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Keywords = tear trough

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20 pages, 10823 KB  
Review
Anatomical-Based Filler Injection Diagnosis to Treatment Techniques: Infraorbital Groove and Hollowness
by Gi-Woong Hong, Wonseok Choi, Song-Eun Yoon, Jovian Wan and Kyu-Ho Yi
Life 2025, 15(2), 237; https://doi.org/10.3390/life15020237 - 5 Feb 2025
Cited by 1 | Viewed by 15748
Abstract
Infraorbital groove and hollowness are common aging-related anatomical changes in the periorbital region, leading to a sunken and tired appearance. These conditions are caused by the progressive loss of volume in the deep fat pads, including the sub-orbicularis oculi fat (SOOF) and malar [...] Read more.
Infraorbital groove and hollowness are common aging-related anatomical changes in the periorbital region, leading to a sunken and tired appearance. These conditions are caused by the progressive loss of volume in the deep fat pads, including the sub-orbicularis oculi fat (SOOF) and malar fat, along with skin thinning and decreased elasticity. Filler injections, particularly hyaluronic acid-based fillers, are the preferred treatment to restore volume and smooth the under-eye area. Proper diagnosis, understanding of anatomical variations, and accurate injection techniques are essential to avoid complications and achieve natural, esthetically pleasing outcomes. Treatments should consider the patient’s unique anatomy and potential adjunctive procedures to ensure balanced and harmonious facial rejuvenation. Full article
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16 pages, 8099 KB  
Guidelines
Best Practices for the Use of High-Frequency Ultrasound to Guide Aesthetic Filler Injections—Part 2: Middle Third of the Face, Nose, and Tear Troughs
by Roberta Vasconcelos-Berg, Stella Desyatnikova, Paula Bonavia, Maria Cristina Chammas, Alexander Navarini and Rosa Sigrist
Diagnostics 2024, 14(22), 2544; https://doi.org/10.3390/diagnostics14222544 - 13 Nov 2024
Cited by 5 | Viewed by 6858
Abstract
The midface is a key area in facial aesthetics, highly susceptible to age-related changes such as fat pad absorption, bone resorption, and loss of skin elasticity. These changes lead to the formation of prominent folds, such as the nasolabial fold. In addition, critical [...] Read more.
The midface is a key area in facial aesthetics, highly susceptible to age-related changes such as fat pad absorption, bone resorption, and loss of skin elasticity. These changes lead to the formation of prominent folds, such as the nasolabial fold. In addition, critical vascular structures and non-vascular components, such as the facial artery, angular artery, and parotid gland, make this region prone to complications during filler injections. High-frequency ultrasound (HFUS) offers real-time, radiation-free visualization of facial anatomy, enabling injectors to accurately target the desired treatment planes and avoid critical structures. This article is the second in a series of articles on ultrasound-guided facial injections and focuses on the midface. It provides a detailed overview of the sonographic anatomy of key areas, including the nose, tear trough, nasolabial fold, zygomatic, and preauricular regions. Step-by-step techniques for ultrasound-guided filler injections are described, emphasizing the importance of scanning both before and during injections to ensure safe filler placement. By using ultrasound in this area, injectors can possibly minimize risks such as vascular occlusion and other complications, such as the Tyndall effect and intra-parotid injection. With ongoing advancements, ultrasound-guided injections are expected to become more refined, enhancing both aesthetic outcomes and patient safety. Full article
(This article belongs to the Special Issue Ultrasound in the Diagnosis and Management of Skin Diseases)
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10 pages, 218 KB  
Review
Surgical and Non-Surgical Approach for Tear Trough Correction: Fat Repositioning Versus Hyaluronic Acid Fillers
by Stylianos Christodoulou, Argyrios Tzamalis, Ioannis Tsinopoulos and Nikolaos Ziakas
J. Pers. Med. 2024, 14(11), 1096; https://doi.org/10.3390/jpm14111096 - 6 Nov 2024
Cited by 2 | Viewed by 8001
Abstract
Objective: This paper compares two popular techniques for tear trough correction—fat repositioning and hyaluronic acid (HA) fillers—highlighting their efficacy, safety profiles, patient satisfaction, and associated complications. Methods: A narrative review of 20 studies comparing fat repositioning and HA fillers was conducted, [...] Read more.
Objective: This paper compares two popular techniques for tear trough correction—fat repositioning and hyaluronic acid (HA) fillers—highlighting their efficacy, safety profiles, patient satisfaction, and associated complications. Methods: A narrative review of 20 studies comparing fat repositioning and HA fillers was conducted, focusing on parameters such as duration of results, volume restoration, complication rates, and patient satisfaction. Results: Fat repositioning provides long-lasting results but carries higher surgical risks compared with HA fillers. The transconjunctival approach is suitable for patients with minimal skin excess. The supraperiosteal plane allows for a quicker procedure and, despite postoperative edema and temporary irregular contouring, shows no difference in final cosmetic outcomes compared with other planes. Internal fixation reduces the risk of fat relapse and skin scarring but carries the risk of suboptimal positioning. HA fillers offer immediate, minimally invasive results but require periodic maintenance. The use of a cannula reduces the risk of vascular occlusion. Combining a high G’ filler for the midface with a low G’ with low hydrophilicity for the tear trough reduces the amount of filler needed and prolongs the results. Both surgical and non-surgical methods are effective, depending on patient needs and anatomical considerations. Conclusions: Fat repositioning is ideal for patients seeking long-term correction and are willing to undergo surgery, while HA fillers suit those preferring non-invasive treatments with customizable, short-term effects. Both techniques have pros and cons that must be matched to patient goals and conditions. Full article
12 pages, 3164 KB  
Article
Surface Chemistry Study of Normal and Diseased Human Meibum Films Prior to and after Supplementation with Tear Mimetic Eyedrop Formulation
by Petar Eftimov, Norihiko Yokoi, Kazuhiro Tsuji, Kyoko Takahashi, Miho Nishiyama, Nikola Peev, Ani S. Koeva and Georgi As. Georgiev
Appl. Sci. 2024, 14(8), 3339; https://doi.org/10.3390/app14083339 - 15 Apr 2024
Cited by 2 | Viewed by 2096
Abstract
Ophthalmic nanoemulsions that can treat the deficiencies of meibum (MGS) in Meibomian gland disease and restore its functionality in the tear film are greatly sought. The Rohto Dry Aid (RDA) formulation employs TEARSHIELD TECHNOLOGYTM, which uses a multicomponent oil phase of [...] Read more.
Ophthalmic nanoemulsions that can treat the deficiencies of meibum (MGS) in Meibomian gland disease and restore its functionality in the tear film are greatly sought. The Rohto Dry Aid (RDA) formulation employs TEARSHIELD TECHNOLOGYTM, which uses a multicomponent oil phase of polar and non-polar lipid-like molecules selected to mimic the profiles of healthy meibum. Thus, the interactions of RDA with “diseased” Meibomian (dMGS) films merit deeper analysis, as these interactions might offer important clues for both the development of new ocular formulations and the processes behind the therapeutic action of the nanoemulsions. Pseudobinary dMGS/RDA films were spread at the air–water surface of the Langmuir trough. Surface pressure-area isocycles and stress relaxations were used to access the layer’s response to blink-like cycling and dilatational viscoelasticity, respectively, while film morphology was recorded via Brewster angle microscopy. It was found that RDA is able to reverse the brittleness and to restore the stability of “diseased” MGS films and thus to revert the layer’s properties to the functionality of healthy Meibomian lipids. Therefore, in order to effectively treat dry eyes with MGS-oriented therapy, ophthalmic nanoemulsions warrant more research. Full article
(This article belongs to the Section Surface Sciences and Technology)
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14 pages, 2116 KB  
Review
Filler Migration after Facial Injection—A Narrative Review
by Uwe Wollina and Alberto Goldman
Cosmetics 2023, 10(4), 115; https://doi.org/10.3390/cosmetics10040115 - 17 Aug 2023
Cited by 11 | Viewed by 41388
Abstract
Background: The injection of dermal fillers for facial esthetics has become a very popular procedure. Although usually safe in the hands of the experienced user, filler injections may bear a risk of unwanted side effects. Material and Methods: This is a narrative review [...] Read more.
Background: The injection of dermal fillers for facial esthetics has become a very popular procedure. Although usually safe in the hands of the experienced user, filler injections may bear a risk of unwanted side effects. Material and Methods: This is a narrative review of dermal filler migration after facial injections. We performed research on the literature on Pubmed and Google Scholar. Inclusion criteria were observational studies, case reports, and clinical trials which investigated the association of facial filler injections to filler migration. Animal studies have not been considered. Intravascular injections were excluded. Results: We identified 28 reports that met the inclusion criteria. The age range of affected patients was 21 to 86 years (mean ± standard deviation: 47 ± 14.8 years). Women were 25 times more reported than males. Hyaluronic acid and polyalkylimide were the most commonly encountered filler substances. Injections into the nose, lips, nasolabial folds, and forehead (including glabella) are more often reported for filler migration than injections into the cheeks. Tear-trough correction bears a risk for orbital migration. The delay from injection to presentation of filler migration was highly variable. Very late filler migration was more commonly seen with permanent fillers than non-permanent products. Conclusions: Filler migration distant from the injection site can occur even several years after the primary treatment. All filler types can be involved. Permanent fillers bear a higher risk of very late filler migration. Migration of permanent fillers needs surgical treatment, while HA fillers respond to hyaluronidase injections. Detailed knowledge of facial anatomy, safer injection techniques, and filler qualities are preventive measures. Full article
(This article belongs to the Special Issue Feature Papers in Cosmetics in 2023)
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22 pages, 9657 KB  
Article
Brow and Eyelid Rejuvenation: Trends from the 100 Most Cited Articles over 30 Years
by Doga Kuruoglu, Cristina A. Salinas, Daniel S. Kirk, Chin-Ho Wong and Basel A. Sharaf
Medicina 2023, 59(2), 230; https://doi.org/10.3390/medicina59020230 - 26 Jan 2023
Cited by 9 | Viewed by 6177
Abstract
Background and Objective: Various periorbital rejuvenation techniques have been introduced over the last 3 decades. This study highlights important milestones in the evolution of periorbital rejuvenation surgery by identifying the 100 most-cited articles in this field. Material and Methods: The Web of [...] Read more.
Background and Objective: Various periorbital rejuvenation techniques have been introduced over the last 3 decades. This study highlights important milestones in the evolution of periorbital rejuvenation surgery by identifying the 100 most-cited articles in this field. Material and Methods: The Web of Science citation index was used to identify the 100 most-cited articles concerning periorbital rejuvenation. Articles published in English from January 1989–April 2020 describing periorbital rejuvenation-related surgical techniques, facial aging, and anatomy were included. The terms “lower blepharoplasty”, “upper blepharoplasty”, “browlift”, “browplasty”, “endobrow lift”, “endoscopic brow”, “Foreheadplasty”, “lower eyelid anatomy”, “upper eyelid anatomy”, “forehead lift”, “eyelid rejuvenation”, “canthopexy”, “canthoplasty”, “eyelid fat pad”, “orbital fat pad”, “tear trough”, and “eyelid bags” were entered into the citation search. Web of Science Core Collection was the database used for the search. A manual review of the initial 159 studies was performed. Articles describing reconstructive or non-invasive techniques, injectable fillers, lasers, and neurotoxins were excluded. Of the 100 most-cited articles, the publication year, specialty journal, the corresponding author’s primary specialty, the focus of the article, the corresponding author’s country of residence, the type of study, and the level of evidence were analyzed. Results: The mean number of citations per article was 75 ± 42. There were more articles published from 1989–1999 (n = 53) than later decades. Most articles originated from the USA (n = 82) and were published in plastic surgery journals (n = 81). Plastic surgery was the primary specialty of the corresponding authors (n = 71), followed by oculoplastic surgery (n = 22). Most articles (n = 69) reported on surgical techniques. Of the clinical studies (n = 69), 45 (79%) provided level IV evidence. Conclusions: Of the 100 most-cited studies on periorbital rejuvenation, studies focusing on periorbital anatomy, aging, and surgical techniques comprised the most-cited publications. An anatomically based approach accounting for age-related changes in the periorbital structures is paramount in the field of contemporary periorbital rejuvenation. Full article
(This article belongs to the Special Issue New Trends in Craniomaxillofacial Surgery)
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13 pages, 4375 KB  
Article
Langmuir Trough Study of the Interactions of Tear Mimetic Eyedrop Formulation with Human Meibum Films
by Petar Eftimov, Norihiko Yokoi, Kazuhiro Tsuji, Nikola Peev and Georgi As. Georgiev
Appl. Sci. 2022, 12(23), 12095; https://doi.org/10.3390/app122312095 - 26 Nov 2022
Cited by 5 | Viewed by 2822
Abstract
Meibomian gland disease is associated with quantitative or qualitative deficiencies of meibum (MGS) that result in tear film instability. Thus, there is great demand for ophthalmic nanoemulsions that can replenish MGS and recover its performance at the air/tear surface. Rohto Dry Aid (RDA) [...] Read more.
Meibomian gland disease is associated with quantitative or qualitative deficiencies of meibum (MGS) that result in tear film instability. Thus, there is great demand for ophthalmic nanoemulsions that can replenish MGS and recover its performance at the air/tear surface. Rohto Dry Aid (RDA) utilizes TEARSHIELD TECHNOLOGYTM implementing a complex oil phase of non-polar and polar lipid-like molecules. Therefore, the interactions of RDA with MGS surface films deserve further study as they may provide valuable insights (i) into the mechanisms behind the nanoemulsion therapeutic action and (ii) for the design of novel ophthalmic formulations. Pseudobinary meibum/RDA films were formed at the air–water surface of the Langmuir trough. Surface pressure-area isocycles and stress relaxations were employed to probe the layer (i) reorganization upon cycling and (ii) dilatational elasticity, respectively. Film morphology was accessed by Brewster angle microscopy and the spreading properties of RDA-supplemented meibum were also probed. The diverse ingredients of the nanoemulsion oil phase complemented the non-polar and polar lipid constituents of the meibomian layers, which resulted in enhanced continuity of the MGS duplex film structure and facilitated the MGS spread and viscoelasticity. Nanoemulsions deserve further study as a potent tool for MGS-oriented therapy for dry eyes. Full article
(This article belongs to the Section Surface Sciences and Technology)
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15 pages, 1523 KB  
Systematic Review
Is the Treatment of the Tear Trough Deformity with Hyaluronic Acid Injections a Safe Procedure? A Systematic Review
by Salvatore D’Amato, Romolo Fragola, Pierfrancesco Bove, Giorgio Lo Giudice, Paolo Gennaro, Rita Vitagliano and Samuel Staglianò
Appl. Sci. 2021, 11(23), 11489; https://doi.org/10.3390/app112311489 - 3 Dec 2021
Cited by 5 | Viewed by 11851
Abstract
Among the various therapeutic options for the treatment of tear trough deformities, the use of hyaluronic acid-based fillers has constantly been increasing. The aim of this research is to conduct a systematic review of the published literature related to the use of hyaluronic [...] Read more.
Among the various therapeutic options for the treatment of tear trough deformities, the use of hyaluronic acid-based fillers has constantly been increasing. The aim of this research is to conduct a systematic review of the published literature related to the use of hyaluronic acid-based dermal fillers for the treatment of tear trough deformities and possible related complications. A search of the published literature was conducted following the PRISMA guidelines, including PubMed, Cochrane Library, and Ovid databases. Text words and Medical Search Headings (MeSH terms) were used to identify nine articles included in our analysis. The most used filler was Restylane (Galderma). The injection technique was performed through the use of a cannula or, more frequently, with a needle, through the execution of boluses or retrograde release. The injection plane was predominantly the supra-periosteal layer. The most observed side effects were mild and included redness, edema, contour irregularities, bruising, and blue-gray dyschromia. The degree of patient satisfaction was high, with an optimal aesthetic result that was maintained for 6 to 12 months. Although the duration of treatment of tear trough deformities with HA fillers is not comparable to surgical treatment, this is a minimally invasive, safe procedure, quick to perform, and with a high degree of patient satisfaction. Full article
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19 pages, 10041 KB  
Article
Recent Activity and Kinematics of the Bounding Faults of the Catanzaro Trough (Central Calabria, Italy): New Morphotectonic, Geodetic and Seismological Data
by Claudia Pirrotta, Graziella Barberi, Giovanni Barreca, Fabio Brighenti, Francesco Carnemolla, Giorgio De Guidi, Carmelo Monaco, Fabrizio Pepe and Luciano Scarfì
Geosciences 2021, 11(10), 405; https://doi.org/10.3390/geosciences11100405 - 26 Sep 2021
Cited by 19 | Viewed by 4296
Abstract
A multidisciplinary work integrating structural, geodetic and seismological data was performed in the Catanzaro Trough (central Calabria, Italy) to define the seismotectonic setting of this area. The Catanzaro Trough is a structural depression transversal to the Calabrian Arc, lying in-between two longitudinal grabens: [...] Read more.
A multidisciplinary work integrating structural, geodetic and seismological data was performed in the Catanzaro Trough (central Calabria, Italy) to define the seismotectonic setting of this area. The Catanzaro Trough is a structural depression transversal to the Calabrian Arc, lying in-between two longitudinal grabens: the Crati Basin to the north and the Mesima Basin to the south. The investigated area experienced some of the strongest historical earthquakes of Italy, whose seismogenic sources are still not well defined. We investigated and mapped the major WSW–ENE to WNW–ESE trending normal-oblique Lamezia-Catanzaro Fault System, bounding to the north the Catanzaro Trough. Morphotectonic data reveal that some fault segments have recently been reactivated since they have displaced upper Pleistocene deposits showing typical geomorphic features associated with active normal fault scarps such as triangular and trapezoidal facets, and displaced alluvial fans. The analysis of instrumental seismicity indicates that some clusters of earthquakes have nucleated on the Lamezia-Catanzaro Fault System. In addition, focal mechanisms indicate the prevalence of left-lateral kinematics on E–W roughly oriented fault plains. GPS data confirm that slow left-lateral motion occurs along this fault system. Minor north-dipping normal faults were also mapped in the southern side of the Catanzaro Trough. They show eroded fault scarps along which weak seismic activity and negligible geodetic motion occur. Our study highlights that the Catanzaro Trough is a poliphased Plio-Quaternary extensional basin developed early as a half-graben in the frame of the tear-faulting occurring at the northern edge of the subducting Ionian slab. In this context, the strike-slip motion contributes to the longitudinal segmentation of the Calabrian Arc. In addition, the high number of seismic events evidenced by the instrumental seismicity, the macroseismic intensity distribution of the historical earthquakes and the scaling laws relating to earthquakes and seismogenic faults support the hypothesis that the Lamezia-Catanzaro Fault System may have been responsible for the historical earthquakes since it is capable of triggering earthquakes with magnitude up to 6.9. Full article
(This article belongs to the Special Issue Morphogenic Faulting: Current Practices and Future Challenges)
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12 pages, 3390 KB  
Article
Periorbital Hyperpigmentation—Dark Circles under the Eyes; Treatment Suggestions and Combining Procedures
by Alberto Goldman, Mohamad Goldust and Uwe Wollina
Cosmetics 2021, 8(2), 26; https://doi.org/10.3390/cosmetics8020026 - 26 Mar 2021
Cited by 14 | Viewed by 68282
Abstract
Periorbital hyperpigmentation (POH) is a frequent concern among both young and adult patients. The etiology is multifactorial with a genetic background. Prevalence is higher in darker skin types. It has been estimated as high as 30% in a recent Indian study. Females are [...] Read more.
Periorbital hyperpigmentation (POH) is a frequent concern among both young and adult patients. The etiology is multifactorial with a genetic background. Prevalence is higher in darker skin types. It has been estimated as high as 30% in a recent Indian study. Females are often more disappointed by POH than males. Treatment has to consider underlying pathologies and patients’ needs. We present our treatment algorithm for POH. In this study, 74 patients with POH, 64 females (86.5%) and 10 males (13.3%), were treated. Of these, 39 patients (53%) had a family history of POH. The age range of patients was 18−57 years (average: 36.1 years). In case of tear trough deformity, soft tissue augmentation was used by injection of hyaluronic acid gel, calcium hydroxylapatite, or autologous fat. Blepharoplasty with partial fat pad resection or repositioning via arcus marginalis release was used to correct severe orbital fat herniation and excess of the lower lid skin. Melanin hyperpigmentation of the skin was improved by sessions of Q-switched 1064 and 532 nm neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. Small vessels (capillaries and veins) were targeted by a 1064 nm long-pulsed Nd-YAG laser. Sessions of intense pulsed light (IPL) or CO2 fractional laser were employed to improve skin texture and fine lines. Topical hyaluronic acid-based formulations may be used as adjuvant self-treatment by patients. For pigmented and mixed-type POH, ultraviolet light protection is recommended as a maintenance treatment. By the use of various technologies, treatment can be individually tailored. Full article
(This article belongs to the Special Issue Aesthetic and Cosmetic Dermatology)
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10 pages, 3362 KB  
Article
Development of an In Vitro Blink Model for Ophthalmic Drug Delivery
by Chau-Minh Phan, Manish Shukla, Hendrik Walther, Miriam Heynen, David Suh and Lyndon Jones
Pharmaceutics 2021, 13(3), 300; https://doi.org/10.3390/pharmaceutics13030300 - 25 Feb 2021
Cited by 20 | Viewed by 4109
Abstract
Purpose: The purpose of this study was to develop an advanced in vitro blink model that can be used to examine the release of a wide variety of components (for example, topical ophthalmic drugs, comfort-inducing agents) from soft contact lenses. Methods: The model [...] Read more.
Purpose: The purpose of this study was to develop an advanced in vitro blink model that can be used to examine the release of a wide variety of components (for example, topical ophthalmic drugs, comfort-inducing agents) from soft contact lenses. Methods: The model was designed using computer-aided design software and printed using a stereolithography 3D printer. The eyelid and eyeball were synthesized from polyvinyl alcohol and silicone material, respectively. Simulated tear fluid was infused through tubing attached to the eyelid using a syringe pump. With each blink cycle, the eyelid slides and flexes across the eyeball to create an artificial tear film layer. The flow-through fluid was collected using a specialized trough. Two contact lenses, etafilcon A and senofilcon A, were incubated in 2 mL of a water-soluble red dye for 24 h and then placed on the eye model (n = 3). The release of the dye was measured over 24 h using a tear flow rate of 5 µL/min. Results: Approximately 25% of the fluid that flowed over the eye model was lost due to evaporation, nonspecific absorption, and residual dead volume. Senofilcon A absorbed more dye (47.6 ± 2.7 µL) than etafilcon A (22.3 ± 2.0 µL). For etafilcon A, the release of the dye followed a burst-plateau profile in the vial but was sustained in the eye model. For senofilcon A, the release of the dye was sustained in both the vial and the eye model, though more dye was released in the vial (p < 0.05). Overall, the release of the dye from the contact lenses was higher in the vial compared with the eye model (p < 0.05). Conclusion: The blink model developed in this study could be used to measure the release of topical ophthalmic drugs or comfort agents from contact lenses. Simulation of a blink mechanism, an artificial tear film, and nonspecific absorption in an eye model may provide better results than a simple, static vial incubation model. Full article
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15 pages, 4186 KB  
Article
Improving Stability of Tear Film Lipid Layer via Concerted Action of Two Drug Molecules: A Biophysical View
by Petar Eftimov, Agnieszka Olżyńska, Adéla Melcrová, Georgi As. Georgiev, Philippe Daull, Jean-Sebastien Garrigue and Lukasz Cwiklik
Int. J. Mol. Sci. 2020, 21(24), 9490; https://doi.org/10.3390/ijms21249490 - 14 Dec 2020
Cited by 12 | Viewed by 3183
Abstract
The tear film at the ocular surface is covered by a thin layer of lipids. This oily phase stabilizes the film by decreasing its surface tension and improving its viscoelastic properties. Clinically, destabilization and rupture of the tear film are related to dry [...] Read more.
The tear film at the ocular surface is covered by a thin layer of lipids. This oily phase stabilizes the film by decreasing its surface tension and improving its viscoelastic properties. Clinically, destabilization and rupture of the tear film are related to dry eye disease and are accompanied by changes in the quality and quantity of tear film lipids. In dry eye, eye drops containing oil-in-water emulsions are used for the supplementation of lipids and surface-active components to the tear film. We explore in detail the biophysical aspects of interactions of specific surface-active compounds, cetalkonium chloride and poloxamer 188, which are present in oil-in-water emulsions, with tear lipids. The aim is to better understand the macroscopically observed eye drops–tear film interactions by rationalizing them at the molecular level. To this end, we employ a multi-scale approach combining experiments on human meibomian lipid extracts, measurements using synthetic lipid films, and in silico molecular dynamics simulations. By combining these methods, we demonstrate that the studied compounds specifically interact with the tear lipid film enhancing its structure, surfactant properties, and elasticity. The observed effects are cooperative and can be further modulated by material packing at the tear–air interface. Full article
(This article belongs to the Section Molecular Pharmacology)
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11 pages, 1079 KB  
Article
Insights into Tear Film Stability from Babies and Young Adults: A Study of Human Meibum Lipid Conformation and Rheology
by Poonam Mudgil, Douglas Borchman and Aparna Ramasubramanian
Int. J. Mol. Sci. 2018, 19(11), 3502; https://doi.org/10.3390/ijms19113502 - 7 Nov 2018
Cited by 20 | Viewed by 3792
Abstract
Babies have the most stable tears and people with dry eye have the least stable tears. Meibum may contribute to tear film stability, so in this study, the hydrocarbon chain conformation and rheology of meibum from babies was studied for the first time. [...] Read more.
Babies have the most stable tears and people with dry eye have the least stable tears. Meibum may contribute to tear film stability, so in this study, the hydrocarbon chain conformation and rheology of meibum from babies was studied for the first time. Infrared spectroscopy was used to measure lipid phase transitions. Rheology was measured using Langmuir film technology. Meibum from 25 donors 1 to 13 years old was compared with meibum from 18 donors 13 to 25 years old. The phase transition temperature and lipid order (stiffness) increased with increasing age from 1 to 25 years. The increase in meibum lipid order from 1 to 25 years of age may contribute to the instability of the tear film with age and contribute to films with a higher reciprocal compressibility modulus that are not as compressible and not as viscoelastic. Changes in the lipid phase transition parameters of meibum lipid with dry eye are an exacerbation of the changes observed with age. The lower reciprocal compressibility moduli of meibum films from children and babies compared with meibum from adults reiterates higher stability in their films which spread better, resist deformation, and facilitates their ability to be quickly restored after blinking. Full article
(This article belongs to the Section Physical Chemistry and Chemical Physics)
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19 pages, 4089 KB  
Article
Surface Properties of Squalene/Meibum Films and NMR Confirmation of Squalene in Tears
by Slavyana Ivanova, Vesselin Tonchev, Norihiko Yokoi, Marta C. Yappert, Douglas Borchman and Georgi As. Georgiev
Int. J. Mol. Sci. 2015, 16(9), 21813-21831; https://doi.org/10.3390/ijms160921813 - 9 Sep 2015
Cited by 44 | Viewed by 7739
Abstract
Squalene (SQ) possesses a wide range of pharmacological activities (antioxidant, drug carrier, detoxifier, hydrating, emollient) that can be of benefit to the ocular surface. It can come in contact with human meibum (hMGS; the most abundant component of the tear film lipid layer) [...] Read more.
Squalene (SQ) possesses a wide range of pharmacological activities (antioxidant, drug carrier, detoxifier, hydrating, emollient) that can be of benefit to the ocular surface. It can come in contact with human meibum (hMGS; the most abundant component of the tear film lipid layer) as an endogenous tear lipid or from exogenous sources as eyelid sebum or pharmaceuticals. The aims of this study were to determine (i) if SQ is in tear lipids and (ii) its influence on the surface properties of hMGS films. Heteronuclear single quantum correlation NMR confirmed 7 mol % SQ in Schirmer’s strips extracts. The properties of SQ/hMGS pseudo-binary films at the air/water interface were studied with Langmuir surface balance, stress-relaxation dilatational rheology and Brewster angle microscopy. SQ does not possess surfactant properties. When mixed with hMGS squalene (i) localized over the layers’ thinner regions and (ii) did not affect the film pressure at high compression. Therefore, tear SQ is unlikely to instigate dry eye, and SQ can be used as a safe and “inert” ingredient in formulations to protect against dry eye. The layering of SQ over the thinner film regions in addition to its pharmacological properties could contribute to the protection of the ocular surface. Full article
(This article belongs to the Section Biochemistry)
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