Intrasession repeatability and interobserver reproducibility of ICP Tearscope measurements of tear meniscus height and non-invasive breakup time.

PURPOSE: To examine intrasession repeatability and interobserver reproducibility of tear meniscus height (TMH) and non-invasive tear breakup time (NIBUT) measurements provided by ICP Tearscope, and their agreement with Keratograph 5 M measurements in persons with and without dry eye.

METHODS

Participants were 48 individuals with dry eye disease (DED) and 44 healthy controls. To determine intrasession repeatability, two consecutive TMH and NIBUT measurements were carried out by a single experienced examiner using ICP Tearscope. For interobserver reproducibility, a second masked investigator measured TMH and NIBUT on the first image and video captured by the examiner. Keratograph 5 M measurements of both variables were carried out by the same examiner. Repeatability and reproducibility were evaluated through within-subject standard deviation (Sw), coefficient of variation (CoV), intraclass correlation coefficient (ICC) and Bland-Altman plots (bias and limits of agreement (LoA)).

RESULTS

The TMH measurement with ICP Tearscope showed both, a moderate intrasession repeatability (Sw = 0.045, CoV < 19.82 %, ICC > 0.684) and interobserver reproducibility (Sw = 0.032, CoV < 14.09 %, ICC > 0.926). The NIBUT measurement showed worse intrasession repeatability in the DED group (CoV = 27.53 %) than in the Control group (CoV = 13.31 %). Even though similar Sw, LoA and ICC values were observed in both groups (Sw = 2.55 s and 2.34 s; LoA = -6.60 to 5.18 s and -4.82 to 6.51 s, Control and DED respectively, ICCs > 0.95). Interobserver reproducibility indicated a moderate amount of variability with CoV ≤ 15.01 % recorded in both groups. Agreement between the two devices was poor. Limits of agreement were not clinically acceptable for TMH (LoA = -0.19 to 0.14 mm and -0.16 to 0.13 mm, Control and DED, respectively) and for NIBUT (LoA = -12.74 to 14.08 s and -12.19 to 12.87 s, Control and DED, respectively).

CONCLUSIONS

ICP Tearscope provides TMH and NIBUT measurements that show weak repeatability and moderate interobserver reproducibility. This device is not interchangeable with the Keratograph 5 M.