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Science Forum Index » Medicine - Vision Forum » 8 base lenses non corrective
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| Guest |
 Posted: Fri Jun 08, 2007 6:43 pm |
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I have a pair of sunglasses that have a star reflection that comes
from sunlight being reflected form car windows, oncoming headlights,or
other reflected sunlight. The manufacturer says that my eyes may be "8
base sensitive"
I have several other quality sunglasses that do not exhibit this
problem. Anyone ever experience this ?
Foz |
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| michael toulch |
| Posted: Sat Jun 09, 2007 9:32 am |
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On Jun 8, 7:43 pm, f...@bellsouth.net wrote:
Quote: I have a pair of sunglasses that have a star reflection that comes
from sunlight being reflected form car windows, oncoming headlights,or
other reflected sunlight. The manufacturer says that my eyes may be "8
base sensitive"
I have several other quality sunglasses that do not exhibit this
problem. Anyone ever experience this ?
Foz
do you have other wrap-around sunglasses?
are you "8 base sensitive" in these as well? |
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| Salmon Egg |
| Posted: Sat Jun 09, 2007 3:59 pm |
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On 6/9/07 7:32 AM, in article
1181399547.358426.252740@p47g2000hsd.googlegroups.com, "michael toulch"
<michaeltoulch@hotmail.com> wrote:
Quote: On Jun 8, 7:43 pm, f...@bellsouth.net wrote:
I have a pair of sunglasses that have a star reflection that comes
from sunlight being reflected form car windows, oncoming headlights,or
other reflected sunlight. The manufacturer says that my eyes may be "8
base sensitive"
I have several other quality sunglasses that do not exhibit this
problem. Anyone ever experience this ?
Foz
do you have other wrap-around sunglasses?
are you "8 base sensitive" in these as well?
What are "8 base lenses"? Is it a trade name?
Bill
-- Support the troops. Impeach Bush. Oh, I forgot about Cheney. |
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| Robert Martellaro |
| Posted: Mon Jun 11, 2007 11:56 am |
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Guest
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On Sat, 09 Jun 2007 13:59:43 -0700, Salmon Egg <salmonegg@sbcglobal.net> wrote:
Quote: On 6/9/07 7:32 AM, in article
1181399547.358426.252740@p47g2000hsd.googlegroups.com, "michael toulch"
michaeltoulch@hotmail.com> wrote:
On Jun 8, 7:43 pm, f...@bellsouth.net wrote:
I have a pair of sunglasses that have a star reflection that comes
from sunlight being reflected form car windows, oncoming headlights,or
other reflected sunlight. The manufacturer says that my eyes may be "8
base sensitive"
I have several other quality sunglasses that do not exhibit this
problem. Anyone ever experience this ?
Foz
do you have other wrap-around sunglasses?
are you "8 base sensitive" in these as well?
What are "8 base lenses"? Is it a trade name?
Bill
-- Support the troops. Impeach Bush. Oh, I forgot about Cheney.
It's the base curve or front curve of the lens measured in diopters. Higher
numbers mean increased curvature. Interestingly, if there is no Rx, the back or
ocular curve is very close to, but not equal to the front curve. Here's why...
http://www.optiboard.com/forums/attachment.php?attachmentid=1837
In regards to reflections, I would check if the lenses have an anti-reflection
coating. I would also look at the quality of the optics i.e., waves, warpage,
unwanted prism and power etc.
Robert Martellaro
~~~~~~~~~~~~~~~~~~
Optician/Owner
Roberts Optical
Wauwatosa Wi.
~~~~~~~~~~~~~~~~~~
"Science is a way of trying not to fool yourself."
- Richard Feynman |
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| Salmon Egg |
| Posted: Mon Jun 11, 2007 2:57 pm |
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Guest
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On 6/11/07 9:56 AM, in article kguq63d552pme3bskf617b176qv86d3lmf@4ax.com,
"Robert Martellaro" <robopt@nospam.com> wrote:
Quote: What are "8 base lenses"? Is it a trade name?
Bill
-- Support the troops. Impeach Bush. Oh, I forgot about Cheney.
It's the base curve or front curve of the lens measured in diopters. Higher
numbers mean increased curvature. Interestingly, if there is no Rx, the back
or
ocular curve is very close to, but not equal to the front curve. Here's why...
Why not just call it a 125 mm or a 1/8 m sphere? Will that remove too much
jargon from the practice of optometry?
Bill
--
Iraq: About three Virginia Techs a month |
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| Mike Tyner |
| Posted: Tue Jun 12, 2007 6:23 pm |
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Guest
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"Salmon Egg" <salmonegg@sbcglobal.net> wrote
Quote: Why not just call it a 125 mm or a 1/8 m sphere? Will that remove too much
jargon from the practice of optometry?
From the start, opticians used diopters because millimeters aren't additive.
Lenses always have two surfaces and one must always a "base curve" in
calculations or tooling.
So you can't make lenses without a term that expresses '8 diopter base
curve'.
"8 base" certainly is jargon, but if the term didn't exist you'd need
something else.
What's twisty about the term "base curve" is that those who tool in minus
cyl consider the front surface to be "base" and with the old tools made in
plus cyl form the *back* surface was "base."
-MT |
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| Salmon Egg |
| Posted: Tue Jun 12, 2007 6:59 pm |
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Guest
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On 6/12/07 4:23 PM, in article
Epidne-YQ55Ht_LbnZ2dnUVZ_hmtnZ2d@giganews.com, "Mike Tyner"
<mtyner@mindspring.com> wrote:
Quote:
"Salmon Egg" <salmonegg@sbcglobal.net> wrote
Why not just call it a 125 mm or a 1/8 m sphere? Will that remove too much
jargon from the practice of optometry?
From the start, opticians used diopters because millimeters aren't additive.
Lenses always have two surfaces and one must always a "base curve" in
calculations or tooling.
So you can't make lenses without a term that expresses '8 diopter base
curve'.
"8 base" certainly is jargon, but if the term didn't exist you'd need
something else.
What's twisty about the term "base curve" is that those who tool in minus
cyl consider the front surface to be "base" and with the old tools made in
plus cyl form the *back* surface was "base."
-MT
How about a 8 diopter sphere?
Bill
--
Iraq: About three Virginia Techs a month |
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| Mike Tyner |
| Posted: Tue Jun 12, 2007 8:56 pm |
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Guest
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"Salmon Egg" <salmonegg@sbcglobal.net> wrote
Quote: How about a 8 diopter sphere?
Dunno. He has a drawer of "8 base" lenses, a drawer of "6 base" and some "4
base" and perhaps a drawer of "2s". The more curved, the more distorted.
"8-base-sensitive" is awfully jargonish but it's common usage if you're in
the business.
-MT |
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| Robert Martellaro |
| Posted: Thu Jun 14, 2007 4:03 pm |
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Guest
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On Tue, 12 Jun 2007 18:23:05 -0500, "Mike Tyner" <mtyner@mindspring.com> wrote:
Quote:
"Salmon Egg" <salmonegg@sbcglobal.net> wrote
Why not just call it a 125 mm or a 1/8 m sphere? Will that remove too much
jargon from the practice of optometry?
From the start, opticians used diopters because millimeters aren't additive.
1/f1 + 1/f2 = 1/f3 is a lot more awkward than D1 + D2 = D3.
Quote: Lenses always have two surfaces and one must always a "base curve" in
calculations or tooling.
So you can't make lenses without a term that expresses '8 diopter base
curve'.
"8 base" certainly is jargon, but if the term didn't exist you'd need
something else.
Radius of curvature in millimeters.
Quote: What's twisty about the term "base curve" is that those who tool in minus
cyl consider the front surface to be "base" and with the old tools made in
plus cyl form the *back* surface was "base."
-MT
With direct to surface freeform technology we can pretty much make the lens
anyway we want, limited only by the software/point files.
Robert Martellaro
~~~~~~~~~~~~~~~~~~
Optician/Owner
Roberts Optical
Wauwatosa Wi.
~~~~~~~~~~~~~~~~~~
"Science is a way of trying not to fool yourself."
- Richard Feynman |
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| Salmon Egg |
| Posted: Fri Jun 15, 2007 12:09 am |
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Guest
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On 6/14/07 2:03 PM, in article 7u4373hek2u87q4jgp0l4huanah1jl40nt@4ax.com,
"Robert Martellaro" <robopt@nospam.com> wrote:
Quote: On Tue, 12 Jun 2007 18:23:05 -0500, "Mike Tyner" <mtyner@mindspring.com
wrote:
"Salmon Egg" <salmonegg@sbcglobal.net> wrote
Why not just call it a 125 mm or a 1/8 m sphere? Will that remove too much
jargon from the practice of optometry?
From the start, opticians used diopters because millimeters aren't additive.
1/f1 + 1/f2 = 1/f3 is a lot more awkward than D1 + D2 = D3.
Lenses always have two surfaces and one must always a "base curve" in
calculations or tooling.
So you can't make lenses without a term that expresses '8 diopter base
curve'.
"8 base" certainly is jargon, but if the term didn't exist you'd need
something else.
Radius of curvature in millimeters.
What's twisty about the term "base curve" is that those who tool in minus
cyl consider the front surface to be "base" and with the old tools made in
plus cyl form the *back* surface was "base."
-MT
With direct to surface freeform technology we can pretty much make the lens
anyway we want, limited only by the software/point files.
Robert Martellaro
~~~~~~~~~~~~~~~~~~
Optician/Owner
Roberts Optical
Wauwatosa Wi.
~~~~~~~~~~~~~~~~~~
"Science is a way of trying not to fool yourself."
- Richard Feynman
There are mathematical terms, called curvatures, that are the reciprocals of
radii. The term curvature is usually used for curves in a plane but can also
be used for surfaces. There is nothing preventing curvatures from being
measured in diopters. Curvature and radius of curvature are discussed in
almost any beginning calculus text.
If you want to get fancier, look at a book discussing differential geometry.
They discuss the osculating paraboloid that gives a best fit to a surface.
There will be two radii of curvature and two curvatures (measurable in
diopters) at the point of contact. If the two curvatures are different then
there will, at a minimum, some (optometric) cylinder in the surface.
This differential geometry approach will be applicable to aspheric surfaces
as well.
Bill
--
Iraq: About three Virginia Techs a month |
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