Purpose: To evaluate the applicability of the fourth-generation OCULUS keratograph in measuring lower tear meniscus height.
Methods: Seventy cases (140 eyes) with dry eye disease and 37 controls (74 eyes) were enrolled. Tear breakup time (TBUT), Schirmer test I, and corneal fluorescein staining were examined. The images of lower tear meniscus were obtained by OCULUS keratograph. The tear meniscus height was measured and its correlation with traditional tear film diagnostic tests were analyzed.
Results: Using the hyper-reflective lines, the height of the tear meniscus was measured using the images of the OCULUS keratograph. For the inter-individual variation, the intraclass correlation coefficients and coefficient of variation values were 0.914 and 16.4%, respectively. For the intra-individual variation, the intraclass correlation coefficients and coefficient of variation values were 0.939 and 15.9%, respectively. The interobserver reproducibility and the intraobserver repeatability were for the control only. The average tear meniscus height value in dry eye disease group was 0.22 (0.19-0.24) mm, being significantly lower compared with 0.29 (0.26-0.34) mm in the control group (p<0.001). Tear meniscus height value had significantly correlation with TBUT and Schirmer test I (r=0.619 and 0.626, both p<0.001). The measurement of lower tear meniscus by OCULUS had lower individual variability and better repeatability.
Conclusions: OCULUS keratograph is a quick, noninvasive, and reliable method to measure lower tear meniscus, whose value has a significant correlation with traditional dry eye disease diagnostic tests.