This guide is intended to help you make an educated decision when purchasing eyewear and eyewear related products.

When choosing an eyewear frame, there are two basic materials used, namely, plastic and metal.    For those people who are allergic to metal, either metal frames with PLASTIC temples, or plastic frames are the best choice.

The newest  in vogue eyewear are the "three-piecers".   Remember when choosing this frame that it is going to be ultralight.   But, the lenses are drilled and screws are inserted to mount the lenses to the three different pieces, that is, the bridge between the lenses and the two temples.    Screws tend to loosen up at times, so be aware that you might be revisiting your eyewear provider to have the screws tightened every so often.

Also available are metal frames made out of TITANIUM or STAINLESS STEEL.   The great advantage of these is that they will NOT corrode.    Wear them with confidence if you are allergic to brass or coated brass.

As for lenses, the thin and light are super if you have a prescription higher than about a - 2.75 or a + 2.75.  Less than that, there is no great weight or thinness advantage.    Lenses are either what are called CR39 or Polycarbonate or Hi-Index (the basic three materials).

CR39 is the usual plastic lenses that we have all been familiar with for the past 55 years.   Researched and developed and originally manufactured only by PPG (Pittsburgh Plate Glass), they have been the standard of the industry since the end of WW II.

Polycarbonate lenses have the advantage of not only being lightweight, but also being strong EVEN WITH a thin center.    It is not recommended that CR39 lenses be surfaced (have prescription ground into the back surface) thinner than 2.0 millimeters at the center.    Polycarbonate lenses are strong even with a center of 1.0 millimeter.   Now that is thin!!!!   Polycarbonate lenses are absolutely the lens of choice for those who are involved actively in rough sports.

Hmmmm, has anyone noticed that not much is ever said about GLASS lenses?    Glass is heavy, and even when tempered, it can shatter into a "million" pieces if it breaks.   No fun going to the ER to have bits of glass removed from your eyes.   'Bout the only people who really need glass lenses are those who do welding for a living.   Just a personal thought, but don't let that frighten you away from purchasing glass lenses if you feel that the optical clarity of glass is somehow better.

Speaking of CLARITY..........CR39 and glass lenses both get their optical clarity from being polished on the back side (once the prescription has been surfaced into the back surface).  Lenses such as polycarbonate or TRIVEX get their clarity from being COATED.    That is why you NEVER clean such coated lenses with any harsh chemicals.   NEVER use Acetone to clean a Poly or Trivex lens.   NEVER!!!!!!!!!!

As for other tints and coatings, plastic takes tints very well, even lenses precoated for scratch resistence.

Hope this is a help to all you savy people.  

LEONARD OPTICAL company wrote this Guide and is wholly responsible for its content.  Any errors or oversights are strictly our responsibility.