Evaluation of Tear Film Functions Preoperatively and Postoperatively in Cases with Pterygium: A Case Control Study

Abstract

Introduction: The presence of pterygium and dry eye symptoms often co-exist. Pterygium disturbs the tear film. The extent to which the excision of pterygium will affect the tear film needs to be evaluated. Tear-film Break Up Time (TBUT) and Schirmer’s I and II test are some of the common tests used for evaluation of the tear film. Aim: To study the effect of pterygium and pterygium excision surgery with conjunctival autograft technique on tear film. Materials and Methods: A hospital based case control study was conducted on 200 eyes of 100 patients from September 2017 to August 2019. The eye affected with pterygium was the case eye and the other normal eye of the same patient was taken as the control. TBUT, Schirmer’s I and II test were done preoperatively and postoperatively on day 10, 30 and 60. Statistical analysis was done using descriptive and inferential statistics using Student’s unpaired t-test and software used in the analysis was SPSS 22.0 version and GraphPad Prism 7.0 version and p<0.05 was considered as level of significance. Results: The mean TBUT preoperatively in the case eye was 9.71±1.35 seconds and in the control eye was 10.64±1.32 seconds. Their difference was statistically significant (p-value <0.0001). TBUT increased significantly postoperatively (p-value <0.0001). The mean Schirmer’s I preoperatively in the case eye was 13±2.47 mm and in the control eye was 14.54±2.45 mm. Their difference was statistically significant (p-value<0.0001). Postoperatively it increased significantly (p-value<0.0001). The Schirmer’s II test value preoperatively in the case eye was 9.85±2.33 mm and in the control eye was 10.44±2.54 mm. There was no significant difference between the two (p-value=0.08). No change was seen postoperatively. Conclusion: There was an increase in the TBUT and Schirmer’s I test in the case eye after pterygium excision. Preoperatively there was a significant difference between the case and control eye but after pterygium excision, no significant difference was seen between the two. This showed that ultimately, post pterygium excision, the case eye showed an increased stability of tear film which was comparable to the control eye.

Keywords

• mean basal secretion
• schirmer’s test
• tear film break up time
• tear film stability