Human Lacrimal Production Rate and Wetted Length of Modified Schirmer's Tear Test Strips

Abstract

Purpose To assess and compare the wetting kinetics of sheathed and unsheathed Schirmer's tear test (STT) strips, and to determine the repeatability of 5-minute wetted length (WL) and basal tear production rate (BTPR). Methods Seventeen subjects underwent two sheathed and unsheathed STTs each for both eyes on four visits on separate days. After administration of topical anesthetic, WLs were measured every 30 seconds for 5 minutes, and BTPRs were calculated for sheathed strips. Limits of agreement (LoA), difference-versus-mean plots (DVM), and the coefficient of repeatability (CR) assessed WL and BTPR repeatabilities. Variance estimates were used to calculate sample sizes for future study. Results For the unsheathed STT, the mean (SD) difference in WLs between visits was 0.74 (5.05) mm, LoA were [−9.17, 10.64], and CR was 9.17 mm; for the sheathed STT, the mean (SD) intervisit difference was 0.16 (5.94) mm, LoA were [−11.49, 11.8], and CR was 10.53 mm. Eight of 48 sheathed STTs and 20 of 44 unsheathed STTs showed constant WL for the final 90 seconds of the test. The mean (SD) difference between repeated visits for BTPR was approximately 0.0 μL/min, LoA were [−1.82, 1.82], and CR was 1.91 μL/min. Conclusions Repeatability of sheathed and unsheathed 5-minute WL and BTPR is inadequate for measuring within-subject changes, but is sufficient for group studies with moderate sample sizes. Constant WL for the final 90 seconds with the eight sheathed STT measurements suggests varying BTPR, whereas constant WL with the unsheathed STT can be explained by balancing evaporation and BTPR. Translational Relevance Repeatability of the modified STT is evaluated clinically to establish quantitative BTPRs rather than inference from a strip WL.

Meibomian Gland Contrast Sensitivity and Specificity in the Diagnosis of Lipid-deficient Dry Eye: A Pilot Study

“…Schirmer's I test remained nondiscriminatory between groups, in agreement with published works that have shown the limitations of Schirmer's I test. [21][22][23][24] The variances of meibomian gland and fluorescein tear breakup time are vastly different between study groups, whereas other parameters remain similar between groups. The large variability of meibomian gland atrophy is, in part, responsible for why it is not a good discriminator.…”

NGLY1 deficiency: Novel patient, review of the literature and diagnostic algorithm

“…Brain MRI imaging was normal. Ophthalmic examination was normal except for hypolacrimia on Schirmer II testing . Electrocardiographic and echocardiographic results were normal.…”

The HYLAN M Study: Efficacy of 0.15% High Molecular Weight Hyaluronan Fluid in the Treatment of Severe Dry Eye Disease in a Multicenter Randomized Trial

“…This variation emphasizes the difficulty of judging the ocular surface condition from surface staining intensity. Similar fluctuations such as the one experienced for CFS are known for other dry eye signs [17,52,[57][58][59][60][61][62][63]. Originally enthusiastically welcomed as a highly reliable parameter for DED and used as a major decision maker with respect to the severity of DED, the diagnostic significance of tear osmolarity determined in the lower tear meniscus has recently been questioned [64].…”