Different lenses have different properties. The density varies, known as index of refraction, and the ABBE VALUES are different for the various materials. The ABBE VALUE is a number given to describe the amount of chromatic aberration of an ophthalmic lens material. Here is a list of ABBE VALUES. The higher the number, the less…

FACT – UVA & UVB RAYS ARE HARMFUL More and more people are aware of the dangers caused by the sun. Your eyes, as well as your skin are at risk every time you step outside. You can reduce the risks of damaging your eyes by wearing sunglasses. What does ultraviolet (UV) mean? Ultraviolet is…

All about anti–reflective coatings Anti-reflection coatings are made from extremely thin layers of different dielectric materials that are applied in a high vacuum onto both surfaces of the lens. The quality of the AR depends upon the number of layers applied to the lens. The early coatings had only a single layer of magnesium fluoride…

SLAB-OFF EXPLAINED On occasion we have patients who come in with a prescription showing a significant power difference between the right and left eyes. Sometimes this variance is rather significant, around four diopters, or less significant, at around two diopters. This condition is called anisometropia, and is often congenital but can also be caused by…

The Issue of Adaptation “These aren’t working for me.” This isn’t what we want to hear from our patients. Before you fit progressives, please consider the following variables and realize that adaptation issues are a challenge that every Optician faces. If working with a multifocal patient, is this their first multifocal, or are they transitioning…

Tints, Filters and Sunglasses Tinted lenses are worn for the sake of appearance, comfort (discomfort glare), vision (disability glare) and protection against UV exposure. Sunglasses typically reduce transmission to 15%-25% and can be even darker for very bright conditions such as snow. At least 8% transmission is required to drive a car safely. Wearing sunglasses…

By definition an ophthalmic prism is wedge-shaped lens of glass or plastic that is thicker at one edge (the base) than at its opposite edge (the apex). Prisms usually are prescribed to correct faulty eye-muscle imbalances in which both eyes do not act as a team. In these cases, the refractive doctor prescribes the proper…

SHAMIR LENS DESIGNS Creation – 19mm fitting height Freeform Optics – design resolution up to six times more accurate than standard cast PAL’s Previous technologies created semi-finished PAL’s which used ceramic molds (mechanical molds) Freeform Optics – patented software which bypasses the ceramic molds and creates digital molds (Glass Molds) which provide higher resolution. Analogy…

Traditional vs Freeform Surfacing Traditional lens making tools can work only on the backside of the lens. They cannot create aspheric shapes or the complex curves required for PALs (progressive addition lens). This is why the progressive channel of designs has traditionally been pre-molded by the manufacture on the front surface of the lens. Freeform…

The following are facts about SHAMIR Shamir was established in 1970 as an engineering firm and is now the largest lens designer in the world. In 2004 Shamir had cooperatively designed 7 of the 12 top selling progressive lenes Shamir designed the first free form lens the Definity six years ago. Shamir has trademark rights…