Dry eye evaluation and correlation analysis between tear film stability and corneal surface regularity after small incision lenticule extraction

Abstract

To investigate the dry eye after small incision lenticule extraction (SMILE) and explore the correlations between changes in the tear film stability, the tear secretion and the corneal surface regularity. Sixty-two eyes of 22 men and 13 women who underwent SMILE were included in this study. Corneal topography was measured to assess the index of surface variance (ISV) and the index of vertical asymmetry (IVA). Dry eye tests including subjective symptom questionnaire, tear breakup time (TBUT), corneal fluorescein staining and Schirmer's test (ST) were evaluated before and at 1 and 6months postoperatively. TBUT was found to be significantly decreased from 9.8±3.4s preoperatively to 7.4±3.8s at 1month and 6.5±3.6s at 6months (both P<0.001). There was a significant decrease in ST at 1month postoperatively (P=0.012); however, ST returned to baseline by 6months (P=0.522). Both ISV and IVA significantly increased after the surgery (all P<0.001). In addition, the changes in TBUT were negatively correlated with the increases in ISV and IVA (r=-0.343, P=0.006 and r=-0.311, P=0.014, respectively). Patients undergoing SMILE might develop a short-TBUT type of dry eye. Corneal surface regularity indices might be helpful in the assessment of tear film stability following SMILE procedure.