The Changes of Tear Break-up Time and Schirmer's Test after Photore fractive Keratectomy

ABSTRACT

Myopic regression and corneal opacity are well known complications after photorefractive keratectomy(PRK)and some clinical reports suggest the postoperative dry eye syndrome make worse corneal opacity. To investigate the changes in tear secretion and tear film stability after excimer laser PRK for myopia we measured tear break-up time(BUT)and the Schirmer's test on 249 eyes of 126 persons ranging from -2 ~ -11 D(mean -5.40 D)at preoperative 1 month, 6 month and 1 year after PRK. The result shows that the Schirmer's test and BUT values are reduced together at 1 month after PRK, but BUT values return to almost normal levels at postoperative 6 months, whereas Schirmer's test values never come back to initial ones regredless of the presence of preoperative dry eye syndrome and refractive error. So we reach an idea that the decrease of tear secretion due to vague corneal sensation rather than the tear film instability from irregular corneal surface effects on the postoperative dry eye syndrome largely. From this results, we propose that artificial tears should be used at least for an year for the eyes after PRK.