Investigation of shrinkage and cracking of ophthalmic lens coating by a cycle test of UV radiation and high humidity

This paper presents some ophthalmic lens coating failures such as shrinkage, cracking, and cracking with delamination caused by UV radiation, elevated temperature, and moisture. These phenomena are caused by: 1) interactions at the interface between the plastic substrate and the hard coating (HC), and 2) plastic deformation with stress and relaxation of the HC/substrate interface. This phenomenon leads to an understanding of the mechanical properties of ophthalmic lenses through a QUV test which is found to be a useful method in developing better ophthalmic lens systems. The coating failures were investigated by means of different analysis techniques including optical microscope, scanning electron microscope, atomic force microscope, thermo mechanical analysis, and dynamic secondary ion mass spectrometry.