Evaluation of tear film stability before and after laser in situ keratomileusis.

OBJECTIVE

The study was conducted to evaluate tear film stability and tear secretion before and after laser in situ keratomileusis.

MATERIALS AND METHODS

It was a prospective, longitudinal and non-comparative analysis of clinical data of 20 consecutive myopic patients (40 eyes) collected before and after laser in situ keratomileusis. Assessments included tear secretion (Schirmer I and II), fluorescein tear break up time and ocular surface staining.

STATISTICS

The statistical package for social science (SPSS 10.0) was used for data analysis. The parameters of tear secretion and tear stability were analyzed using the paired and unpaired Student t-tests.

RESULTS

Schirmer II was reduced at seven days (9.5 ± 4.30 mm) and one month (10.3 ± 3.06 mm, p=0.001) after operation from the pre-operative value of 16.12 ± 3.90 mm. Tear film stability significantly decreased at seven days (6.79 ± 3.05 sec, p Less than 0.001) and one month (8.03 ± 2.81secs, p less than 0.001) from its pre-operative value (12.68 ± 2.69 secs). 87.5% had tear film instability (FBUT less than 10secs) seven days after surgery; it was reduced to 75 % at one month and 27.5 % at three months. It was 7.5 % before surgery. Corneal staining score was increased significantly at seven days (1.42 ± 1. 58, p less than 0.01) and one month (0.95 ± 1.41, p=0.02), from the pre-operative score of 0.17 ± 0.44.

CONCLUSION

Laser in situ keratomileusis significantly alters the tear film stability, Schirmer values and corneal staining at least for three months.