This report investigates the effect of the first few higher-order, non-singular stress terms and the coefficient of optical anisotropy on the shapes of the initial curves and the caustics in birefringent plates under Mode I and Mode II static loading conditions. For Mode I and Mode II loading conditions, Williams stress function is employed to generate various theoretical initial curves and caustics. Some experimentally obtained double caustics are compared to the theoretically generated double caustics. The agreement is found to be good as far as the shapes of caustics are concerned although it is not easy, if not impossible, to distinguish the effect of each higher-order terms.