Masayoshi Abo

<p>Soft contact lenses (SCLs) change in shape along the cornea surface when worn because they are made of a soft material. The changes in shape of SCLs when worn were examined using three types of SCLs with different optical, intermediate, and bevel regions in this study. First, changes in SCL shape when worn were analyzed by the finite element method. Then, the effects of the changes in shape on SCL strength were examined by the ray-trace method. The results showed that 1) the shape of the SCLs changed by at least 0.25 D (diopter is a unit of measurement for lens strength) when worn; 2) the change in strength was small in SCLs having a shape that retains tear fluid in a small space in the intermediate region, as the optical region was displaced upward; and 3) bending deformation occurred in the bevel region due to tensile stress on the BC side and compressive stress on the FC side.</p>

Recently, a study to evaluate the optical properties of wearing CL has begun to improve the quality of vision. The soft contact lens (SCL) consists of an optics region, intermediate region and bevel, which improves the wearing feeling mainly. Because soft contact lens is composed of a soft material, it is deformed along the cornea when it is worn on the eye. In the present report, the shape of the commercial SCL is measured firstly by the light-section method. Then, the shape change of wearing SCL is calculated using a finite element method. At the end, influence on the lens diopter of the shape change of the SCL was investigated by CODE V. As a result, the focal length shortened by a shape change of SCL, and in the case of a lens of -6 Diopter, the lens changed than the diopter unit (0.25D) of production.