Mechanical properties and hydration of 3D printed silicone-based contact lenses

Digital light processing - based vat Photopolymerization (DLP) offers numerous opportunities for the fabrication of customized hydrogel structures; however, material limitations remain a key challenge for contact-lens-scale applications. In this study, lenses were fabricated via DLP-based vat photopolymerization using hydrogel blends of (3-(Trimethoxysilyl) propyl methacrylate) (TMSPMA), 2-hydroxyethyl methacrylate (HEMA), and polyethylene glycol diacrylate (PEGDA). The influence of TMSPMA concentration on mechanical, thermal, hydration, and cytocompatibility characteristics was systematically investigated. Equilibrium water content, swelling kinetics, and gel fraction analyses revealed that increasing TMSPMA enhanced network density and stability but reduced hydration. Mechanical and thermal analyses (tensile, flexural, TGA) confirmed improved stiffness, dimensional precision, and thermal resistance at moderate TMSPMA levels. Cytotoxicity assessment using ARPE-19 cells demonstrated a concentration-dependent improvement in biocompatibility, where HPT and low-TMSPMA samples exhibited reduced viability (<50%), while higher TMSPMA formulation (THPT4) achieved ∼80% viability with dense live-cell fluorescence, approaching the control response. This enhancement is attributed to reduced residual monomer toxicity and improved interfacial stability at higher TMSPMA incorporation. Overall, the TMSPMA/HEMA/PEGDA silicone hydrogel system demonstrates compatibility with DLP-based 3D printing and enables the fabrication of silicon contact lenses with improved mechanical stability, dimensional fidelity, thermal robustness, optical transmittance, and acceptable cytocompatibility.