Background: Hyperosmolarity of tear fluid has been recognised as a common feature of all types of dry eye disease. This study was designed to assess the inter-session reproducibility of a freezing point depression osmometer (Fiske 110) as the most common and precise way of measuring osmolality, by using two different volumes of tear samples on healthy subjects, and to determine the possible applications of this device in tear film research and clinical practice. Methods: Measurements were made by using the Fiske 110 osmometer under two different tear sample volumes (4 μl and 2 μl). In both cases, samples were diluted in purified water to obtain the 20 μl required by the device to perform the measurement (1:4 and 1:9 dilutions, respectively). Inter-session reproducibility was determined in two groups of 40 healthy subjects, in two sessions, one week apart. In each group, one of the two different tear sample volumes was used to determine the reproducibility of each technique. Results: No significant differences were detected between the measurements obtained in the two sessions using the 4 μl (paired t-test, p = 0.772; mean difference AE SD = −0.85 AE 18.77 mOsm/L; 95 per cent limits of agreement [LoAs] = −37.64/+35.94) or the 2 μl volume sample (paired t-test, p = 0.054; mean difference AE SD = 9.27 AE 29.44 mOsm/L; 95 per cent LoAs = −48.43/+66.97). Conclusions: Whereas both techniques show an acceptable inter-session reproducibility, the bias range with the present protocol was higher using the 2 μl tear sample volume than the 4 μl one. Therefore, it seems that the diluted 4 μl sample was the only dilution that could be acceptable for use in routine clinical practice for tear film analysis.
Purpose: Vital staining is one of the most widely test used to evaluate the corneal damage. The aim of this study was to assess the relationship of the corneal damage with tear meniscus height (TMH) and dry eye symptomatology. Material and methods: 530 subjects were recruited among patients of the Optometry Clinic (USC). Previously, all of them completed an OSDI questionnaire. Two videos of the ocular surface were recorded from each patient by a digital camera attached to a slit-lamp. Firstly, a video of central tear meniscus under 40x with the Tearscope device illumination was recorded. From those videos, a masked observer extracted one image and TMH was measured by using the ImageJ software. Secondly, after fluorescein instillation, the corneal surface was recorded by another experienced masked observer, who assigned a category to the corneal damaged based on the Oxford Scheme. The evaluation was stratified by corneal zones based on the CCLRU grading scales (central, superior, inferior, nasal and temporal). Results: When the sample was grouped by the corneal staining Oxford Grade, there was found a statistical difference between groups in OSDI and TMH value (ANOVA: both p≤0.006). There was found a difference in OSDI value when corneal damage was in nasal or inferior areas (t-test; both p≤0.015), and a difference in TMH value arises when damage was in the central, nasal or inferior areas (t-test; all p≤0.013). Conclusions: There is a relationship between corneal damage grade and corneal zones with dry eye symptomatology and tear film volume.
Purpose: Tear film hyperosmolarity is considered one the core mechanism of the dry eye along with the tear film stability. Many tear physiological variables oscillate during the day. This study was designed to assess the differences in tear film osmolarity between morning and afternoon in a group of healthy subjects.
Materials and methods: A total of 25 healthy subjects who fulfilled the study’s inclusion criteria were enrolled for the study. Tear osmolarity was measured using the TearLab™ system in two separated sessions, at 9.30 am and 6.30 pm. A paired t-test and a Bland–Altman test were used to assess the differences between sessions.
Results: Tear osmolarity (mean ± SD) was 309.96 ± 9.00 and 296.48 ± 12.98 mOsm/l at 9.30 am and 6.30 pm, respectively, being significantly lower at 6.30 pm than at 9.30 am (mean difference ± SD = 13.48 ± 8.69 mOsm/l; paired t-test; p < 0.001).
Conclusions: Tear film osmolarity does appear to have some influence by the time of day in healthy patients.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.