Abstract: The method of evaluating an optical defect in a transparent material includes irradiating the material with light to produce scattered light from the defect, rotating the material about a rotation axis passing through the defect, measuring scattered light intensity at a scattering angle (?s) to the rotation axis by means of a detector, determining the dependence of the measured scattered light intensity on rotation angle (?s) around the rotation axis and characterizing size and/or shape of the defect from that dependence. The apparatus for performing the method has a light source, a rotatable holder for the transparent material, a light sensitive receiving device and an imaging optical system for imaging scattered light from the material within a certain angular range on a detector surface of the receiving device.