Comparison of Schirmer test values between patients with aqueous deficient dry eye and healthy participants

Summary Purpose The present study aimed to compare the results of the Schirmer test over time between the eyes of healthy participants and those with aqueous-deficient dry eye (ADDE) and to calculate the diagnostic cut-off values. Methods An observational cross-sectional study was carried out with 20 healthy volunteers and 20 patients with ADDE who fulfilled the inclusion/exclusion criteria (40 eyes/group). A digital photograph was taken of each strip in both eyes simultaneously every minute during a Schirmer test procedure until the test ended (minutes 1, 2, 3, 4, and 5). Results from the strips were measured by a masked observer using ImageJ software and compared between the two groups. Results There was a difference in the Schirmer test results for the various time points in all analyses between the two groups (Greenhouse–Geisser, both p ≤ 0.001; Sidak, all p ≤ 0.001). In the pairwise analysis of each time point, there was a difference in Schirmer values between the groups (unpaired t test, all p ≤ 0.001). There was no inter-eye difference in Schirmer absolute values between time points for both groups (Friedman, both p ≥ 0.090; Wilcoxon, all p ≥ 0.062), except for the first vs. the fourth and fifth time points in the ADDE participants (Wilcoxon, both p ≤ 0.030). In the pairwise analysis of each time point, there was a difference in inter-eye absolute values between the groups (unpaired t test, all p ≤ 0.010), except for the fourth vs. the final time point (Mann–Whitney, both p ≥ 0.414). Conclusion A complete report of the progression of Schirmer test values over time and between the eyes of healthy participants and ADDE patients is presented here, along with the cut-off criteria for the different time points studied.