Effect of phthalate absorption on the physical properties of ophthalmic hydrogels: A comparative study of ophthalmic hydrogel materials

Ophthalmic hydrogels are known for their hydrophilicity, which although beneficial for eye comfort, also predisposes them to absorbing external compounds, including potentially harmful phthalates. This study investigated the absorption of dimethyl phthalate and diethyl phthalate, plasticizers found in numerous consumer products by ophthalmic hydrogels. The results demonstrate differential absorption capacities between the two hydrogels, attributed to their distinct compositions. The interaction between hydrogels and phthalates is found to be predominantly physical, as evidenced by unchanged chemical structures post-absorption. Notably, phthalate absorption alters surface properties, including surface free energy and water content, while oxygen permeability remains unaffected. These findings underscore the complexity of hydrogel-phthalate interactions and the necessity of accounting for environmental pollutants in the design of ophthalmic materials. This research contributes to the development of safer, more environmentally resilient ophthalmic hydrogels, emphasizing the importance of further studies to mitigate the effects of contaminants like phthalates on contact lenses and other ophthalmic devices.