Quantitative Assessment of Ophthalmic Viscosurgical Devices on Visibility, Spreadability, and Durability as Corneal Wetting Agents for the Wet Shell Technique

Multifunctional natamycin modified chondroitin sulfate eye drops with anti-inflammatory, antifungal and tissue repair functions possess therapeutic effects on fungal keratitis in mice

Fungal keratitis (FK) is recognized as a stubborn ocular condition, caused by intense fungal invasiveness and heightened immune reaction. The glycosaminoglycan chondroitin sulfate exhibits properties of immunomodulation and tissue regeneration. In prior investigations, oxidized chondroitin sulfate (OCS) ameliorated the prognosis of FK in murine models. To further improve the curative efficacy, we used the antifungal drug natamycin to functionalize OCS and prepared oxidized chondroitin sulfate-natamycin (ON) eye drops. The structure of ON was characterized by FTIR, UV-vis, and XPS, revealing that the amino group of natamycin combined with the aldehyde group in OCS through Schiff base reaction. Antifungal experiments revealed that ON inhibited fungal growth and disrupted the mycelium structure. ON exhibited exceptional biocompatibility and promoted the proliferation of corneal epithelial cells. Pharmacokinetic analysis indicated that ON enhanced drug utilization by extending the mean residence time in tears. In murine FK, ON treatment reduced the clinical score and corneal fungal load, restored corneal stroma conformation, and facilitated epithelial repair. ON effectively inhibited neutrophil infiltration and decreased the expression of TLR-4, LOX-1, IL-1β, and TNF-α. Our research demonstrated that ON eye drops achieved multifunctional treatment for FK, including inhibiting fungal growth, promoting corneal repair, enhancing drug bioavailability, and controlling inflammatory reactions.

Advances in Understanding the Mechanism of Ophthalmic Viscosurgical Device Retention in the Anterior Chamber or on the Corneal Surface during Ocular Surgery

Retention durability, especially in the eye, is one of the most important properties of ophthalmic viscosurgical devices (OVDs) during ocular surgery. However, the information on the physical properties of OVDs is insufficient to explain their retention durability. The purpose of this study is to clarify the mechanism of OVD retention to improve understanding of the behavior of OVDs during ocular surgery. To elucidate the mechanism of OVD retention, we have developed a new test method for measuring repulsive force. As a result, the maximum repulsive force of OVDs was positively and well correlated with the retention durability of investigated OVDs. Consequently, we demonstrated that the repulsive force could be used as an index of retention durability on the ocular surface and in the eye. We directly compared the intraocular retention durability of three OVDs (Shellgan, Viscoat, and Opegan-Hi) in ex vivo porcine eyes. Opegan-Hi was immediately removed from the anterior chamber, but Shellgan and Viscoat remained largely in the anterior chamber as determined by fluorescence imaging. These results showed that the intraocular retention behavior of OVDs was similar to their ocular surface behavior in our previous report, suggesting that retention durability is dependent on the OVD itself. The retention durability of Shellgan seemed to be higher than that of Viscoat, and the maximum repulsive force of Shellgan was 1.35-fold higher than that of Viscoat. Therefore, the repulsive force might be a useful index for assessing the difference in the retention durability between OVDs such as Shellgan and Viscoat.