Effect of types of hydrophilic acrylic monomers in reducing glistenings of hydrophobic acrylic intraocular lenses

To reduce the glistenings in the hydrophobic acrylic intraocular lens (IOL) materials, various types of hydrophilic acrylic monomers of 2-hydroxyethyl acrylate (HEA), 2-hydroxypropyl acrylate (HPA), 4-hydroxybutyl acrylate (HBA), and 2-hydroxyethyl methacrylate (HEMA) were copolymerized with a hydrophobic acrylic monomer, 2-phenoxyethyl acrylate (POEA). In this process, the effect of the types and amounts of hydrophilic acrylic monomers on the physical properties, such as glistenings, equilibrium water content (EWC), refractive index, and glass transition temperature of the resulting hydrophobic acrylic IOL materials was investigated. As the amounts of hydrophilic acrylic monomers (HEA, HPA, HBA and HEMA) increased, glistenings in the IOL materials were significantly decreased in all monomers. At the same amount of the hydrophilic acrylic monomers, the IOL materials from HEA showed the least number of glistenings, but those from HBA exhibited the largest number of glistenings, resulting in a reduction of glistenings in the following order of HEA > HPA > HEMA > HBA. The EWCs of the IOL materials decreased in the order of HEA > HPA > HEMA > HBA with the same amount of hydrophilic monomers. From the above results, it can be seen that the greater the degree of hydrophilicity, such as the amounts and EWCs of the hydrophilic acrylic monomers, the greater the effect of glistening reduction of the resulting IOL materials.