Interpretation of tear film breakup
G. T. Vanley, I. H. Leopold and T. H. Gregg
Tear film breakup time (BUT) was measured in 25 normal subjects on 8
different occasions over a period of one month. Reproducibility of the BUT
test and factors involved in interpretation of tear film breakup were
studied. It was found that of 50 eyes, the average BUT ranged from five to
100 seconds, and that there were noticeable variations (P less than or
equal to .05) in an individual eye from one patient visit to the next. The
BUT is not a closely reproducible phenomenon in an individual eye.