Purpose: We explore the unique rheological and structural properties of human and bovine meibomian lipids to provide insight into the physical behavior of the human tear-film lipid layer (TFLL).
Methods: Bulk rheological properties of pooled meibomian lipids were measured by a commercial stress-controlled rheometer; a home-built interfacial stress rheometer (ISR) probed the interfacial viscoelasticity of spread layers of meibomian lipids. Small- and wide-angle x-ray scattering detected the presence and melting of dispersed crystal structures. Microscope examination under cross polarizers provided confirmation of ordered crystals. A differential scanning calorimeter (DSC) analyzed phase transitions in bulk samples of bovine meibum.
Results: Bulk and interfacial rheology measurements show that meibum is extremely viscous and highly elastic. It is also a non-Newtonian, shear-thinning fluid. Small- and wide-angle x-ray diffraction (SAXS and WAXS), as well as differential scanning calorimetry (DSC) and polarizing microscopy, confirm the presence of suspended lamellar-crystal structures at physiologic temperature.
Conclusions: We studied meibum architecture and its relation to bulk and interfacial rheology. Bovine and human meibomian lipids exhibit similar physical properties. From all structural probes utilized, we find a melt transition near eye temperature at which lamellar crystals liquefy. Our proposed structure for the tear-film lipid layer at physiologic temperature is a highly viscoelastic, shear-thinning liquid suspension consisting of lipid lamellar-crystallite particulates immersed in a continuous liquid phase with no long-range order. When spread over on-eye tear, the TFLL is a duplex film that exhibits bulk liquid properties and two separate interfaces, air/lipid and water/lipid, with aqueous protein and surfactantlike lipids adsorbed at the water/lipid surface.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1167/iovs.12-10987 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Sex-Based Differences in the Arthroscopic Treatment of Femoroacetabular Impingement Syndrome: 10-Year Outcomes With a Nested Propensity-Matched Comparison.
Am J Sports Med
January 2025
American Hip Institute Research Foundation, Des Plaines, Illinois, USA.
Background: Sex has been associated with different pathologic characteristics in painful hips undergoing hip arthroscopic surgery.
Purpose: To compare minimum 10-year patient-reported outcomes (PROs) and survivorship in patients who underwent primary hip arthroscopic surgery for femoroacetabular impingement syndrome and labral tears according to sex.
Study Design: Cohort study; Level of evidence, 3.
Mini-open transosseous repair with bursal augmentation improves outcomes in massive rotator cuff tears.
Sci Rep
January 2025
Department of Orthopedics and Traumatology, KasrAlAinyFacultyofMedicine, Cairo University, Al- Manial, Cairo, Egypt.
Treatment of Massive rotator cuff tears (MRCT) is difficult, with high rates of retears. Using biological augmentation in the form of the highly vascular subacromial bursa, was used to improve tendon healing. This work aimed to evaluate the results of arthroscopic guided mini-open transosseous repair with bursal augmentation in the treatment of MRCTs in a five-step approach.
View Article and Find Full Text PDFCorrelation between medial meniscus degenerative tears and medial meniscus extrusion and dynamics using ultrasonography.
J Orthop Sci
January 2025
Department of Orthopedic Surgery, Graduate School of Medical Science Kanazawa University, 13-1 Takara-machi, Kanazawa-city, 920-8641, Japan.
Background: Evaluating the correlation between degenerative meniscus tears and medial meniscus extrusion is necessary to determine the appropriate treatment plan for early-stage knee osteoarthritis. This study evaluated the relationship between degenerative meniscal tears and medial meniscus extrusion in early-stage knee osteoarthritis by using ultrasonography.
Methods: A total of 132 knees from 123 patients with early-stage knee osteoarthritis were evaluated retrospectively.
Assessing Surgical Competency Among Fellows in Vitreoretinal Surgery: A Survey of Fellowship Program Directors and Fellows.
Ophthalmol Retina
January 2025
Byers Eye Institute, Stanford University, Palo Alto, CA,. Electronic address:
Purpose: We surveyed vitreoretinal (VR) fellowship program directors (PDs) to elucidate how they assess surgical competency among VR fellows. In addition, we also surveyed fellowship program graduates for the years 2022 and 2023 regarding assessment metrics and tools used during VR fellowship training.
Design: Web-based, cross-sectional descriptive study.
A novel Schirmer Strip-Based Tear Matrix Metalloproteinase Measurement in Dry Eye Evaluation.
Ocul Surf
January 2025
Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences; Key Laboratory of Ocular Fundus Diseases, Chinese Academy of Medical Sciences. Electronic address:
Unlabelled: Dry eye disease is a multifactorial disorder of the ocular surface with increasing global prevalence, yet no universally accepted "gold standard" exists for its diagnosis or severity assessment. Tear matrix metalloproteinase 9 (MMP-9) is widely recognized as a valuable biomarker for dry eye, yet there remains a critical need for a simple, accurate, and broadly applicable method for its quantification. This study aims to develop and evaluate a Schirmer strip-based Eu-time resolved fluorescence immunochromatography (Eu-TRFICO) method for the quantitative detection of MMP-9 in tears.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!