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Valdés-Arias D, Locatelli EVT, Sepulveda-Beltran PA, Mangwani-Mordani S, Navia JC, Galor A. Recent United States Developments in the Pharmacological Treatment of Dry Eye Disease. Drugs 2024; 84:549-563. [PMID: 38652355 PMCID: PMC11189955 DOI: 10.1007/s40265-024-02031-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2024] [Indexed: 04/25/2024]
Abstract
Dry eye disease (DED) can arise from a variety of factors, including inflammation, meibomian gland dysfunction (MGD), and neurosensory abnormalities. Individuals with DED may exhibit a range of clinical signs, including tear instability, reduced tear production, and epithelial disruption, that are driven by different pathophysiological contributors. Those affected often report a spectrum of pain and visual symptoms that can impact physical and mental aspects of health, placing an overall burden on an individual's well-being. This cumulative impact of DED on an individual's activities and on society underscores the importance of finding diverse and effective management strategies. Such management strategies necessitate an understanding of the underlying pathophysiological mechanisms that contribute to DED in the individual patient. Presently, the majority of approved therapies for DED address T cell-mediated inflammation, with their tolerability and effectiveness varying across different studies. However, there is an emergence of treatments that target additional aspects of the disease, including novel inflammatory pathways, abnormalities of the eyelid margin, and neuronal function. These developments may allow for a more nuanced and precise management strategy for DED. This review highlights the recent pharmacological advancements in DED therapy in the United States. It discusses the mechanisms of action of these new treatments, presents key findings from clinical trials, discusses their current stage of development, and explores their potential applicability to different sub-types of DED. By providing a comprehensive overview of products in development, this review aims to contribute valuable insights to the ongoing efforts in enhancing the therapeutic options available to individuals suffering from DED.
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Affiliation(s)
- David Valdés-Arias
- Bascom Palmer Eye Institute, University of Miami, 900 NW 17th St, Miami, FL, 33136, USA
| | - Elyana V T Locatelli
- Bascom Palmer Eye Institute, University of Miami, 900 NW 17th St, Miami, FL, 33136, USA
- Surgical Services, Miami Veterans Affairs Medical Center, 1201 Northwest 16th Street, Miami, FL, 33125, USA
| | | | | | - Juan Carlos Navia
- Bascom Palmer Eye Institute, University of Miami, 900 NW 17th St, Miami, FL, 33136, USA
| | - Anat Galor
- Bascom Palmer Eye Institute, University of Miami, 900 NW 17th St, Miami, FL, 33136, USA.
- Surgical Services, Miami Veterans Affairs Medical Center, 1201 Northwest 16th Street, Miami, FL, 33125, USA.
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2
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Zhuang-Yan A, Syed YY. Perfluorohexyloctane Ophthalmic Solution: A Review in Dry Eye Disease. Drugs 2024; 84:441-448. [PMID: 38554243 DOI: 10.1007/s40265-024-02016-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2024] [Indexed: 04/01/2024]
Abstract
Perfluorohexyloctane ophthalmic solution (Miebo®) is a single-entity, water-, steroid- and preservative-free, first-in-class semifluorinated alkane that is approved in the USA for the treatment of the signs and symptoms of dry eye disease (DED). DED is often linked with meibomian gland dysfunction (MGD), which causes an excessive evaporation of tears. Perfluorohexyloctane ophthalmic solution stabilizes the lipid layer of the tear film and inhibits tear evaporation by forming a monolayer at the air-liquid interface. In the phase III GOBI and MOJAVE trials in adults with DED associated with MGD, one drop of perfluorohexyloctane ophthalmic solution instilled in each eye four times daily over 8 weeks resulted in statistically significant and clinically meaningful improvements in the signs and symptoms of DED compared with hypotonic saline (0.6%). The agent was generally well tolerated, with most ocular adverse events being mild or moderate in severity. The efficacy and tolerability of perfluorohexyloctane ophthalmic solution was sustained for up to 52 weeks in an extension study (KALAHARI). As the first and currently the only prescription treatment approved in the USA directly addressing the pathophysiology of excessive tear evaporation, perfluorohexyloctane ophthalmic solution is a valuable emerging option for the management of DED.
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Affiliation(s)
- Amy Zhuang-Yan
- Springer Nature, Private Bag 65901, Mairangi Bay, Auckland, 0754, New Zealand.
| | - Yahiya Y Syed
- Springer Nature, Private Bag 65901, Mairangi Bay, Auckland, 0754, New Zealand
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3
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Roucaute E, Huertas-Bello M, Sabater AL. Novel treatments for dry eye syndrome. Curr Opin Pharmacol 2024; 75:102431. [PMID: 38277944 DOI: 10.1016/j.coph.2024.102431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 12/26/2023] [Accepted: 01/01/2024] [Indexed: 01/28/2024]
Abstract
Dry eye syndrome (DES) is a prevalent and multifactorial disease that leads to a self-perpetuating cycle of inflammation and damage to the ocular surface. This results in symptoms such as redness, burning, and blurred vision, which can negatively affect a patient's quality of life. While treatments are available to manage DES, they only temporarily relieve symptoms. Furthermore, long-term use of certain medications can cause harm to the ocular surface. Therefore, there is a need for safer and effective treatments for DES. This review highlights the latest advancements in DES therapy, providing valuable insights into ongoing efforts to improve patient outcomes.
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Affiliation(s)
- Esther Roucaute
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Marcela Huertas-Bello
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Alfonso L Sabater
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States.
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Wang YT, Yang PC, Zhang YF, Sun JF. Synthesis and clinical application of new drugs approved by FDA in 2023. Eur J Med Chem 2024; 265:116124. [PMID: 38183778 DOI: 10.1016/j.ejmech.2024.116124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 01/02/2024] [Accepted: 01/02/2024] [Indexed: 01/08/2024]
Abstract
In 2023, the U.S. Food and Drug Administration (FDA) granted approval to a total of 55 new drugs, comprising 29 new chemical entities (NCEs) and 25 new biological entities (NBEs). These drugs primarily focus on oncology, the central nervous system, anti-infection, hematology, cardiovascular, ophthalmology, immunomodulatory and other therapeutic areas. Out of the 55 drugs, 33 (60 %) underwent an accelerated review process and received approval, while 25 (45 %) were specifically approved for the treatment of rare diseases. The purpose of this review is to provide an overview of the clinical uses and production techniques of 29 newly FDA-approved NCEs in 2023. Our intention is to offer a comprehensive understanding of the synthetic approaches employed in the creation of these drug molecules, with the aim of inspiring the development of novel, efficient, and applicable synthetic methodologies.
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Affiliation(s)
- Ya-Tao Wang
- First People's Hospital of Shangqiu, Henan Province, Shangqiu, 476100, China.
| | - Peng-Cheng Yang
- Key Laboratory of Natural Medicines of the Changbai Mountain, Ministry of Education, Yanbian University, College of Pharmacy, Yanji, Jilin, 133002, China
| | - Yan-Feng Zhang
- Shangqiu Municipal Hospital, Henan Province, Shangqiu, 476100, China.
| | - Jin-Feng Sun
- Key Laboratory of Natural Medicines of the Changbai Mountain, Ministry of Education, Yanbian University, College of Pharmacy, Yanji, Jilin, 133002, China; Rega Institute for Medical Research, Medicinal Chemistry, KU Leuven, Herestraat 49-Box 1041, 3000, Leuven, Belgium.
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Saad A, Frings A. Influence of perfluorohexyloctane (Evotears®) on higher order aberrations. Int Ophthalmol 2023; 43:5025-5030. [PMID: 37864619 PMCID: PMC10724091 DOI: 10.1007/s10792-023-02905-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 09/27/2023] [Indexed: 10/23/2023]
Abstract
PURPOSE To prospectively assess the effect of regular application of perfluorohexyloctane (F6H8; Evotears®) on the tear film lipid layer, higher order aberrations (HOA) and the repeatability of measurements in healthy eyes. METHODS This prospective clinical study included 104 eyes treated with F6H8 four times daily for four weeks (group A) and 101 eyes that served as controls (group B). Measurements were performed with the WASCA aberrometer (Carl Zeiss Meditec GmbH, Jena, Germany). Main outcome measurement in addition to subjective refraction were the root mean square values of HOA measured before and after the intervention. RESULTS Regular use of F6H8 over a period of four weeks significantly increases HOA in healthy eyes (p < 0.05). In addition, the repeatability of measurement increases after the application of F6H8. CONCLUSION F6H8 may be a suitable treatment option to improve the accuracy of refractive assessment, although it increases HOA. Further studies are needed to confirm the effect on HOA and the repeatability of measurement.
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Affiliation(s)
- Amr Saad
- Department of Ophthalmology, University Hospital Duesseldorf, Heinrich-Heine University, Moorenstraße 5, 40225, Duesseldorf, Germany.
| | - Andreas Frings
- Department of Ophthalmology, University Hospital Duesseldorf, Heinrich-Heine University, Moorenstraße 5, 40225, Duesseldorf, Germany
- Augenheilkunde und Augenlaserzentrum PD Dr. med. Frings Nuremberg, Jena, Germany
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Kawahara A. Treatment of Dry Eye Disease (DED) in Asia: Strategies for Short Tear Film Breakup Time-Type DED. Pharmaceutics 2023; 15:2591. [PMID: 38004570 PMCID: PMC10674215 DOI: 10.3390/pharmaceutics15112591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/19/2023] [Accepted: 11/03/2023] [Indexed: 11/26/2023] Open
Abstract
Dry eye disease (DED) is a multifactorial disorder in which tear fluid homeostasis is lost, resulting in increased tear film osmolarity and ocular surface irritation. In Asia, the short tear film breakup time-type DED, which has become a global problem in recent years, is common. While the mainstay of DED treatment in the West is the suppression of inflammation, the first goal of treatment is the stabilization of the tear film in Asia. To date, artificial tears and steroid eye drops have been the main treatment for DED. However, artificial tears require frequent administration of eye drops and thus pose adherence problems, while steroids have problems with side-effects (cataracts, increased intraocular pressure). This review evaluates the new generation therapies in Asia based on what is known about them and demonstrates that they are more effective for DED than traditional therapies such as artificial tears and steroids. Based on considerations, it is proposed that the optimal treatment for the short tear film breakup time-type DED is the initial application of mucin-secretion-enhancing eye drops (long-acting diquafosol) and oral supplements; and if additional treatment is needed, cyclosporine eye drops and the adjunctive therapies presented in this review are added.
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Affiliation(s)
- Atsushi Kawahara
- Yoshida Eye Hospital, 2-31-8, Hondori, Hakodate 041-0851, Hokkaido, Japan
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Ballesteros-Sánchez A, De-Hita-Cantalejo C, Sánchez-González MC, Jansone-Langine Z, de Sotomayor MA, Culig J, Sánchez-González JM. Perfluorohexyloctane in dry eye disease: A systematic review of its efficacy and safety as a novel therapeutic agent. Ocul Surf 2023; 30:254-262. [PMID: 37813152 DOI: 10.1016/j.jtos.2023.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 10/01/2023] [Accepted: 10/02/2023] [Indexed: 10/11/2023]
Abstract
Perfluorohexyloctane (F6H8), a physically and chemically inert synthetic compound, has recently emerged as a promising candidate for the treatment of DED due to its unique properties. A systematic review that only include full-length randomized controlled studies (RCTs), reporting the effects of F6H8 in three databases, PubMed, Scopus and Web of Science, was performed according to the PRISMA statement. The search period was performed between June 1, 2023, and June 21, 2023. The Cochrane risk of bias tool was used to analyze the quality of the studies selected. A total of six RCTs were included in this systematic review. F6H8 tear substitutes treatment achieved a higher improvement than control group interventions in most of the reported variables. The mean differences between both groups were in favor of F6H8 and were as follow: eye dryness score (EDS) base on a visual analogue scale (VAS) of -6.12 ± 4.3 points, ocular surface disease index (OSDI) questionnaire score of -2.8 ± 2.3 points, lipid layer thickness (LLT) of 11.4 ± 10.4 μm, total corneal fluorescein staining (tCFS) of -0.8 ± 0.3 points and ocular treatment-emergent adverse events (TEAEs) of -0.66 ± 1.7. Tear film break-up time (TBUT) was the only variable in favor of control group with a mean of -0.5 ± 0.4 s. Patient satisfaction after F6H8 tear substitutes treatment was high. Therefore, F6H8 tear substitutes improve dry eye symptoms and signs with a satisfactory tolerability and could be recommended in patients with DED.
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Affiliation(s)
- Antonio Ballesteros-Sánchez
- Department of Physics of Condensed Matter, Optics Area, University of Seville, 41012 Seville, Spain; Department of Ophthalmology, Clínica Novovision, 30008 Murcia, Spain.
| | | | | | - Zane Jansone-Langine
- University of Latvia, Jelgavas Street 1, Riga, Latvia; The Dr. Solomatin Eye Center, Marijas Street 2, Riga, Latvia
| | | | - Josip Culig
- Department of Medicine and Clinical Pharmacology, University of Applied Health Sciences, Zagreb, Croatia
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Frutos-Rincón L, Luna C, Aleixandre-Carrera F, Velasco E, Diaz-Tahoces A, Meseguer V, Gallar J, Acosta MC. The Contribution of TRPA1 to Corneal Thermosensitivity and Blink Regulation in Young and Aged Mice. Int J Mol Sci 2023; 24:12620. [PMID: 37628800 PMCID: PMC10454529 DOI: 10.3390/ijms241612620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 07/31/2023] [Accepted: 08/04/2023] [Indexed: 08/27/2023] Open
Abstract
The role of TRPA1 in the thermosensitivity of the corneal cold thermoreceptor nerve endings was studied in young and aged mice. The contribution of the TRPA1-dependent activity to basal tearing and thermally-evoked blink was also explored. The corneal cold thermoreceptors' activity was recorded extracellularly in young (5-month-old) and aged (18-month-old) C57BL/6WT (WT) and TRPA1-/- knockout (TRPA1-KO) mice at basal temperature (34 °C) and during cooling (15 °C) and heating (45 °C) ramps. The blink response to cold and heat stimulation of the ocular surface and the basal tearing rate were also measured in young animals using orbicularis oculi muscle electromyography (OOemg) and phenol red threads, respectively. The background activity at 34 °C and the cooling- and heating-evoked responses of the cold thermoreceptors were similar in WT and TRPA1-KO animals, no matter the age. Similar to the aged WT mice, in the young and aged TRPA1-KO mice, most of the cold thermoreceptors presented low frequency background activity, a low cooling threshold, and a sluggish response to heating. The amplitude and duration of the OOemg signals correlated with the magnitude of the induced thermal change in the WT but not in the TRPA1-KO mice. The basal tearing was similar in the TRPA1-KO and WT mice. The electrophysiological data suggest that the TRPA1-dependent nerve activity, which declines with age, contributes to detecting the warming of the ocular surface and also to integrating the thermally-evoked reflex blink.
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Affiliation(s)
- Laura Frutos-Rincón
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| | - Carolina Luna
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| | - Fernando Aleixandre-Carrera
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| | - Enrique Velasco
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| | - Ariadna Diaz-Tahoces
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| | - Víctor Meseguer
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| | - Juana Gallar
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
- Instituto de Investigación Biomédica y Sanitaria de Alicante, 03010 Alicante, Spain
| | - M. Carmen Acosta
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
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Du YL, Peng X, Liu Y, Wang JS, Ye YF, Xu KK, Qu JY, Chen H, Xie HT, Zhang MC. Ductal Hyperkeratinization and Acinar Renewal Abnormality: New Concepts on Pathogenesis of Meibomian Gland Dysfunction. Curr Issues Mol Biol 2023; 45:1889-1901. [PMID: 36975492 PMCID: PMC10047716 DOI: 10.3390/cimb45030122] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/18/2023] [Accepted: 02/21/2023] [Indexed: 03/02/2023] Open
Abstract
Meibomian gland dysfunction (MGD) is a functional and morphological disorder of the meibomian glands which results in qualitative or quantitative alteration in meibum secretion and is the major cause of evaporative dry eye (EDE). EDE is often characterized by tear film instability, increased evaporation, hyperosmolarity, inflammation, and ocular surface disorder. The precise pathogenesis of MGD remains elusive. It has been widely considered that MGD develops as a result of ductal epithelial hyperkeratinization, which obstructs the meibomian orifice, halts meibum secretion, and causes secondary acinar atrophy and gland dropout. Abnormal self-renewal and differentiation of the acinar cells also play a significant role in MGD. This review summarizes the latest research findings regarding the possible pathogenesis of MGD and provides further treatment strategies for MGD-EDE patients.
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Affiliation(s)
- Ya-Li Du
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xi Peng
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yang Liu
- Department of Ophthalmology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Jia-Song Wang
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - You-Fan Ye
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Kang-Kang Xu
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Jing-Yu Qu
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Hua Chen
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Hua-Tao Xie
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Ming-Chang Zhang
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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Weng J, Fink MK, Sharma A. A Critical Appraisal of the Physicochemical Properties and Biological Effects of Artificial Tear Ingredients and Formulations. Int J Mol Sci 2023; 24:ijms24032758. [PMID: 36769079 PMCID: PMC9917348 DOI: 10.3390/ijms24032758] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 01/26/2023] [Accepted: 01/31/2023] [Indexed: 02/04/2023] Open
Abstract
Dry eye disease is among the most prevalent diseases affecting the ocular surface. Artificial tears remain the cornerstone therapy for its management. There are currently a wide variety of marketed artificial tears available to choose from. These artificial tears differ significantly in their composition and formulation. This article reviews the physicochemical and biological properties of artificial tear components and how these characteristics determine their use and efficacy in the management of dry eye. Furthermore, this article also discusses the various formulations of artificial tears such as macro and nanoemulsion and the type of preservatives present in them.
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Affiliation(s)
- Judy Weng
- Chapman University School of Pharmacy, Chapman University, Irvine, CA 92618, USA
| | - Michael K. Fink
- Department of Pathology, University of Colorado Anschutz Medical Campus, Denver, CO 80045, USA
| | - Ajay Sharma
- Chapman University School of Pharmacy, Chapman University, Irvine, CA 92618, USA
- Correspondence: ; Tel.: +1-714-516-5498
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11
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Luna C, Quirce S, Aracil-Marco A, Belmonte C, Gallar J, Acosta MC. Unilateral Corneal Insult Also Alters Sensory Nerve Activity in the Contralateral Eye. Front Med (Lausanne) 2021; 8:767967. [PMID: 34869482 PMCID: PMC8634144 DOI: 10.3389/fmed.2021.767967] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/11/2021] [Indexed: 01/21/2023] Open
Abstract
After the unilateral inflammation or nerve lesion of the ocular surface, the ipsilateral corneal sensory nerve activity is activated and sensitized, evoking ocular discomfort, irritation, and pain referred to the affected eye. Nonetheless, some patients with unilateral ocular inflammation, infection, or surgery also reported discomfort and pain in the contralateral eye. We explored the possibility that such altered sensations in the non-affected eye are due to the changes in their corneal sensory nerve activity in the contralateral, not directly affected eye. To test that hypothesis, we recorded the impulse activity of the corneal mechano- and polymodal nociceptor and cold thermoreceptor nerve terminals in both eyes of guinea pigs, subjected unilaterally to three different experimental conditions (UV-induced photokeratitis, microkeratome corneal surgery, and chronic tear deficiency caused by removal of the main lacrimal gland), and in eyes of naïve animals ex vivo. Overall, after unilateral eye damage, the corneal sensory nerve activity appeared to be also altered in the contralateral eye. Compared with the naïve guinea pigs, animals with unilateral UV-induced mild corneal inflammation, showed on both eyes an inhibition of the spontaneous and stimulus-evoked activity of cold thermoreceptors, and increased activity in nociceptors affecting both the ipsilateral and the contralateral eye. Unilateral microkeratome surgery affected the activity of nociceptors mostly, inducing sensitization in both eyes. The removal of the main lacrimal gland reduced tear volume and increased the cold thermoreceptor activity in both eyes. This is the first direct demonstration that unilateral corneal nerve lesion, especially ocular surface inflammation, functionally affects the activity of the different types of corneal sensory nerves in both the ipsilateral and contralateral eyes. The mechanisms underlying the contralateral affectation of sensory nerves remain to be determined, although available data support the involvement of neuroimmune interactions. The parallel alteration of nerve activity in contralateral eyes has two main implications: a) in the experimental design of both preclinical and clinical studies, where the contralateral eyes cannot be considered as a control; and, b) in the clinical practice, where clinicians must consider the convenience of treating both eyes of patients with unilateral ocular conditions to avoid pain and secondary undesirable effects in the fellow eye.
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Affiliation(s)
- Carolina Luna
- Instituto de Neurociencias, Universidad Miguel Hernández-CSIC, San Juan de Alicante, Spain
| | - Susana Quirce
- Instituto de Neurociencias, Universidad Miguel Hernández-CSIC, San Juan de Alicante, Spain
| | - Adolfo Aracil-Marco
- Instituto de Neurociencias, Universidad Miguel Hernández-CSIC, San Juan de Alicante, Spain
| | - Carlos Belmonte
- Instituto de Neurociencias, Universidad Miguel Hernández-CSIC, San Juan de Alicante, Spain
| | - Juana Gallar
- Instituto de Neurociencias, Universidad Miguel Hernández-CSIC, San Juan de Alicante, Spain.,Instituto de Investigación Sanitaria y Biomédica de Alicante, San Juan de Alicante, Spain
| | - M Carmen Acosta
- Instituto de Neurociencias, Universidad Miguel Hernández-CSIC, San Juan de Alicante, Spain
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