Purpose:
Hydrophobic acrylic (HA) materials are currently the ‘gold standard’ material for intraocular lenses used in cataract surgery. However, hydrophobicity is a broad classification that may be defined based on surface and bulk material properties. The purpose of this study is to evaluate widely-available intraocular lenses (IOLs) for various material properties that define the hydrophobic nature of the material.
Methods:
Widely-available hydrophobic acrylic (HA) IOL materials were examined using Atomic Force Microscopy (AFM) in their dry and hydrated state. Advancing and receding contact angle of IOL surfaces were measured using a Rame-Hart goniometer and followed up to 30 days. The lenses were also subjected to various temperature cycling methods to study surface and bulk material opacification.
Results:
Surface roughness and surface morphology examinations showed significant differences in the hydrophobic nature of the IOL materials in their dry and hydrated state. Long-term dynamic contact angle measurements of IOL surfaces revealed information on surface remodeling. Average time for surface to reach equilibrium was found to be approximately 72 hours in all cases. Further, examination of equilibrium water content and temperature cycling studies revealed the susceptibility of the various materials to surface haze and opacification. Materials that showed dramatic changes to surface properties after hydration demonstrated surface haze and bulk material opacification.
Conclusions:
Examination of several HA intraocular lens materials demonstrated significant differences in their hydrophobic nature. While the hydrophobic IOLs appeared to have similar properties in the dry state, there were significant changes observed in the surface and bulk material upon hydration. Hydration to equilibrium and storage in physiological saline enhances the long-term stability of the surface, mitigating further remodeling based on the in-situ environment that may lead to haze or opacification.
Keywords: intraocular lens