Intraobserver Repeatability Assessment of the S390L Firefly WDR Slitlamp in Patients With Dry Eye Disease: Objective, Automated, and Noninvasive Measures

Objectives:To assess the intraobserver repeatability of automated, objective, and noninvasive measures obtained with the S390L Firefly WDR slitlamp.Methods:This cross-sectional study included 50 eyes of patients with dry eye disease with a mean age of 55.06 & PLUSMN;12.96 years. Three consecutively repeated measures of the following variables were obtained: first noninvasive break-up time (F-NIBUT), average noninvasive break-up time (A-NIBUT), tear meniscus height, tear meniscus area (TMA), nasal ciliary hyperemia (NCIH), temporal ciliary hyperemia (TCIH), nasal conjunctival hyperemia (NCOH), temporal conjunctival hyperemia (TCOH), upper loss area meibomian gland (U-LAMG), lower loss area meibomian gland (L-LAMG), upper meibomian gland dysfunction grade (U-MGD grade), and lower meibomian gland dysfunction grade (L-MGD grade). Intraobserver repeatability was estimated with coefficient of variation (CoV), intrasubject standard deviation (SD) (S-w), and Bland-Altman plots.Results:All variables showed no statistically significant differences in the repeated-measures analysis except for L-MGD grade (P=0.045). F-NIBUT and A-NIBUT obtained the highest CoV with an average value of 0.48 & PLUSMN;0.41 [0.02-1.00] and 0.34 & PLUSMN;0.25 [0.02-1.00], respectively. The remaining variables showed CoVs between 0.04 & PLUSMN;0.11 [0.00-0.43] and 0.18 & PLUSMN;0.16 [0.00-0.75]. A-NIBUT, TMA, NCOH, and L-LAMG obtained an S-w of 2.78s, 0.21 mm(2), <0.001, and 4.11%, respectively. Bland-Altman plots showed a high level of agreement between pairs of repeated measures.Conclusion:The S390L Firefly WDR slitlamp has moderate intraobserver repeatability for F-NIBUT and A-NIBUT, which suggests that F-NIBUT and A-NIBUT are tests with high variability. The remaining variables show satisfactory intraobserver repeatability.

Automated summary

This study aimed to evaluate the intraobserver repeatability of automated, objective, and noninvasive measurements obtained with the S390L Firefly WDR slitlamp. Multiple variables were measured in 50 eyes of dry eye disease patients. The results showed that all variables except L-MGD grade had no statistically significant differences in repeated-measures analysis. F-NIBUT and A-NIBUT had the poorest repeatability, while the remaining variables showed satisfactory repeatability.