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H. Liu, C. Begley, S. Srinivas; Spatial Repeatability and Temporal Progression of Tear Breakup Domains: What do they tell us about the mechanism? . Invest. Ophthalmol. Vis. Sci. 2004;45(13):3457.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: This study compared the spatial reoccurrence and temporal progression of tear break–up domains (TBUDs) in dry eye and normal subjects to gain insight into the mechanisms that precipitate tear break–up. Methods: Tear break–up was induced in 10 normal and 10 dry eye subjects by the Forced Eye Opening test, which involves keeping one eye open for as long as possible. Video imaging of tear film fluorescence was used to monitor the onset and progression of TBUDs, analog images were digitized, and tear fluorescence patterns were quantified to obtain the TBUD location and area. The overlap of TBUDs among 3 successive trials 5 minutes apart, and the progression of TBUDs during one trial were computed by MATLAB programs. Results: The average percent TBUD of the corneal surface measured just before the blink among the 3 trials in normal subjects was 11.3%±5.0% (range: 5.6% to 18.4%), which is significantly lower (t test, p=0.027) than dry eye subjects, who averaged 17.8%±7.0% (range: 8.0% to 32.0%). When the overlap of TBUDs from 3 successive trials was compared, normal subjects averaged 2.20%±2.99% (range: 0.08% to 8.43%) and dry eye subjects averaged 3.51%±4.12% (range: 0.80% to 13.31%). This difference was not significant (p=0.429). All dry eye subjects showed extensive central TBUDs, but overlaps were minimal. The TBUDs often developed in a linear pattern along the upper lid margin, or started where tear film was initially thinner. Central TBUDs began as dots or streaks, but the shape often changed as TBUDs "grew". Central TBUDs increased in area rapidly and began to coalesce in dry eye subjects. Conclusions: These quantitative methods allow us to closely track the events in tear break–up. TBUDs near the upper lid margin overlapped often in successive trials, which may be due to breakup around the "black line." However, central TBUDs showed little overlap, suggesting that it is a random event controlled by surface tension or lipid layer interactions with the ocular surface or debris.
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