Tear break-up time for tear film evaluation: Are moistening solutions interchangeable?

It was the main purpose of this study to investigate the influence of the moistening solution on TBUT measurements in an asymptomatic population.

An online survey was employed to determine the compliance of Spanish eye care practitioners with the recommended normalized procedure to administer TBUT. For the purpose of examining the clinical relevance of discrepancies from the recommended procedure, a randomized, double-masked, bilateral study was designed in which a micropipette was used to moisten fluorescein strips with a controlled volume of six different solutions, commonly available in the contact lens office, and TBUT was measured in 58 non-dry eye (OSDI<15) subjects (age from 19 to 32 years).

Results from the online survey revealed that 64% of Spanish practitioners frequently use (or have used) different solutions to moisten fluorescein strips during TBUT assessment. Statistically significant differences in TBUT values were found between the various solutions as a whole (χ(2)=198.384, p<0.001), as well as between all solutions when explored pair-wise (all p<0.001), except for the two saline solutions.

The present findings support the relevance of selecting the appropriate solution when conducting TBUT for the evaluation of the tear film. Deviations from the recommended procedure may result in misdiagnosis of dry eye and unnecessary patient referral.