China 
Africa 
Explore chapters and articles related to this topic
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].
Lenstar LS900 vs EchoScan US-800: comparison between optical and ultrasound biometry with and without contact lenses and its relationship with other biometric parameters
Published in Expert Review of Medical Devices, 2023
Veronica Noya-Padin, Jacobo Garcia-Queiruga, Maria Iacubitchii, Maria J. Giraldez, Eva Yebra-Pimentel, Hugo Pena-Verdeal
A total of 51 participants (13 men and 38 women) with a mean age of 22.2 ± 2.25 years (range from 18 to 28 years) were randomly recruited among university students. Participants were included if they had an auto-refracted sphere of − 10.00 to + 4.00D, astigmatism up to − 3.00D, anterior chamber angle ≥ 30º and a compensated intraocular pressure (IOP) ≤ 20.85 mmHg [2,18,19]. Patients were excluded if they had ever been diagnosed with an ocular infection, trauma disorders, diseases at the time of the study (glaucoma, scleral or corneal anomalies, dry eye disease, meibomian gland dysfunction, etc.), undergone ocular surgery, diagnosed with systemic disorders that could affect the measurements (diabetes mellitus, rheumatoid arthritis, etc.), or had a history of hypersensitivity or allergy to anesthesia [2,10,20]. No participant was under any type of topical, systemic treatment or used artificial tears at the time of the study. All participants gave their written informed consent to be included in the study. The study protocol followed the tenets of the Declaration of Helsinki and was approved by the Ethics Committee of the university (Approval number: USC 04/2022).
Latanoprost uptake and release from commercial contact lenses
Published in Journal of Biomaterials Science, Polymer Edition, 2020
Ryan R. Horne, Joseph T. Rich, Matthew W. Bradley, William G. Pitt
To make a traceable stock of drug, the unlabeled latanoprost supply was spiked with a small amount of tritium-labeled latanoprost. This stock of tritium-labeled latanoprost with known concentration was used to generate calibration curves corresponding to the two types of wash solutions used to extract latanoprost from contact lenses. The first type of wash was n-propanol which extracted the loaded drug from contact lenses. This n-propanol wash was repeated until radioactivity was indistinguishable from background, which never was more than three washes. After combining the washes, the radioactive signal above background represented the amount of drug extracted from a lens. The second type of wash was in a solution of artificial tears, the formulation of which has been reported in previous studies [19]. The purpose of this wash was to simulate the chemical environment of tears on the surface of the eye. The experiment was limited in that the dynamic mechanical environment of the eye (blinking) was not simulated, nor was the continual replenishment of tears. However, this in vitro experiment provided a convenient method for comparing different lenses with respect to drug delivery into artificial tears.
The tear turnover and tear clearance tests – a review
Published in Expert Review of Medical Devices, 2018
Izabela K. Garaszczuk, Robert Montes Mico, D. Robert Iskander, Alejandro Cerviño Expósito
Studies suggest that corneal permeability to fluorescein decreases in dry eye subjects undergoing treatment with unpreserved artificial tears, as a result of improvement in corneal epithelial disease [74–76]. This effect might be counteracted by preservatives, which increases corneal permeability [75–77]. Also, the inherent autofluorescence of cornea has to be taken into account and subtracted from the measured corneal and tear film fluorescence when TTR is calculated. Corneal autofluorescence was shown to increase with age [78].