Lens Materials and Lens Designs
Physicists, mathematicians, chemists and engineers are creating, patenting, and marketing new lens technology at a breathtaking pace. Here is an overview of the theories driving modern ophthalmic lens materials and the most useful lens materials and lens designs for our patients.
Traditional theories of light have described it a ray of light as it passes through an optical system to explain the lower order of aberrations called myopia, hyperopia, and astigmatism. However, up to 17% of all optical aberrations cannot be explained with this theory. A new theory of light called the wavefront theory of light is necessary to explain higher orders of aberrations (HOA) that make up 17% of the aberrations.
Progressive Lenses
An introduction to the evolution of progressive lens designs and probably more then you ever wanted to know about progressive lens optics.
The first progressive lens was made in 1959. The earliest progressives created about 4 Diopters of unwarranted peripheral distortion (called astigmatism) for every 1 Diopter of reading power. There was no difference between the design for the right versus the left eye.
Lens Coatings
Glass lenses do not require anti scratch coatings. All organic lenses ( polycarbonate, plastic, hi index, Trivex) require that anti scratch properties be applied during the casting manufacturing process or applied later and cured with heat or U.V. Anti scratch single vision, bifocal, and progressive lenses will be molded with anti scratch in the mold. A stock bifocal or single vision lens will then be anti scratch treated on both the front and rear surface. If the lens needs to be surfaced, the surfacing will always be surfaced on the back surface. The surfacing lab must then reapply the anti scratch coating on the back surface and cure it with heat or U.V.