All About Lens Prescriptions and Lens Options
Another resource is the section on ophthalmic lenses in wikipedia.
Sphere, Cylinder, and Axis
Transposition of Prescriptions
Prism by Decentration
Dispensing And Spectacle Lens Options
Focus on Technologies: Progressives
Fundamentals of Progressive Addition Lenses
Identifying Progressive Lenses
Lens Materials and their properties (Refractive Index, Specific Gravity, Abbe Value, Reflectance, Transmittance)
Comparison of Materials
Glass, CR-39, High Index , Polycarbonate, Trivex
Trivex vs. Polycarbonate
Focus on Technologies: Aspherics
Aspheric Lenses: Optics and Applications
Lens Thickness Equations and Estimations
Focus on Processing: Coatings
AR Coating *
Polarized Lenses - Color, Efficiency, and Use
DriveWear ®Lenses Polarization and Transitions (this goes to www.Drivewearlens.com site Younger Optics Drivewear site which requires Flash). Drivewear is the first polarized photochromic lens to darken behind the windshield of a car, allowing Drivewear to change from high contrast green/ yellow to copper to dark reddish brown (depending on lighting conditions) in order to enhance the driver’s vision. It is only available by custom fabrication, even with or without prescription.
*Anti-Refective Coatings (AR coatings)---The benefits of AR Coatings are reviewed on wikipedia (link listed below), but we have noticed some complaints from our patients over the years with AR coatings. These have involved cost, cleaning, and the fact that sometimes the coatings have peeled off the lenses. The main benefit of an AR coating is that it seems to make the lens disappear from the frame, while leaving the prescription, so that the lens bends the light as it should to improve your vision, while ridding the wearer of the awareness of the lens. When you look at or through a clear (untinted) lens, you are aware of the lens being there by light reflected off its surfaces. Even a lens that has surface finger prints, dust, dirt, and scratches, these defects of the lens surface may not be readily seen on an uncoated lens because they are generally absorbed into the reflection. So the main complaint that new wearers of AR coated lenses may have is noticing things on the lens that they didn't notice on an uncoated lens. And this brings about the problem of cleaning AR coated lenses. They take special care. In order to keep AR coated lenses from showing the finger prints, dust and dirt they must be kept cleaner than non-coated lenses. There are newer AR coatings that have special protective coatings over and under the AR coatings, that make the lenses scrach-resistant, resist dust and fingerprints, make lenses easier to keep clean and keep the AR coating from peeling off. AR coating laboratories make AR coatings available both with and without the premium features. In our office the standard AR coatings add $45.00 to the cost of a pair of lenses and the premium coatings are more, depending on their features. Vivex coating (by iCoat Company - link listed below) has most of the premium features for a cost of only $10.00 more than standard AR coating. Most durable premium coatings cost more.