The following is a summary of the various lens options
*GLASS - glass lenses offer superior optics and the most
scratch resistance. However, the primary disadvantage of glass lenses
is the weight, which is generally twice that of plastic lenses.
Glass lenses are not as safe to wear as they break more easily than
other materials. There are some limitations in tinting glass lenses.
*PLASTIC - conventional plastic lenses are about one half
the weight of glass lenses and can be tinted to almost any color
and density. Plastic is more easily scratched than glass, but it
can have an optional scratch resistance coating applied to it. Plastic
is less breakable than glass and it also absorbs more of the harmful
*POLYCARBONATE - these lenses are the most impact resistant
lenses available and therefore are the lens of choice for children,
active people and industrial safety glasses. Polycarbonate lenses
are usually the lightest and most comfortable lenses, and offer
a more attractive appearance because they are substantially thinner
than plastic lenses. They absorb all the harmful ultraviolet light
and can be tinted to many colors. All polycarbonate lenses have
a standard scratch resistance coating.
*HI INDEX - these are special plastic lenses that bend light
differently so that stronger prescriptions are made thinner than
conventional materials, allowing for a more attractive lens. Since
high index plastic lenses are thinner, they are also lighter in
weight. They absorb all the harmful ultraviolet light and can be
tinted to any color. These lenses come with a standard scratch resistance
*SINGLE VISION LENSES - these lenses function as all purpose
glasses for people who have a normal focusing ability. People who
normally wear bifocals or trifocals can use single vision lenses
for distance or near vision (reading glasses).
*FLAT TOP BIFOCALS - these are the traditional bifocals
in which the bifocal prescription is visibly seen with a line in
the bottom portion of the lens. The top portion of the lens is for
distance vision and the lower bifocal portion is for near vision.
The width of the bifocal is available in various sizes.
*TRIFOCALS - these lenses consist of three separate prescriptions.
The additional lens in the middle portion provides clear vision
at arms length distance, the area that is usually blurry for bifocal
wearers after the age of 50.
*PROGRESSIVES (No-Line) - these lenses provide all the benefits
of bifocals, but add the feature of continuous clear vision at all
distances, including mid-range or arms length distance. Progressive
lenses provide a smooth transition between different viewing areas,
with no annoying image jumps or distracting lines. These lenses
have a cosmetic advantage in that they do not reveal that the wearer
has bifocals. Progressive lenses are becoming the lens of choice
for bifocal and trifocal wearers.
*ASPHERIC LENSES - these new lenses provide special visual
and cosmetic benefits for stronger prescriptions. They enhance the
clarity of vision in the periphery of strong lenses. They also provide
a more attractive lens by decreasing the "bulgy" appearance
and the magnification affect of strong farsighted lenses. People
with strong nearsighted and farsighted prescriptions benefit from
thinner, lighter weight glasses when their lenses are aspheric.
*OCCUPATIONAL LENSES - special occupational designs are
available to solve demanding visual requirements for those who wear
bifocals or trifocals. An example is a lens that has a bifocal prescription
in the top of the lens for people who do a lot of overhead work.
*COMPUTER GLASSES - there are a variety of lens options
for those who use computers. These include all the above mentioned
lens designs, as well as special filters, tints and anti-reflection
coatings that can increase visual comfort.
*SPORTS GLASSES - all sorts of special lens designs are
available for the special needs of sports enthusiasts. Polycarbonate
is usually the material of choice for active sports.
*STANDARD TINTS - these tints are numerous in types of color
and densities. They remain unchanged whether a person is indoors
or outdoors. Certain tints can be added to a lens at a later date
and some existing tints can be altered to change it's color density.
Standard tints are commonly used for decreasing glare from indoor
lighting, decreasing the intensity of car headlights at night and
also for sunglasses.
*PHOTOCHROMATIC TINTS - these are the tints that change
density when a person goes from indoors to outdoors. They usually
darken enough outside so that a person's glasses can serve as a
pair of sunglasses as well as their everyday glasses. An example
of the glass photochromatic tint is "Photogrey Extra"
and the plastic tint is "Transitions".
*POLARIZED SUN TINT - this type of sunglass tint is unique
in that it eliminates the intense and annoying reflected glare.
They are especially advantageous for drivers, fisherman, hunters
and all types of outdoor activities.
OPTIONAL LENS TREATMENTS
*SCRATCH RESISTANCE COATING - light weight plastic lenses
scratch more easily than glass lenses. A special coating can be
applied to plastic lenses to help protect them from normal scratching.
*UV PROTECTION - it is generally accepted that the ultraviolet
rays in sunlight pose a potential harm to the eyes. Special treatment
is available for plastic lenses that completely block hazardous
UV light. Lenses like polycarbonate and high index have built-in
*ANTI-REFLECTION COATINGS - these special coatings are much
like those used for fine camera lenses. They reduce the amount of
glare and reflections of spectacle lenses produced by computer screens,
fluorescent lights and night lights (especially car headlights).
Glare from lenses can cause eyestrain and eye fatigue, as well as
distracting double images of lights when driving at night. Therefore,
an anti-reflective coating can enhance a person's comfort and efficiency
at work and provide a safer drive at night. Another benefit of these
coatings is that they improve the appearance of your glasses by
removing the distracting reflections seen by others.
*ROLL AND POLISH - this is the process of grinding or "rolling"
off a portion of the lens edge to make the edge thinnner to improve
it's cosmetic appearance. Then the lens edge is polished to remove
the unwanted grinding marks. The lens edge can also be polished
without it being "rolled" to remove the dull appearance
of standard lens edges.