 females). Thirty-nine eyes in 29 subjects showed disagreement between NIBUT and NIKBUT. Among the disagreement subjects, NIKBUT was shorter than NIBUT in almost subjects with disagreement. Comparison of the observation of the lipid layer condition of the tear film by DR-1α and the firstly broken area by Keratogrgaph 5M revealed that the area of tear film breakup detected by Keratograph 5M was observed as thickened lipid layer detected as multi-colored interferometric fringe visualized by DR-1α. Thirty-nine eyes in 35 subjects showed no relationship between the area where Keratograph 5M detected as the firstly broken area and the surface condition of lipid layer of the tear film. Interferometric observation revealed that unmatched eyes included cosmetics’ contaminated, perfectly normal, evenly very thick, tilting on the lower 1/4 region or a very thin and unstable.
Conclusions :
NIBUT and NIKBUT were agreed under the condition of stable lipid layer of the tear film. Unstable surface condition of the lipid layer caused the disagreement of NIBUT and NIKBUT.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.