Functionalised polysiloxanes as injectable, in situ curable accommodating intraocular lenses

Area of Science:

• Biomaterials Science
• Ophthalmology
• Polymer Chemistry

Background:

• Age-related vision loss, specifically presbyopia, is often caused by the hardening of the natural eye lens, diminishing its ability to focus.
• Current intraocular lens (IOL) replacements are rigid and do not restore the eye's natural accommodative ability.
• Restoring accommodation is a key goal for advanced IOLs to improve visual function in aged individuals.

Purpose of the Study:

• To synthesize functionalized polysiloxane macromonomers for injectable, in situ curable accommodating intraocular lenses (A-IOLs).
• To develop a soft gel material capable of refilling the lens capsular bag and restoring the eye's focusing ability.
• To evaluate the mechanical properties, curing characteristics, and biocompatibility of the developed polysiloxane material for ophthalmic applications.

Main Methods:

• Polysiloxane prepolymers were synthesized using ring-opening polymerization (ROP) of cyclosiloxanes, controlled by end-group capping with hexaethyldisiloxane (HEDS).
• Prepolymers were converted to macromonomers via hydrosilylation with allyl methacrylate (AM) to introduce polymerizable groups.
• In situ curing was achieved using blue light irradiation with a photo-initiator, and properties were assessed using photo-rheology, ex vivo primate lens stretching, and in vivo rabbit biocompatibility studies.

Main Results:

• Injectable polysiloxane macromonomers were synthesized with controlled viscosity and modulus, suitable for lens refilling.
• The material cured rapidly (within 5 minutes) under blue light irradiation to form a soft polysiloxane gel.
• Ex vivo studies showed the gel-refilled lenses achieved over 60% of the natural lens's accommodation amplitude.
• In vivo studies in rabbits demonstrated good biocompatibility of the soft gels with ocular tissues.

Conclusions:

• The developed polysiloxane macromonomers possess the optical and mechanical properties mimicking a young natural lens.
• These materials are promising candidates for injectable, in situ curable A-IOLs, offering a potential solution for restoring accommodation via lens refilling.
• The study highlights the feasibility of using light-curable silicone-based materials for advanced ophthalmic applications.