Synthesis of Soft Polysiloxane-urea Elastomers for Intraocular Lens Application

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomedical Engineering

Background:

• Accommodating intraocular lenses (a-IOLs) require materials with optical properties similar to the human eye lens.
• Polysiloxanes offer potential for a-IOLs but often need modification to achieve desired refractive indices and mechanical properties.
• Polysiloxane-based urea (PSU) elastomers are being explored for their unique combination of flexibility and durability.

Purpose of the Study:

• To synthesize soft polysiloxane-based urea (PSU) elastomers for accommodating intraocular lens (a-IOL) applications.
• To tailor the refractive index and mechanical properties of PSU elastomers for optimal performance.
• To evaluate the transparency, mechanical stability, and biocompatibility of the synthesized PSU elastomers.

Main Methods:

• Aminopropyl-terminated polydimethylsiloxanes (PDMS) were prepared via ring-chain equilibration.
• Phenyl groups were incorporated via copolymerization to enhance refractive index.
• Transparency was measured using UV-Vis spectrophotometry; mechanical properties via stress-strain tests and hysteresis measurements; cytotoxicity via MTS assay.

Main Results:

• PSU elastomers with a refractive index matching a young human eye lens were synthesized.
• Transmittance >90% was observed up to a PDMS molecular weight of 18,000 g·mol⁻¹.
• Mechanical hysteresis decreased with increasing PDMS molecular weight, indicating improved stability; selected elastomers showed no in vitro cytotoxicity.

Conclusions:

• A viable synthesis route for soft, transparent, and non-cytotoxic PSU elastomers for a-IOLs was established.
• The developed elastomers possess a refractive index comparable to a young human eye lens.
• The study demonstrates the potential of these tailored PSU elastomers for advanced intraocular lens applications.