Defects in Ophthalmic Lenses (Spectacle Lenses) – Comprehensive Explanation

Defects in Ophthalmic Lenses Ophthalmic lenses can have various manufacturing and optical defects that impact their performance. These defects can arise due to material properties, production errors, or improper handling. Below is a detailed classification of defects found in spectacle lenses, including bubbles, striae, and other imperfections . 1. Optical Aberrations (Image-Related Defects) These defects affect how light passes through the lens, causing distortions or blurriness. a. Spherical Aberration Light rays passing through the edges of the lens focus at a different point than those passing through the center . Causes halos and glare around lights. More prominent in high-powered lenses . Solution: Aspheric lens design . b. Chromatic Aberration Different wavelengths of light focus at different points , causing color fringes around objects. More noticeable in high-index lenses with a low Abbe number . Solution: Using high Abbe value materials (e.g., CR-39) or achromatic lens designs . c. Coma Aberra…