With useful updates on the 3rd edition the 4th edition has also been redesigned with smaller print and thinner paper making it substantially lighter in weight but with no less content! This text is a useful in practice reference guide, and a "must have" for all dispensing opticians and covers off all the essential elements of frame and lens dispensing. It is essentially split into two halves - the first half is largely the practical aspects of the job of a dispensing optician or experienced optical dispensing assistant - frame types, materials and selection; frame, lens and pupillary measurements; ordering and verification including clear explanation of the use of a manual focimeter (lens meter); very well illustrated sections on standard alignment, adjustment, repair and modification of all types of frame which makes a useful training / reference aid in practice. The second half of the book is of more concern to students aiming to become a qualified dispensing optician or optometrist and covers mathematical principles relating to ophthalmic lenses - curvature, thickness, prism, decentration - and lens design including segmented multifocals, progressive power and occupational lenses. Other topics include anisometropia, absorptive lenses, lens materials (including sports and safety eyewear) and how lenses are edged, plus 3 appendices on Standards, special frames and correcting vertical differential prismatic effect. As an aid to self study every chapter ends with a comprehensive proficiency test and the answers are to be found in the back of the book.