LENS MATERIALS and LENS THICKNESS
Different lenses have different lens material options.
There are several factors that determine how thick your prescription lenses will be-
- The size of the frame.
- The power of the Rx.
- The PD. (Distance between your pupils)
- The lens material (index).
Minus Power Lenses are thin in the center and thicker on the edges. The larger the frame is, the thicker the lens edges will be. To get the thinnest result, select a frame in the right size for your face and don't go larger than you need to. For thinner lenses with high minus prescriptions opt for high index lens materials, 1.56, 1.60, or 1.67 OR 1.74.
Plus Power Lenses are the opposite, the lenses are thicker in the center and thinner on the edges. All of our plus power lenses are aspheric, which means that they are by design, thinner and flatter than non-aspheric lenses. Aspheric lenses reduce the unsightly "bulge" effect and look much nicer. It's important to note, that in certain types of frames like semi-rimless and rimless styles, plus power lenses need to have some thickness in order to be mounted into the frame properly. Our lenses are made to be as thin as possible.
Custom Surfaced Plus Power Lenses - The final thickness is based on your Rx, your PD, the frame size, and the lens material, the lenses will come out with a set thickness that cannot be changed but they will be thinner than stock lenses. A basic example would be a stock +4.00 aspheric poly lens. Custom surfaced to your frame with your PD will usually result in a much thinner lens. A custom surfaced polycarbonate lens will usually be thinner than a high index stock lens. This is why lens manufacturers don't offer 1.74 high stock index lenses in plus powers. This principle is the same no matter whether the lens is single vision or bifocal, or progressive.
CR39 Resin (Plastic) CR39 is an old school lens material that has stuck around because it's cheap. The lenses are thick, heavy, and prone to chipping. They are not very scratch resistant. They are not impact resistant. They do not effectively filter UV. We do not offer CR39.
Polycarbonate (Poly) - Lightweight, thin and impact resistance. Great eye protection and required for those 18 years or younger.
Trivex - Lighter than poly but slightly thicker.
1.56 Mid Index - Thin and light like Poly but not quite as impact resistant. Some products are only available in 1.56 like BlueTech.
1.6 High Index - 20% thinner than poly.
1.67 High Index - 30% thinner than poly.
1.74 High Index - The thinnest lenses. Available in minus powers only.
SPECIAL LENS MATERIALS - Blue Light Filters
SBF or Smart Blue Filter - A clear lens filter that absorbs UV and about 20% of HEV/Blue Light.
BZ or Blue Zero - A clear lens filter that absorbs UV and about 20% of HEV/Blue Light.
(These initials might follow the material like: 1.67 SBF, for example.)