Recent developments of temperature‐responsive polymers for ophthalmic applications

Abstract

Blindness is one of the most feared disabilities. From cataracts and glaucoma to age-related macular degeneration and retinal vascular diseases, ocular diseases have adverse impacts on patients and pose a huge burden to the healthcare system. The World Health Organization estimates that out of 2.2 billion people with visual impairment, almost half of the cases can be preventedor has yet to be addressed. This presents an urgent clinical and societal need to be met. Temperature-sensitive hydrogels are one of the most biocompatible materials, which can be applied into the eye. By exploiting physiological temperature as a stimulus for in situ gel formation, control of the mechanical properties, rate of drug release, and biomechanical interactions can be tuned.They are very versatile and have immense potential in ocular applications by acting as vitreous substitutes in retinal surgery or topical eye drops and lenses for ocular discomfort and inflammation. In this article, we provide a review of the recent developments in temperature-responsive polymers in ophthalmic therapy in the past 5 years including retinal detachment, retinal vascular diseases, dry eyes, cataracts, age-related macular degeneration, and glaucoma.

Poly(2-alkyl-2-oxazoline)-Based Copolymer Library with a Thermoresponsive Behavior in Dodecane

“…The hydrophilicity and wettability of a polymer are crucial as they play a key role in numerous applications, particularly in the biomedical sector . While extremely hydrophilic polymers possess strong hydration layer and are useful for protection against undesirable interactions with blood proteins in vivo, hydrophobic polymers are also very valuable as coatings, engineering plastics, and adhesives and are beneficial in ophthalmic applications. − Therefore, the syntheses of both hydrophilic and hydrophobic polymers are necessary, and having the ability tune their wettability is a further advantage.…”

Applications of Degradable Hydrogels in Novel Approaches to Disease Treatment and New Modes of Drug Delivery

“…The anterior segment consists of the cornea, conjunctiva, iris, aqueous humor, ciliary body, and lens, and the posterior segment consists of the choroid, sclera, and retinal pigment epithelium [73]. Eye diseases are increasingly causing visual impairment and blindness around the world, and common eye diseases include dry eye, glaucoma, age-related macular degeneration, and retinal diseases [74,75]. Most of these diseases are treated with drugs that have low bioavailability and require frequent administration.…”

Applications and Recent Developments of Hydrogels in Ophthalmology

“…30 When the precursor solution of a thermosensitive hydrogel comes into contact with the ocular surface, a sol−gel change can occur due to reaching the gelation temperature, which can achieve in situ gelation and prolong the retention time to improve the ocular bioavailability of the drug. 31 (2) pH-sensitive hydrogels can undergo sol−gel phase transition in environments with different pH values. 32 The gel−sol phase transition is caused by the change in the ionization state of weakly acidic or weakly basic groups in polyelectrolytes despite the change in pH.…”

“…When the sol–gel transition occurs, the critical temperature is called the lower critical solution temperature (LCST), and when the gel–sol transition occurs, the critical temperature is called the upper critical solution temperature (UCST) . When the precursor solution of a thermosensitive hydrogel comes into contact with the ocular surface, a sol–gel change can occur due to reaching the gelation temperature, which can achieve in situ gelation and prolong the retention time to improve the ocular bioavailability of the drug . (2) pH-sensitive hydrogels can undergo sol–gel phase transition in environments with different pH values .…”