Abstract: The invention discloses a bi-convex lens having aspheric surfaces, each of substantially identical curvature. The lens may be used in a stand magnifier which comprises a stand adapted to be supported on a surface and to which is attached or attachable such a magnifying lens. At least part of the stand and the lens is tiltable with respect to the surface in either direction from a position where the lens is parallel to the surface, preferably through an angle of up to 20.degree..

Abstract: A convex lens has a geometric axis, defined to be an axis passing through the lens at a central point normally to the general plane of the lens, spaced from its optical axis defined to be an axis passing through the lens between its focal points. The lens may be manufactured from a mould, at least one concave surface of which has a center point spaced from a deepest point, said mould having a feed point at an edge point substantially in a plane extending from said center point through said deepest point to the edge of the concave surface. A transparent plastics material may then be injected into the mould cavity through the feed point.