EYEWEAR

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 regemended 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 gepany wrote this Guide and is wholly responsible for
its content. Any errors or oversights are strictly our
responsibility.