Clinically, the diagnostic method of dry eye and adaptation of contact lens wearing have been the slit lamp examination, tear film break up time(BUT) measurement and Schirmer test. There have been many reports that Schirmer test and BUT measurement can be influenced by may factors, especially the mothods of measuring it. So the question of their repeatability and reproducibility has not yet been solved.

We studied the influence of contact lens wearing on the tear film phenol red thread test between contact lens wearers and non-wearers.

The results as follows:

1) The mean value measured by the PRT method was 13.92±7.68mm in right eye, 15.03±7.68mm in right eye, 21.48±6.30mm in left eye among the contact lens-non wearing group.

2) There was statistically significant decreased value of PRT in the contact lens wearing group.

3) There was not statistically significant difference between contact lens type, duration of contact lens wearing, duration of exchanging of contact lens, contact lens wearing time perone day.