Your daughter's prescription is for the correction of hyperopia
(farsightedness). There are several ways to minimize the thickness and
enhance the appearance of her eyeglass lenses. The two main methods by
which this can be achieved are by the use of high-index materials and
aspheric lenses. You will, of course, want to discuss this with an
optical professional in order to make the best choice for your
daughter. I suggest that you ask about ultra-high index aspheric
lenses (such as HYPERINDEX® lenses by Optima, mentioned below) and let
your optical specialist give you specific information that will help
you to decide. I've gathered some information that will provide an
overview of some of the options available.
"For anyone willing to pay the higher price, it's been possible for
years to turn even Coke-bottle-thick prescriptions into socially
acceptable, light-as-a-feather eyewear.
That's due to the magic of 'high-index' lenses that bend light
differently, so that even strong corrections can be thinner...
Eyeglasses with special aspheric lenses -- flatter than conventional
lenses -- can help improve the look of eyeglasses for those with
strong corrections, says Dr. Gregory Stephens, associate professor at
the University of Houston College of Optometry and a member of the
American Optometric Association Commission on Ophthalmic Standards.
These lenses are fitted closer to the face, eliminating the bug-eyed
look of some farsighted corrections and the tiny-eyed look of some
nearsightedness corrections as well as improving vision."
CNN: What are we doing to our eyes?
http://www.cnn.com/HEALTH/specials/eye.series/overview/
"For highly farsighted patients that dread looking 'bug-eyed', here
are some tips for selecting your lenses:
Choose an 'aspheric' lens. This is the most important factor which
reduces the lens center thickness, weight, and optical distortion.
Avoid rimless or 'rimlon' frames since these may add unnecessary
central lens thickness and overall weight."
Refractive Source: Lenses
http://www.refractivesource.com/patients/alternatives/glasses/lenses.htm
"High index lenses are made of materials that are compressed, or
denser, so the same amount of visual correction is taking place using
less lens material than traditional plastic or glass requires. 'High
index' means that the lenses are constructed of a plastic or glass
material that has a higher index of refraction. The 'index of
refraction' refers to the speed that light travels as it passes
through the lens material...
High index lenses are available in either glass or plastic. Different
manufacturers make different high index lenses, and what sets each
lens apart from the others is its index of refraction (IOR). The
higher the IOR, the denser the material. All things being equal, a
1.66 IOR material will result in a thinner and lighter-weight lens
than a 1.57 IOR material will. Generally, the higher the IOR, the
higher the cost of the lenses will be...
Just like high index lenses, aspheric lenses are also thinner than
regular lenses. But the thinness is accomplished with the lens design,
not just the lens material. Aspheric lenses are flatter than
conventional lenses.
In plus lenses for farsighted people, the curves flatten away from the
center, for a lens that doesn't bulge out as much. It also does not
magnify the eye, so the eye appears more natural. In minus lenses for
nearsighted people, the curves steepen away from the center, toward
the edge of the lens. This results in a thinner lens edge."
Agape Optometry Center: Lens Materials
http://www.agape1.com/lens_materials.htm
"Farsighted patients may use High Index lenses or polycarbonate and
they will be significantly thinner than Standard plastic
High Index lenses -- Plastic ophthalmic lenses that have a higher
index of refraction than standard (1.49). The higher the number, the
thinner the lens can be made...
Polycarbonate -- A very strong lens material -- thinner (1.5 mm, 1.0
mm) and lighter than Standard CR-39 plastic. Should be used for
children's glasses and in any work situation where flying objects
might occur. Glasses used for sports should be made of polycarbonate.
However, our experience is that polycarbonate scratches more easily
and distorts more (especially in higher prescriptions) more than CR-39
or High Index lenses
Aspheric Design -- A lens surface design that eliminates many optical
distortions -- desirable in higher prescriptions -- not available in
all configurations."
Eye Store USA: Key to Lens Materials
http://www.eyestoreusa.com/Prescriptions/PrescriptionDefinitions/LensMaterials.html
"High Index Lens Materials
These materials are thinner for the same lens power. People with high
Rx's will benefit from this lens type. In general, the higher the
index, the thinner the lens edge, but the more the internal distortion
and chromatic abberation. This type of lens is only worthwhile for
high to moderate Rx's. Polycarbonate lenses can be made thinner
without the risk of breakage, and this is another way to reduce edge
thickness.
Aspheric Lenses
This is another way to reduce lens thickness, especially for
farsighted patients. These lenses require precise centering in front
of the eye, but will reduce thickness and weight by about a third."
Briggs & Pitre Optometry: Spectacle Lens Materials
http://www.bpeyes.com/glasses.html
"In a completely different manner than high index, aspheric lenses
also end up thinner than conventional lenses, even when made in
conventional plastic.
In the case of aspheric lenses, however, this cosmetic thinning is
produced by the design of the lens, not by a higher index material.
Even so, many of the newer aspheric lenses are made of high-index
materials, providing the maximum in both thinness and improved vision.
Slimmer Profile
In an aspheric design, the lenses have flatter curves; this means
lenses do not 'bulge' out of the frame as much as regular lenses. The
side profile of aspheric lenses is thinner, which greatly enhances the
appearance of finished eyewear. While high-index lenses primarily
benefit people who are nearsighted, aspherics provide substantial
benefits for both nearsighted and farsighted wearers.
Less Magnification or Minification of the Eyes
Also, the flatter aspheric lenses end up positioned closer to the
face. This is a major benefit for anyone wearing a strong correction."
All About Vision: Aspheric Lenses
http://www.allaboutvision.com/lenses/aspheric-lenses.htm
"Advances in lens technology provide special benefits for children.
Kids are active, they're hard on their lenses, and they're very
self-conscious about their looks. Kids who wear thick glasses are an
easy target for the taunts of other kids. When it comes to glass and
conventional plastic lenses kids with strong prescriptions have the
unsightly 'coke bottle' or the 'bug eye' look. HYPERINDEX® 1.66 lenses
by Optima can change all that. Gone are the unsightly edges and
optical distortions. The advanced aspheric lens design allows crisp,
clear vision from edge to edge. This new material, with a 1.0 mm
center thickness, is the thinnest lens available for the best cosmetic
appearance. Also lens weight is reduced by 50% over conventional
(ordinary) plastic and 80% over glass lenses. The result? Lighter
lenses that won't slide down your child's nose or cause pressure
points. HYPERINDEX® 1.66 lenses are amazingly light so your child has
a degree of comfort never before possible."
Optima: Choosing the Right Lenses for Your Child
http://www.optima-hyper.com/frmadvan.htm
Optima is one of the leading names in the field of high index lenses.
Other manufacturers include Hoya, Seiko, Sola, and Zeiss. Here is a
chart that compares the thinness of several high index plastic lens
materials:
----------------------------------------------------------------------
Lens Material Refractive % Thinner Examples
Index than
Plastic
----------------------------------------------------------------------
1.74 high index plastic 1.74 up to 65% Hyperindex 174 (Optima)
1.71 high index plastic 1.71 up to 60% NuLux LX (Hoya)
1.67 high index plastic 1.67 up to 55% Super 1.67 (Seiko)
ViZio 1.67 (Sola)
Hyperindex 167 (Optima)
1.60 high index plastic 1.60 up to 45% Super 16 MX (Seiko)
Hyperindex 160 (Optima)
Clarlet 1.6 (Zeiss)
Polycarbonate 1.59 up to 40% Tegra (Vision-Ease)
Airwear (Essilor)
FeatherWates (LensCrafters)
----------------------------------------------------------------------
eyeTopics: Eyeglass Lens Materials
http://www.eyetopics.com/articles/38/1/Eyeglass-Lens-Materials
I have a personal interest in this subject, since both my husband and
I used to wear thick, heavy "Coke bottle" glasses that were so
burdensome that they actually made deep grooves in the cartilage of
our noses. We now look relatively normal (and our noses are not quite
so groovy), thanks to high index lenses. The difference between
standard lenses and lenses made of high index materials can be
remarkable. Scroll to the bottom of this page for a dramatic
comparison of the thickness of high index lenses and regular plastic
lenses:
The Eye Doctor: 1.66 High Index Plastic Lenses
http://www.theyedoctor.com/Lensestheyedoc/167highindex.html
My Google search strategy:
Google Web Search: farsighted OR hyperopic "thinner lenses"
://www.google.com/search?hl=en&q=farsighted+OR+hyperopic+%22thinner+lenses%22
Google Web Search: farsighted OR hyperopic "high OR higher index" lenses
://www.google.com/search?hl=en&q=farsighted+OR+hyperopic+%22high+OR+higher+index%22+lenses
Google Web Search: farsighted OR hyperopic "aspheric lenses"
://www.google.com/search?hl=en&q=farsighted+OR+hyperopic+%22aspheric+lenses%22
I hope this is helpful! If anything is unclear or incomplete, please
request clarification; I'll gladly offer further assistance before you
rate my answer.
Best regards,
pinkfreud |
