Applying a dual-Scheimpflug camera to measure tear film thickness

Abstract

Purpose: To assess the tear film thickness in healthy individuals by using a dual-Scheimpflug camera and topical 0.1% fluorescein. Methods: A prospective study on healthy individuals who underwent a bilateral tomography examination using the GALILEI dual-Scheimpflug with assessments of the thinnest and central corneal thickness (TCT and CCT, respectively), at baseline and 1 min after applying 2 and 4 µl of 0.1% fluorescein (30 min apart) under topical anesthesia with Oxybuprocaine 0.4%. Inclusion criteria were lack of dry eye disease symptoms and exclusion criteria were contact lens usage, eye drops usage, previous refractive surgery or any ocular surgery. All individuals scored zero on the ocular surface disease index (OSDI) questionnaire. Results: A total of 62 eyes of 31 participants were included in this study. The mean age was 35.3 ± 10.88 (range 18–62). The mean TCT in was 549.16 µm in the right eye (RE) and 547.84 µm in the left eye (LE). After instillation of 2 µl of 0.1% fluorescein mean TCT increase by 27.84 µm in the RE and by 26.35 µm in the LE. CCT change was 27.58 µm increase in RE and 27.23 µm increase in LE. After instillation of 4 µl of 0.1% fluorescein the mean increase in TCT and CCT were 30.09 and 30.26 µm for OD and 28.33 and 30.15 µm for OS respectively. Comparison between the post instillation of 2 and 4 µl measurements showed no significant differences. Conclusion: Combining a dual-Scheimpflug camera and 0.1% fluorescein may serve as a method to assess the pre-corneal tear film.