Ocular Drug Delivery Systems Using Contact Lenses

SMILE-Derived Corneal Stromal Lenticule: Experimental Study as a Corneal Repair Material and Drug Carrier

PURPOSE

A detailed study of the physicochemical properties of SMILE-derived lenticules and evaluation of their drug delivery after loading with silver nanoparticles (AgNPs).

METHODS

The lenticules were decellularized and modified with crosslinking concentrations of 0.01 (0.01E/L), 0.05 (0.05E/L), and 0.25 (0.25E/L) mmol N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) per mg lenticule at 5:1 carbodiimide/N-hydroxysuccinimide (EDC/NHS) ratios. The degree of swelling, light transmittance, biomechanical properties, and stability of the non-crosslinked decellularized lenticules (DLs), 0.01E/L, 0.05E/L, and 0.25E/L were measured and characterized using Fourier transform infrared spectroscopy and transmission electron microscopy with non-crosslinked non-decellularized lenticules as controls. DLs, 0.01E/L, 0.05E/L, and 0.25E/L were soaked in AgNPs for 24 hours, and the concentration of the drug released was measured.

RESULTS

There was no significant difference in the degree of swelling between the groups (P > 0.05). The light transmittance of the lenticules did not change after decellularization and crosslinking and decreased after loading with AgNPs. Non-decellularized lenticules biodegraded within 108 to 120 hours, and the other groups biodegraded within 96 to 108 hours in vitro. The 0.01E/L had the highest tensile strength. The absorption peak intensity ratio of the amide I band and the amide II band decreased, and the arrangement of collagen fibers was more compact in crosslinked decellularized lenticules. The 0.01E/L had the highest cumulative drug release (3.4 ± 0.91 μg).

CONCLUSIONS

Crosslinking decellularization improved the biomechanical properties and resistance to water absorption of lenticules, increased covalent bonds between collagen fibers, and improved drug delivery. Crosslinked decellularized lenticules can be used as a new corneal patch material and drug delivery carrier for drug AgNPs.

Ocular drug delivery systems: glaucoma patient perceptions from a German university hospital eye clinic

PURPOSE

This study aimed to report on glaucoma patients' beliefs and illness perceptions and to investigate their opinion on ocular drug delivery devices (ODD).

METHODS

We performed a cross-sectional study in a large tertiary-referral outpatient glaucoma clinic, with 102 patients. Validated anonymized questionnaires were used. We investigated the awareness and acceptance regarding ODD (contact lenses (CLs), punctal plugs (PPs), subconjunctival implants, anterior chamber (AC) injections, and drug-emitting stents) and looked at factors that could influence a patient's decision for having an ODD.

RESULTS

Sixty-three patients (61.8%) confirmed they would rather have ODD than keep their eye-drops (38.2%). The most important factors influencing their decision were effectiveness and long-lasting effect. A large proportion of patients reported a preference for CLs (48.0%), PPs (52.9%), or drug-emitting stents (44.1%). When comparing patients who preferred ODD (group-1) versus eye-drops (group-2), significantly more patients in group-1 were worried (p < 0.001) or felt disrupted (p < 0.001) by their use of eye-drops. A significantly greater share of patients in group-1 showed acceptance towards CLs (60.3% vs. 38.5%; p = 0.032), AC injections (38.1% vs. 12.8%, p = 0.006), or drug-emitting stents (54% vs. 28.2%, p = 0.023), whilst there were no significant differences regarding the acceptance of PPs (p = 0.363) or subconjunctival implants (p = 0.058).

CONCLUSION

ODD for the treatment of glaucoma were broadly deemed acceptable by patients in this study. Effectiveness and long-lasting effect were the most important factors for a decision towards having an ODD. The majority of patients who preferred an ODD felt severely affected by their disease and were negatively influenced by their glaucoma medication intake.

Overview of processed excipients in ocular drug delivery: Opportunities so far and bottlenecks

Ocular drug delivery presents a unique set of challenges owing to the complex anatomy and physiology of the eye. Processed excipients have emerged as crucial components in overcoming these challenges and improving the efficacy and safety of ocular drug delivery systems. This comprehensive overview examines the opportunities that processed excipients offer in enhancing drug delivery to the eye. By analyzing the current landscape, this review highlights the successful applications of processed excipients, such as micro- and nano-formulations, sustained-release systems, and targeted delivery strategies. Furthermore, this article delves into the bottlenecks that have impeded the widespread adoption of these excipients, including formulation stability, biocompatibility, regulatory constraints, and cost-effectiveness. Through a critical evaluation of existing research and industry practices, this review aims to provide insights into the potential avenues for innovation and development in ocular drug delivery, with a focus on addressing the existing challenges associated with processed excipients. This synthesis contributes to a deeper understanding of the promising role of processed excipients in improving ocular drug delivery systems and encourages further research and development in this rapidly evolving field.

A Survey on Patients' Opinions of Alternative Drug Delivery Systems for the Treatment of Glaucoma in South-South Nigeria

PURPOSE

Despite the human ocular surface being easily accessible, ocular drug delivery can be challenging. When applied improperly, topical medications, the most popular first-line treatment used to treat glaucoma, can have a very brief contact time with the ocular surface and may not have the desired therapeutic impact. Drug delivery devices are gadgets that can address some of these problems. This study aims to determine patients' opinions on ocular drug delivery devices used in the treatment of primary open-angle glaucoma (POAG).

METHODS

A pretested interviewer-administered questionnaire was used in a cross-sectional study of 115 POAG patients recruited from outpatient clinics in two Nigerian tertiary health institutions. Participants were asked about their understanding and acceptance of five Ocular drug delivery systems (ODD), namely drug-emitting contact lenses (CL), punctual plugs, subconjunctival injections, intracameral implants, and trabecular meshwork micro-stents, for the treatment of POAG.

RESULTS

Sixty (52.2%) participants, whose average age was 50 ± 9.8 years, were men. Self-pay was used for eye health treatments by 65% of participants. Of the participants, 68.7% admitted to using eye drops on their own. 57% of people were said to take their glaucoma medications consistently. CL and subconjunctival implants were seen to be most acceptable according to 39% and 30% of participants, respectively. Major factors determining the acceptability of ODD for POAG treatment were observed to be cost and effectiveness.

CONCLUSION

Patients in our cohort who are being treated for POAG have a fairly positive attitude towards ODD. The prospective use of these devices for POAG treatment in Nigeria will depend on their efficacy and cost, as well as how ophthalmologists will weigh ODD options.

Targeting Ocular Drug Delivery: An Examination of Local Anatomy and Current Approaches

Ocular drug delivery remains the focus of much modern research. Primary routes of administration include the surface, the intravitreal space, the subretinal space, and the subconjunctival space, each with its own series of unique challenges, limitations, and advantages. Each of these approaches requires careful consideration of the local anatomy, physical barriers, and key cells as well as the interface between the anatomy and the drug or drug system being delivered. While least invasive, the topical route poses a challenge with the many physical barriers that prevent drug penetration into the eye; while injection into the intravitreal, subretinal, and subconjunctival spaces are direct and targeted but limited due to the many internal clearance mechanisms and potential for damage to the eye. Polymeric-based, sustained-release drug delivery systems have been identified as a potential solution to many of these challenges; however, the design and successful implementation of a sustained-release system that is well-tolerated, bioactive, biocompatible, and degradable remains, in many cases, only in the early stages. The drugs and biomaterials in question also require special attention as small chemical changes could result in vastly different outcomes. This paper explores the anatomy and key cells of these four primary drug delivery routes as well as the interface between drug and drug delivery systems and the anatomy, reviewing the recent developments and current state of research in each area. Finally, this paper also examines the frequently used drugs and biomaterials found in ocular drug delivery and summarizes the primary interactions observed.

Soft Contact Lenses as Drug Delivery Systems: A Review

This review describes the role of contact lenses as an innovative drug delivery system in treating eye diseases. Current ophthalmic drug delivery systems are inadequate, particularly eye drops, which allow about 95% of the active substance to be lost through tear drainage. According to the literature, many interdisciplinary studies have been carried out on the ability of contact lenses to increase the penetration of topical therapeutic agents. Contact lenses limit drug loss by releasing the medicine into two layers of tears on either side of the contact lens, eventually extending the time of contact with the ocular surface. Thanks to weighted soft contact lenses, a continuous release of the drug over an extended period is possible. This article reviewed the various techniques to deliver medications through contact lenses, examining their advantages and disadvantages. In addition, the potential of drug delivery systems based on contact lenses has been extensively studied.

Emerging Trends in Nanomedicine for Improving Ocular Drug Delivery: Light-Responsive Nanoparticles, Mesoporous Silica Nanoparticles, and Contact Lenses

Vision is the most dominant of our senses, and it is crucial in every stage of our lives. Ocular diseases, regardless of whether they cause vision impairment or not, lead to personal and financial hardships. The anatomy and physiology of the eye strongly limit the efficacy of current ocular drug delivery strategies. Nanotechnology has been the ground for the development of powerful strategies in several fields, namely in medicine. This review highlights emerging nanotechnology-based solutions for improving ocular drug delivery and thus the bioavailability and efficacy of drugs. We focus our review on ambitious but promising approaches currently emerging to leverage the efficacy of nanoparticle-based systems in ocular therapy: (i) light-responsive nanoparticles, which enable spatiotemporal control of drug release; (ii) mesoporous silica nanoparticles, which offer high surface area-to-volume ratio, simple surface modification, good biocompatibility, and improved bioavailability; and (iii) contact lenses, which serve as a compliant method of nanoparticles use and as drug delivery systems for the treatment of ocular diseases.

Recent Research in Ocular Cystinosis: Drug Delivery Systems, Cysteamine Detection Methods and Future Perspectives

Cystinosis is a rare genetic disorder characterized by the accumulation of cystine crystals in different tissues and organs. Although renal damage prevails during initial stages, the deposition of cystine crystals in the cornea causes severe ocular manifestations. At present, cysteamine is the only topical effective treatment for ocular cystinosis. The lack of investment by the pharmaceutical industry, together with the limited stability of cysteamine, make it available only as two marketed presentations (Cystaran® and Cystadrops®) and as compounding formulations prepared in pharmacy departments. Even so, new drug delivery systems (DDSs) need to be developed, allowing more comfortable dosage schedules that favor patient adherence. In the last decades, different research groups have focused on the development of hydrogels, nanowafers and contact lenses, allowing a sustained cysteamine release. In parallel, different determination methods and strategies to increase the stability of the formulations have also been developed. This comprehensive review aims to compile all the challenges and advances related to new cysteamine DDSs, analytical determination methods, and possible future therapeutic alternatives for treating cystinosis.