- quote -

FWIW, I attempted to adjust to bifocals for about a year without success - I
couldn't get used to the abrupt change when shifting from the distance
correction to the reading correction - however the first time I put on my
progressives I immediately knew they would work because of the smooth
transitions. It only took a few days for my brain to forget that there were
different corrections in different regions of the lens. I've been wearing a
Hoya progressive lens for a few years which my OD recommended in part
because I was hoping to be able to wear them while using the computer (wider
mid range channel). The quality of my vision is excellent with this lens,
but I cannot wear them for computer work - the mid-range channel is too
small. I doubt that any progressive would be adequate for computer work.
Separate single vision glasses for the computer are the best solution IMHO.

On 16 Jan 2007 10:19:49 -0800, "Mark Sabiers" <mark.sabiers[at]comcast.net> wrote:


- quote -

Aspheric lenses do not improve the visual acuity, they only allow the use of
flatter curves, which would normally increase oblique astigmatism and power
error when you look away from the lens center. Asphericity by itself, except for
reduced magnification in moderate to high plus, is beneficial visually only in
very high plus Rxs, probably above about +10D.

- quote -

It's rare, occurs mostly in lower powers, and that's usually associated with
internal and back reflections, easily remedied with the use of AR coatings.

- quote -

Bingo.

With your Rx, objects should be clear from about 25" to infinity through the
distance portion of the glasses, so there's probably no need for an
"intermediate" or separate glasses.

Robert Martellaro
~~~~~~~~~~~~~~~~~~
Optician/Owner
Roberts Optical
Wauwatosa Wi.
~~~~~~~~~~~~~~~~~~
"An expert is a person who has made all the mistakes that can be made in a very narrow field."
- Niels Bohr

Mark Sabiers wrote:

- quote -

nationally, I'd guess about 10% don't or can't adjust to them. My stats
are a little better than that because 1. I'm very careful in fitting
them, 2. I only use premium progressives, and 3. I talk a lot of people
out of them before they even try them. So my non adapt rate is about 5%.
Still way too many, but thankfully there's always a non-adapt free
remake available for at least 90 days.

w.stacy, o.d.

Thank you for your response. This helps clarify for consumers like
myself.

William Stacy, O.D. wrote:
- quote -

Understood. When the optometrist drew a diagram showing that
progressives have an intermediate zone that is only the center area of
the lens, I started wondering whether it would feel like looking
through a tunnel.

Yes, I am trying to determine whether I will adjust to progressives (if
lenses and frames are properly fit) or I am one of the few people that
will never be able to adjust. Are there any statistics for this?

- quote -

Ok, so asking for non-aspheric progressives is nonsensical - thanks.

- quote -

Thank you for the lens recommendations. I will pursue these locally
and hopefully find an all-purpose solution. Right now, I have moved my
monitors back a couple of inches to temporarily deal with the focus and
eye strain issues.

- quote -

Mark A wrote:
- quote -

Thank you for sharing the details. This helps consumers like myself to
understand better.

- quote -

Can the distance area of the lens be non-aspheric by being atoric? If
I pursued progressives, would I request progressives with atoric for
distance? I'm trying to determine what is reasonable to request of an
optician/lens manufacturer/lens grinder vs. what is nonsense.

- quote -

Ok, that explains my experience, thanks.

- quote -

Thanks for the other lens recommendations. Yes, now to find an
experienced optician in or near Fort Collins.

- quote -

Interesting thought. Good vision is the top priority. I admit to
having a preference for one pair of glasses.

- quote -

I believe my current SV lenses are 1.60 index and I have been happy
with them until presbyopia kicked in at 48.

- quote -

This is the key question. I have been assuming that a lifetime of
wearing non-aspheric lenses has caused the visual portions of my brain
to be adjusted to the distortion that non-aspheric lenses have so that
I will not be able to adjust to aspheric lenses. Are there people that
never can adjust or is the real issue what you mentioned above: proper
frame and lens fit to my eyes?

About the adapting period - what is considered tolerable symptoms
during those couple of weeks? A couple of weeks is how long I
previously tried with SV aspheric lenses before I gave up and was able
to revert to SV non-aspheric. How might one tell if one is going to
adapt vs. never adapt?

Thank you again for your response,
Mark

Mark Sabiers wrote:
I am led to believe I have always worn
- quote -

probably true, since aspheric single vision lenses are a fairly new
phenomenon.
- quote -

It might work, and might not. Progressives have narrow intermediate
zones and might not be suitable for computer use. In addition, if
aspheric single vision lenses bother you, progressives probably will too.

- quote -

Only in lined bifocals and trifocals. All progressives are aspheric.

So far, I have questions
- quote -

The Varilux Comfort has a very narrow intermediate zone. The GP wide is
a bit better, but I'd consider the Hoya ECP or the Varilux Physio if
you must have one pair of glasses that does everything. If you go this
route, you might not like how they work for computing and may end up
with a 2nd pair of computer glasses (SV non-aspheric of course).

w.stacy, o.d.

"Mark A" <nobody[at]nowhere.com> wrote in message
news:8MadnacmPra3ZDbYnZ2dnUVZ_qunnZ2d[at]comcast.com...
- quote -

BTW, in the Denver area I would recommend Europtics as optical shop that has
some very good opticians. 4 locations in Denver area, but it may be a drive
from Ft Collins.

http://www.eoptics.com/

"Mark Sabiers" <mark.sabiers[at]comcast.net> wrote in message
news:1168896911.424014.158740[at]a75g2000cwd.googlegroups.com...
- quote -

All progressives by definition are aspheric because of the add power for
reading, and the transition between distance and reading powers. Some
progressives are fully aspheric in the distance portion and some are not,
which is probably what you mean. Some lenses are atoric, which means that
they have the power ground on both sides of the lens.

The reason you had problems with the aspheric lens is that they were not fit
properly for your frames and lenses. The optical center of the lens must be
centered (left/right and up/down) on your pupil (except for a small offset
factor that we will not discuss here). Do not purchase new lenses from the
same person who tried to fit you with aspheric lenses in the past.

For your rather high power Rx, you probably would want a fully aspheric
progressive lens from a premium lens manufacturer and design. This
automatically rules out Lenscrafters, Pearle, Sears, and a host of other
large optical chains who sell mediocre lens designs. Almost all premium
progressive lens models are aspheric or atoric.

The Varilux Comfort is a fairly old design and might be OK for someone with
a relatively weak Rx, but I doubt you would be happy with them The Varilux
Panamic or Varilux Pyhsio will be much better for a strong Rx. There are
also other premium lens designs available from Zeiss, Rodenstock, Hoya, etc.
The key is to get an experienced optician to fit your frames and lenses.
Preferably someone is over 40 with a lot of years in the optical business
should fit you (and who also wears progressives).

You might want to consider computer glasses instead. This will give you good
vision at computer and reading distance, plus a little bit of vision up to
about 10 feet. But you cannot use these for driving (just use you existing
lenses for that).

One other thing that can make a very big difference is the lens material
(each with its own index of refraction). Most lenses come in a range of
materials (indexes). Someone with your strong Rx should avoid polycarb (1.59
index) like the plague. You would probably want 1.67 or 1.60 index lens
material. If you don't care about the aesthetics of thick edges, then 1.60
would give you better optical quality. If your optician recommends polycarb,
immediately go somewhere else.

Be forewarned that like any new progressive wearer, you will be freaked out
when you first put them on, but if they are a good design and fit properly
you will adapt to them in a few weeks. If you don't adapt, then almost all
manufacturers will remake them in a non-progressive design, bi-focals, etc
at no extra charge.

I am transitioning from single-vision non-aspheric lenses to bifocal
glasses.

I have been a full-time glasses wearer for more than 40 years. 4 years
ago, unknowingly I received single-vision aspheric lens. After 2 weeks
of blurry vision, eye-strain and headaches, the provider agreed to have
single-vision non-aspheric lenses made. The blurry vision, eye-strain
and headaches all went away. I am led to believe I have always worn
non-aspheric lenses.

Since I work full-time at a computer, it has been recommended that I
get progressive lenses that include intermediate. My new perscription
is:

Sphere Cylinder Axis Prism Add
OD -7.25 -050 169 + 1.25
OS -7.75 -075 053 + 1.25

Does anyone in this group know of any lens manufacturers and providers
that can make this perscription non-aspheric? So far, I have questions
into Varilux (for Comfort) and Hoya (for Hoyalux GP Wide). I would
like to understand any progressive options before I compromise by
getting non-progressive lenses.

Thank you,
Mark Sabiers
Fort Collins, Colorado