This research discusses the permissible defects on all types of optical lenses and the production stages at which these defects may occur. The defects found on spherical optical surfaces include: Complete surface cleanliness. Bubbles or spots on the surface. Scratches around the lens perimeter. Edge chipping and breakage. These defects may occur during the manufacturing processes of optical components (lenses), including: Polishing – the final surface finishing process. Lens Cementing – the process of bonding lenses together. Engraving – the process of marking or engraving the lens surface. Defects are classified into more than ten grades. These grades are distributed according to the size, width, and depth of the defect, with each grade representing approximately 10% of the allowable tolerance. The number of permissible defects on optical components is calculated according to established standards, and it is preferable that such defects do not occur within the optical axis area. As for edge breakage or chipping, defects larger than 0.5 mm should be investigated to determine their cause during production. If these defects occur outside the effective optical area, they generally do not affect the performance of the lenses and, consequently, do not affect the performance of optical devices, including prescription eyeglasses. However, the appearance of bubbles anywhere within the lens is unacceptable regardless of their number, because bubbles act as refractive media for light rays during use and therefore negatively affect lens performance. For this reason, defects within the optical axis region (effective area) are strictly controlled, and this region is often referred to as the zero-defect zone or zero area. Figure: The figure illustrates some types of defects that may appear on spherical optical surfaces during or after the manufacturing process. . Prof. Mundhir Samin Shukr University of Al-Mustaqbal – The First and Leading Private University