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Development of Ophthalmic Formulations
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Paramita Sarkar, Martin Coffey, Mohannad Shawer
Signs and symptoms of dry eye include itchiness, redness, foreign body sensation, and grittiness. Most treatments alleviate the signs and symptoms of dry eye rather than treating the cause. The most prevalent therapy for dry eye syndrome has been the use of OTC artificial tear formulations. Most of these OTC medications offer to alleviate the temporary discomfort due to dry eye by bathing the ocular surface in an aqueous environment supplemented with demulcents that help to retain moisture. However, the ocular surface is designed such that topically applied drops are quickly drained from the surface. In order for the beneficial effects of topical demulcents to last long enough to provide relief to dry eye patients, the artificial tear formulations usually contain additional components to increase the duration of the demulcents on the surface of the eye. These generally include viscosity-enhancing and/or mucoadhesive polymers. Many studies/review articles [57] have documented the utility of polymers that show “mucoadhesion” in prolonging the residence time of small molecules on the surface of the eye and have also recognized the role of viscous formulations in doing the same. The precorneal residence time of artificial tear formulations has been shown to be greater for formulations that have greater viscosities [58,59]. However, if the viscosity of a formulation is too high, and the formulation does not shear-thin with the blink, then there could be a high degree of discomfort to the patients [60]. Therefore, an ideal vehicle would maintain appreciable viscosity at rest, shear-thin in a manner similar to normal tears, and interact with mucin in the presence of normal tear fluid ions to have good ocular retention and comfort [59,61,62]. Table 13.2 compares the physicochemical properties for various OTC products. A new approach to dry eye treatment is the inclusion of aqueous, polymeric, and lipid components in a single formulation to target multiple layers of the tear film. A comprehensive review of OTC dry eye products has been put together by Moshirfar et al. [63].
Formulation development, optimization, and in vitro assessment of thermoresponsive ophthalmic pluronic F127-chitosan in situ tacrolimus gel
Published in Journal of Biomaterials Science, Polymer Edition, 2021
Deepika Modi, Musarrat H. Warsi, Vaidehi Garg, Meenakshi Bhatia, Prashant Kesharwani, Gaurav K. Jain
Dry eye disease is a multifactorial disease of the tears and ocular surface associated with discomfort, disturbance in vision, and tear film instability. Its efficient management is necessary, which depends upon the presence of TCS on the eye surface for an extended time. The conventional TCS topical ocular drops used for dry eye treatment have various disadvantages. Thereupon, the use of a TCS in situ ocular gelling system could be advantageous for disease management. This study was designed with the objective to develop a temperature-triggered in situ gel of TCS. The central composite experimental design was used to optimize the concentration of PL and CS polymers. Developed optimized formulation F2 remains liquid at lower temperatures and undergoes rapid change from a solution to gel form at body temperature. The in situ gel was demonstrated to be nonirritant with good gelling capacity, drug content, sustained release, and mucoadhesive properties with a high precorneal residence. Consequently, it can be figured out as a propitious topical ocular delivery system for tacrolimus as in situ gel than as conventional eye drops. The present work would lead to the development of a patient-compliant formulation for treating dry eye syndrome.
Mobile touch screen device use and associations with musculoskeletal symptoms and visual health in a nationally representative sample of Singaporean adolescents
Published in Ergonomics, 2019
Siao Hui Toh, Pieter Coenen, Erin K. Howie, Swarup Mukherjee, David A. Mackey, Leon M. Straker
Similar to musculoskeletal symptoms, a greater amount of smartphone use was significantly associated with visual symptoms experienced during or after use of MTSDs and showed a clinically meaningful increase in risk of having visual symptoms. Visual symptoms reported included eye strain, tiredness of eyes and dry eyes. Prior research has shown that continuous computer use increased the risk of having visual symptoms, thought to be due to prolonged near vision work, impaired blink reflex and blue light emitted from screens (Gowrisankaran, Sheedy, and Albin 2015; Lurati 2018). Use of smartphone also involves near vision of the screen, which might thus explain its association with visual symptoms, especially when smartphone use was substantial and of longest bout length of use among all the devices. However, no association was found between tablet use and visual symptoms, which might again be due to the low tablet exposures in this sample.
Tear osmolarity is sensitive to exercise-induced fluid loss but is not associated with common hydration measures in a field setting
Published in Journal of Sports Sciences, 2018
Justin J. Holland, Michelle Ray, Christopher Irwin, Tina L. Skinner, Michael Leveritt, Ben Desbrow
An innovative method to assess hydration status in the field may lie in the measurement of tear osmolarity (Tosm) (Fortes et al., 2011; Sollanek et al., 2012). Various methods have been trialled to capture and analyse tear fluid, primarily for the diagnosis of dry eye disease. The most common method is the Schirmer test, which uses absorptive paper or glass capillary tubes to collect tear film for the diagnosis of dry-eye disease (Esmaeelpour, Cai, Watts, Boulton, & Murphy, 2008). Collection times, inadequate sample volume (≥1µL) and evaporation have the potential to impact Tosm. In combination, these variables may produce an intra-subject variability of Tosm to the degree of 9.5 ± 2.4% (Benjamin & Hill, 1983) when assessed by the typical freezing point and vapour pressure osmometry (Stahl, Willcox, & Stapleton, 2012). More importantly, the method in which tear film is collected and the use of laboratory osmometers is not practical in the field. Tosm as assessed by the TearLabTM system is a relatively new, non-invasive method of hydration assessment that requires only (50 nL) of tear fluid in comparison to traditional assessment which requires ≥1 µL. Unlike the traditional methods, the TearLabTM system can provide an output within 10 s of collection, reducing the potential for evaporation and contamination. Given the safety, speed, limited invasiveness and acceptable analytical variation (0.98%) of the TearLabTM system, it may prove ideal for practical field-based hydration assessment over absorptive paper and glass capillary tubes that may irritate and disturb the ocular surface.