Imaging protein deposits on contact lens materials

Area of Science:

• Ophthalmology
• Biomaterials Science
• Surface Chemistry

Background:

• Traditional methods for studying protein deposition on contact lenses involve removal, which can lead to inaccurate results.
• Understanding protein-film formation is crucial for contact lens comfort and safety.

Purpose of the Study:

• To investigate in situ imaging techniques for analyzing protein deposition on poly(2-hydroxyethyl methacrylate) (polyHEMA) and silicone hydrogel contact lenses.
• To compare protein deposition patterns across different contact lens materials without removal.

Main Methods:

• Six silicone hydrogel and five polyHEMA-based contact lens materials were analyzed using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM).
• Lenses were exposed to lysozyme or a mixture of lysozyme and albumin-conjugated gold spheres in an in vitro model.
• AFM examined lysozyme deposition at physiological concentrations, while SEM assessed mixed protein deposition.

Main Results:

• Surface topographies varied significantly among the tested lens materials.
• Silicone hydrogel lenses (galyfilcon A, balafilcon A) showed large protein aggregates, while others (lotrafilcon A, B) exhibited a more uniform monolayer.
• Polymer (polymacon) lenses accumulated more protein than silicone hydrogels, with significant aggregation.
• Lysozyme deposition patterns differed, with galyfilcon A showing aggregates and string-like formations.

Conclusions:

• In situ imaging provides a promising approach for characterizing protein deposits on contact lenses.
• Protein deposition patterns vary significantly between different silicone hydrogel contact lens materials.
• Material composition influences the extent and physical nature of protein deposition on contact lenses.