Chemical Structure and Optical Properties of Hydrophilic and Hydrophobic Intraocular Lenses

To compare the optical properties of hydrophilic and hydrophobic intraocular lenses (IOLs) containing UV-absorber and to determine their chemical composition. Optical properties of different foldable hydrophilic and hydrophobic as well as non-foldable hydrophobic polymethylmetacrylate (PMMA) IOLs were evaluated in three powers of 15, 22 and 25 diopters. Optical properties were measured using UV-VIS (UV-Visible) spectroscopy between wavelengths 200 and 800 nm and chemical structure characteristics were determined by ATR (attenuated total reflectance) spectroscopy. ATR spectroscopy revealed that foldable hydrophilic and hydrophobic IOLs and non-foldable hydrophobic IOLs were respectively composed of hydroxyethylmethacrylate, a copolymer of phenylethylacrylate and phenylethylmethacrylate, and PMMA (in accordance with manufacturer’s claim).Cut-off points of the lenses were found to be around 350-420 nm. Increasing the IOL power from 15 to 22 diopters did not significantly change the cut-off points of foldable hydrophobic IOLs, however a considerable cut-off shift to higher wavelengths was noted when power increased to 25 diopters. PMMA lenses showed a constant cut-off at 400 nm for all power values. The increase in power is associated with absorption of lower energy UV radiation and shift of cut-off points to higher wavelengths in hydrophobic IOLs but with no considerable effect on cut-off points in PMMA IOLs.