Lens Materials for Spectacles
Basic of choosing lenses?
Now I have decided what type of lenses I
would like, what lenses should I choose? CR39 or impact resistant
lenses? Do I need high index lenses?
The lenses to choose for your glasses
on 3 factors: most importantly, your prescription. Secondly,
frame style of the glasses (i.e. whether it is rimless, full
rim or semi-rimless) and finally the purpose of the glasses.
Some lenses are not suitable for Rimless glasses, for example
CR39, while polycarbonate or high index 1.67 lenses are perfect
choices for Rimless glasses.
If your prescription has high power, high index lenses or
ground lenses have to be used otherwise the lenses would be
too thick. If your prescription has a sphere that is more
than -3 diopter, we do not recommend CR39 stock lenses.
Now you don't have to worry about any of these when you order
glasses from our web site. With built-in optical dispensing
inteligence, Smart Lens Program will work out the best lenses
for you on your budget.
To make your online shopping experience as
easy as possible, we have developed lens packages that are
suitable for different prescriptions. Separate lens packages
have been developed for sunglasses as well as single vision,
bifocal, progressive and computer eyeglasses.
Why impact resistant lenses?
After you enter your prescription, the smart lens program
will present you a maximum of 3 lens packages that are suitable
for your prescription in the order of basic to advanced features.You
can choose a package according to your budget. The first package
is usually sufficient for your prescription. The lenses for
advanced packages are usually thinner, lighter and have better
cosmetic appearance. They are good options if you have higher
budget. Within each option, you can add Anti-reflective coating,sunglasses
tints or upgrade to Polarized lenses or photochromic lenses.
With our quality control system in place, you can rest assured
that you will always get the best quality lenses for your
prescription at unbeatable price.
In semi-rimless frames, groove is created
to hold the nylon which supports the lenses to the frame structure.
The groove weakens the lenses making it more subject to chipping.
We recommend impact resistant lenses for semi-rimless frames.
Impact resistant lens materials include Polycarbonate, high
index 1.60 and high index 1.67 lenses.
If the wearer is a child or the glasses are to be worn in
frequent sports activity, then it is a good idea to choose
impact resistance lenses.
Please note we highly recommend impact resistant lenses for
semi-rimless frames and child wearers. However, due to relatively
high cost of impact resistant lenses, we do not enforce the
use of impact resistant lenses for semi-rimless frames and
child wearers. Please take extreme care in handling the semi-rimless
frames fitted with none impact resistant lenses (CR39 or index
1.56 lenses). Detailed warranty and return policy can be found
Why do my lenses need grinding?
You may find that many of our eye glasses
lens packages use ground lenses. All of the lens packages
for bifocal, progressive and computer lenses and prescription
sunglasses use ground lenses. Most of the photochromic and
polarised lenses are ground lenses.
Simply put, ground lenses are custom-made lenses. Your lenses
are specially made by a grinding procedure from a blank polymer
that has a certain front curvature. Grinding removes the extra
thickness from the lens to make the lens thinner. Lens grinding
takes place after the lab receives your prescription. Orders
with ground lenses usually take longer, some extra 3-5 days.
Ground lenses are usually used when your prescription has
a high power range. Sports eyewear and prescription sunglasses
normally have higher front surface curvature and larger frame
sizes and mostly can only be fitted with ground lenses.
Please note the following text is for your information
only. You do not have to worry about the difference between
different lens materials in order to choose your lenses.
Our smart lens program will present you with only the lens
options that are suitable for your prescription.
about UV Protection
UV protection ensures your eyes don't suffer any sun-related
damage, sun protection lenses screen out 100% of harmful
UV radiation. All the lens materials listed below, apart
from CR39 and mid-index 1.56 lenses, are manufactured with
plastic lens - CR39
Most lenses are plastic, the least expensive plastic used
for eyeglass lenses is CR39 lenses. It is suitable for prescription
with lower sphere.
mid-index 1.56 plastic lens
These lenses not only provide you crystal clear vision,
but also manufactured with scratch resistant coating. They
are lighter, and thinner ( 37% thinner and 36% lighter than
most CR39 plastic lenses), therefore they are more comfortable
to wear than CR39 lenses if your prescription has higher
Polycarbonate lenses are virtually shatterproof and are
highly recommended for children and active adults. Polycarbonate
lenses are lightweight (27% lighter than ordinary plastic
lenses), safer, thinner and flatter. Plus, they have built-in
UV protection. It is suited for rimless frames.
Polycarbonate lenses are not resistant to chemicals such
as acetone or methylated spirit, which is commonly used
in optical store to remove the marking on the lenses.
Trivex 1.53 lens (also known as Trilogy
or Phoenix )
It is a new plastic lens material that is being used as
a substitute for polycarbonate lenses. It is optically superior
to polycarbonate in that it has less distortion than polycarbonate
and it is lighter. Trivex 1.53 is resistant to chemicals
such as acetone or methylated spirit. Like polycarbonate
it provides 100% UV protection and it is extremely durable
(ten times more impact resistant than ordinary CR39 lenses).
Most importantly, it is a great substitute for polycarbonate
lenses that need to be tinted, because it can be easily
tinted but polycarbonate cannot.
1.74 super high index lens
This is the most upper market plastic lens. Suitable for
very high minus prescription. They are manufactured with
UV-protective coating, anti-reflective coating and scratch
resistant coating. However, these lenses are not tintable
and not available with polarizer.
Anti-reflective coating, also called multi-coat or M/C, is
a greenish tint on the surface of the lenses that reduces
the light reflection on your glasses. You'll see more clearly
and comfortably under general lighting condition, for example,
when driving at night, watching TV, using a computer, reading.
It is recommended for any type of prescription eyeglasses.
Another benefit for eyeglasses: people can see your eyes,
not your lenses.
In Sunglasses, anti-reflective coating is beneficial when
applied to the back surface of sunglasses to eliminate "bounce-back"
reflections when you are facing away from the sun. Anti-reflective
coating on the prescription lens insert for DJ sports type
of sunglasses can reduce the reflection from inside of the
large sunglass shade.
Scratch Resistant Coating
We provide scratch resistant coating on all lenses that we
sell at no additional charge.
UV protection blocks ultraviolet light from damaging our eyes.
High index lenses e.g. polycarbonate, 1.60, 1.67, 1.74 provide
built-in UV protection. Polariser or photochromic options
provide built-in UV protection. UV Filter is strongly recommended
for tinted prescription sunglass lenses or eyeglasses that
will be worn outside, with lenses made from CR39 or 1.56 material..
All of our prescription glasses can be ordered with sunglass
options such as tints, polarised or photochromic lenses. It
costs as little as $25 extra for sunglasses tints when you
purchase your prescription
. To order discount prescription sunglasses, simply
choose your sunglasses options (sunglasses tint, polarised)
when you choose lenses for your eyeglasses.
A sunglasses tint is simply a coloured tint that gives you
great prescription sunglasses. Our tinting options offer you
either grey or brown tint.
They provide improved outdoor vision with better contrast,
clarity and depth along with more vibrant colours perception.
And because they reduce surface glare, they're ideal for activities
like fishing, boating, driving and snowing sports. They also
make great driving sunglasses, especially at dusk. As another
plus, polarised lenses provide 100 percent UV protection regardless
of the lens material used for the lenses.
light sensitive lens
Photochromic Lenses contain light-sensitive molecules that
darken and lighten according to the intensity of ultraviolet
light. It clears indoors, darkens outdoors, providing visual
comfort without the need to change glasses. People who participate
in activities that involve frequent going indoor and outdoor
often find them most helpful and convenient. Similar to polarised
lenses, Photochromic Lenses provide built-in 100 percent UV
protection. We use Sunsensors for 1.56 index photochromic
lenses, Transitions® lenses+
other index photochromic lenses.
Photochromic lenses are available with most of plastic material
mentioned above except 1.74 super high index lenses. We use Sunsensors for 1.56 index photochromic
lenses, Transitions® lenses+
other index photochromic lenses.
One drawback of photochromic lenses is that photochromic lenses
are not dark inside a car. This is because lens darkness change
is the effect of ultraviolet light. The UV light is blocked
by the car windows similar to inside a house. Glasses with
photochromic lenses are not recommended to be used as dark
sunglasses inside a vehicle, for example, for driving.
These are polarised transition lenses in brown colour. Combining
two of the most advanced technologies found in the eyeglass
industry today: polarisation and transition photochromic technology,
drivewear® lenses remove glare and adjust to varing light
conditions behind the windshield of any car. Unlike transition
lenses, drivewear lenses do not become clear indoor. Drivewear®
lenses are available for prescription sunglasses.
| *Prices are subject to change
+Transitions is a registered
trademark of Transitions Optical, Inc.
++Drivewear is trademark of Younger