Changes caused by fluorescein in the tear film evaluated with hybrid break-up time test as a new method - Part Two:...

To examine the changes caused by fluorescein in the tear film by analyzing the qualitative parameters such as breakup location and also detailed quantitative parameters.

After determining the break-up time (BUT) value and breakup locations by the Non-invasive break-up time (NI-BUT) method, we re-evaluated the changes in the tear film stained with fluorescein using the topographical method. We called the topographic evaluation of the tear film stained with fluorescein as the Hybrid-BUT test. The results for the parameters obtained for each participant by the NI-BUT and Hybrid-BUT tests were compared.

Our study was conducted with 82 participants aged between 18 and 58 years (mean age 34.1 ± 11.1). The mean first break-up time value (BUT₁) was 4.1 ± 2.7 s on the NI-BUT test versus 5.1 ± 3.2 s on the Hybrid-BUT test (p = 0.029). The mean average of all break-up time values (BUT_Avg) for each participant was 7.2 ± 3.2 s on the NI-BUT test versus 8.4 ± 3.1 s on the Hybrid-BUT test (p = 0.004). After dividing the corneal surface into quadrants of 90°, there was no significant difference in the comparison of the locations of the first breakup (QUAD_{(First breakup)}), the second breakup (QUAD_{(2nd breakup)}) and the third breakup (QUAD_{(3rd breakup)}) between the two tests (p>0.05).

Fluorescein affects quantitative values rather than qualitative parameters in tear film. We observed that the change caused by fluorescein in tear film break-up time could be detected objectively and in a documented manner using Hybrid-BUT test.