Mechanically triggered solute uptake in soft contact lenses

Area of Science:

• Materials Science
• Biomedical Engineering
• Physical Chemistry

Background:

• Solute diffusion in soft contact lenses is influenced by molecular arrangement and water availability.
• Hyaluronan (HA), a key ophthalmic polysaccharide, uptake is critical for lens performance and drug delivery.
• The role of water states within hydrogels and their interaction with mechanical stimuli remains an area of investigation.

Purpose of the Study:

• To investigate the impact of low-frequency mechanical vibrations (200 Hz) on solute uptake in hydrated soft contact lenses.
• To determine the influence of loosely-bound water on mechanically enhanced solute transport.
• To evaluate the potential of mechanical vibrations as a method for improving solute delivery into contact lenses.

Main Methods:

• Differential scanning calorimetry (DSC) to characterize water states in hydrogel contact lenses.
• Scanning electron microscopy (SEM) to assess lens pore size.
• Solute uptake experiments involving hyaluronan immersion and vibration at 200 Hz.
• Analysis of bonding energies of loosely-bound water.

Main Results:

• A significant fraction of loosely-bound water was identified in the hydrogel material, persisting even after daily wear.
• Hyaluronan molecule size was smaller than the observed lens pore size.
• Negligible hyaluronan uptake occurred via simple immersion, but uptake significantly increased under 200 Hz mechanical vibrations.
• Mechanically triggered enhanced solute uptake is attributed to the release of interfacial loosely-bound water.

Conclusions:

• Mechanical vibrations at 200 Hz can significantly enhance hyaluronan uptake in soft contact lenses.
• The effectiveness of this method is dependent on the presence of interfacial loosely-bound water within the lens material.
• This finding provides experimental evidence for mechanically triggered solute uptake, with potential applications in contact lens technology and drug delivery.