A Standard Method of Measuring Tear Film Break-Up Time in Normal Subjects

ABSTRACT

The tear film break-up time test is a useful diagnostic test for dry eye syndrome,but it shows a wide range of results in normal subjects according to many factors, especially the methods of measuring it. We studied the factors having some influences on B.U.T. and tried to find out a standard method of measuring B.U.T. in normal subjects. The results were as follows 1. The subjects were healthy without any ocular disease or symptoms. Total subjects were 200 persons, 400 eyes. 2. The standard method of measuring B.U.T. was as follows a drop of 0.125% sodium fluorescein was applied into the conjunctival sac and the patient was allowed to blink for at least 1-2 minutes. The tear film was then scanned without holding the lids, using the slit lamp beam, 4-5mm in width. 3. The mean B.U.T. measured by the standard method was 20.35 +/- 6.45 sec in normal subjects. 4. The mean B.U.T. was 18.17 +/- 8.02'sec in the group using fluorescein paper, 9.68 +/- 6.19 sec in the group blinking just 4-5 times,16.54 +/- 8.32 sec in the group measured holding the lids with the fingers, and 18.36 +/- 7.95 sec in the group using a broad beam. 5. There were statistically significant decreases of B.U.T. in the group blinking just 4-5 times and in the group measured holding the lids with the fingers.