a saline solution and covered by a

a saline solution and covered by a coverslip. The plate was placed under the objective of a microscope with the retinal side 5.0 up. A transparent film of square grids of 4.9 or 5.0 mm was placed 115 mm or 120 mm below the plate in a light path from a halogen lamp. An image of the square grids formed by the corneal lens was photographed under the microscope, and its size was measured (Fig. 2A). In order to see the edges of an image clearly, the density distribution of the photograph was measured by a photosensor (Fig. 14).