Latanoprost uptake and release from commercial contact lenses

Smart Contact Lenses for Healthcare Monitoring and Therapy

The eye contains a wealth of physiological information and offers a suitable environment for noninvasive monitoring of diseases via smart contact lens sensors. Although extensive research efforts recently have been undertaken to develop smart contact lens sensors, they are still in an early stage of being utilized as an intelligent wearable sensing platform for monitoring various biophysical/chemical conditions. In this review, we provide a general introduction to smart contact lenses that have been developed for disease monitoring and therapy. First, different disease biomarkers available from the ocular environment are summarized, including both physical and chemical biomarkers, followed by the commonly used materials, manufacturing processes, and characteristics of contact lenses. Smart contact lenses for eye-drug delivery with advancing technologies to achieve more efficient treatments are then introduced as well as the latest developments for disease diagnosis. Finally, sensor communication technologies and smart contact lenses for antimicrobial and other emerging bioapplications are also discussed as well as the challenges and prospects of the future development of smart contact lenses.

Recent Advances of Ocular Drug Delivery Systems: Prominence of Ocular Implants for Chronic Eye Diseases

Chronic ocular diseases can seriously impact the eyes and could potentially result in blindness or serious vision loss. According to the most recent data from the WHO, there are more than 2 billion visually impaired people in the world. Therefore, it is pivotal to develop more sophisticated, long-acting drug delivery systems/devices to treat chronic eye conditions. This review covers several drug delivery nanocarriers that can control chronic eye disorders non-invasively. However, most of the developed nanocarriers are still in preclinical or clinical stages. Long-acting drug delivery systems, such as inserts and implants, constitute the majority of the clinically used methods for the treatment of chronic eye diseases due to their steady state release, persistent therapeutic activity, and ability to bypass most ocular barriers. However, implants are considered invasive drug delivery technologies, especially those that are nonbiodegradable. Furthermore, in vitro characterization approaches, although useful, are limited in mimicking or truly representing the in vivo environment. This review focuses on long-acting drug delivery systems (LADDS), particularly implantable drug delivery systems (IDDS), their formulation, methods of characterization, and clinical application for the treatment of eye diseases.

CLEAR - Contact lens technologies of the future

Contact lenses in the future will likely have functions other than correction of refractive error. Lenses designed to control the development of myopia are already commercially available. Contact lenses as drug delivery devices and powered through advancements in nanotechnology will open up further opportunities for unique uses of contact lenses. This review examines the use, or potential use, of contact lenses aside from their role to correct refractive error. Contact lenses can be used to detect systemic and ocular surface diseases, treat and manage various ocular conditions and as devices that can correct presbyopia, control the development of myopia or be used for augmented vision. There is also discussion of new developments in contact lens packaging and storage cases. The use of contact lenses as devices to detect systemic disease has mostly focussed on detecting changes to glucose levels in tears for monitoring diabetic control. Glucose can be detected using changes in colour, fluorescence or generation of electric signals by embedded sensors such as boronic acid, concanavalin A or glucose oxidase. Contact lenses that have gained regulatory approval can measure changes in intraocular pressure to monitor glaucoma by measuring small changes in corneal shape. Challenges include integrating sensors into contact lenses and detecting the signals generated. Various techniques are used to optimise uptake and release of the drugs to the ocular surface to treat diseases such as dry eye, glaucoma, infection and allergy. Contact lenses that either mechanically or electronically change their shape are being investigated for the management of presbyopia. Contact lenses that slow the development of myopia are based upon incorporating concentric rings of plus power, peripheral optical zone(s) with add power or non-monotonic variations in power. Various forms of these lenses have shown a reduction in myopia in clinical trials and are available in various markets.

In vitro anti-inflammatory potential of marine macromolecules cross-linked bio-composite scaffold on LPS stimulated RAW 264.7 macrophage cells for cartilage tissue engineering applications

Biomaterials serve as an integral component of tissue engineering. They are designed to provide architectural framework of native extracellular matrix so as to encourage cell growth and eventual tissue regeneration. Naturally occurring biopolymers as scaffolds offer options for cartilage tissue engineering due to anti-inflammatory, biocompatibility, biodegradability, low toxicity of degradation by-products and plasticity in processing into a variety of material formats. Here we studied in vitro anti-inflammatory potential of marine macromolecules cross-linked bio-composite scaffold composed of hydroxyapatite, alginate, chitosan and fucoidan named as HACF on LPS stimulated RAW 264.7 macrophage cells. The effects of HACF on the viability of RAW264.7 cells, nitrite level, intracellular ROS as well as the mRNA levels of NF-κB, iNOS, COX-2, TNF-α, IL-1β and IL-6 were examined in LPS induced RAW264.7 macrophage cells. The results revealed that HACF hydrogel scaffold exerts anti-inflammatory effect by inhibiting the production of ROS, suppress NF-kB translocation to the nucleus and thereby inhibiting the production of inflammatory mediators. Hence, our results confirm that HACF has a strong anti-oxidant capacity to inhibit inflammation associated gene expression by suppressing NF-kB signaling pathway. It clearly reveals the anti-oxidant and anti-inflammatory effect of HACF hydrogel scaffold on LPS induced RAW 264.7 cells.

In Vivo Efficacy of Contact Lens Drug-Delivery Systems in Glaucoma Management. A Systematic Review

Adherence is crucial in medical glaucoma therapy, although half of the patients skip eyedrops. In recent years alternative drug-delivery systems have been developed. One of the most promising seems the contact lens (CL). This systematic review aims to present the in vivo efficacy of different CL drug-delivery systems. A total of 126 studies were identified following a literature search adhering to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. After full-text evaluation, 19 studies about CL drug-delivery systems were included. To date, the following drug-delivery systems have been investigated in vivo: drug-soaked CL, CL with physical barriers (vitamin E), molecularly imprinted CL, CL with implants, and nanoparticle-loaded CL. Nanoparticle-loaded CL and CL with implants seem the most promising drug-delivery systems, although initial burst drug release and patient acceptance may limit their widespread use in current practice. Clinical trials are warranted to understand the role of CL as a drug-delivery system in improving glaucomatous patient care.

Therapeutic Ophthalmic Lenses: A Review

An increasing incidence of eye diseases has been registered in the last decades in developed countries due to the ageing of population, changes in lifestyle, environmental factors, and the presence of concomitant medical conditions. The increase of public awareness on ocular conditions leads to an early diagnosis and treatment, as well as an increased demand for more effective and minimally invasive solutions for the treatment of both the anterior and posterior segments of the eye. Despite being the most common route of ophthalmic drug administration, eye drops are associated with compliance issues, drug wastage by lacrimation, and low bioavailability due to the ocular barriers. In order to overcome these problems, the design of drug-eluting ophthalmic lenses constitutes a non-invasive and patient-friendly approach for the sustained drug delivery to the eye. Several examples of therapeutic contact lenses and intraocular lenses have been developed, by means of different strategies of drug loading, leading to promising results. This review aims to report the recent advances in the development of therapeutic ophthalmic lenses for the treatment and/or prophylaxis of eye pathologies (i.e., glaucoma, cataract, corneal diseases, or posterior segment diseases) and it gives an overview of the future perspectives and challenges in the field.

Soft Contact Lens with Embedded Microtubes for Sustained and Self-Adaptive Drug Delivery for Glaucoma Treatment

Because of the physiological and anatomical constraints of the eye, ophthalmic drug delivery is challenging. When applied topically, less than 1% of administered ophthalmic drugs reach the aqueous humor. The delivery of a drug within an efficient therapeutic concentration, to the required site of action, for an extended period of time, is complicated. Herein, a novel type of contact lens device, with embedded microtubes as drug containers, is reported. This device can provide a simple, noninvasive, extended drug release up to 45 days with higher bioavailability and lower risk for adverse effects. Another unique feature of the device is the release of drug triggered by stretching of the contact lens, indicating the possibility for achieving a self-adaptive drug release device for treating glaucoma patients.