STUDIES ON ASSESSING TEAR FILM STABILITY IN REFRACTIVE ERRORS:A COMPARATIVE STUDY OF INVASIVE AND NON INVASIVE TECHNIQUE

ABSTRACT

Tear film is responsible for the perfectly smooth ocular surface which allows for clear vision. Tear film stability test, which can be carried out with invasive and non invasive technique, evaluates how long time it takes for the tears to stay on the ocular surface before it evaporates. The study was aimed at comparing tear film stability using the invasive and non invasive methods and  find the correlation among the refractive status of students of University of Benin. An observational study involving 50 participants which consisted of 12 males and 38 females within the age group of 20 to 30 years with a mean±standard deviation of 22.70 ± 1.89 years. Participants were ask to keep their eyes opened, then non invasive technique using the keratometer(Bausch and Lomb) was done and then immediately after, Fluorescein tear break up time was done.The data was analyzed using the statistical package for social sciences(SPSS) version 22.0 and additional statistical analyses were used to compare and find correlation between invasive and non invasive technique in people with refractive errors, and it showed  no statistically significant difference between invasive and non invasive tear break up technique.Additionally there was no correlation between tear film stability and refractive errors. This showed that refractive errorsdoes not influence tear stability. The overall mean of TBUT measured with non-invasive technique (16.88) was higher than that measured with invasive technique (15.46). This difference was not statistically significant p=0.251.So therefore any method can be used to assess tear film.This study will help optometrists know the type of refractive error more prone to tear film instability(evaporative dry eye) and a reliable, faster and effective method of diagnosing tear film stability in people with refractive errors.The accuracy of tear breakup time (TBUT) measurements can vary depending on several factors, including the specific technique used, the proficiency of the examiner, and the characteristics of the patient's tear film. In general, both invasive and noninvasive TBUT methods can provide valuable information about tear film stability, but they each have their strengths and limitations.

Keywords:  Tear stability, TBUT (Tear break up time), NIBUT (Non invasive break up time), Refractive errors.