An optical layer made from a light-permeable material includes a surface and an optical microstructure having a plurality of elevations. The elevations of the microstructure protrude from a reference plane, which is parallel to the surface. The elevations of the microstructure each have a flank section which adjoins the reference plane and forms a uniform angle with the reference plane. The uniform angle is in a range from about 10° to about 26° or in a range from about 13° to about 23° or in a range from about 15° to about 20°. The optical layer according to the invention makes it possible for a light fixture to achieve a high light output rate (LOR) at the same time to produce a preferred light distribution curve (LDC).