On Tuesday, 25 April 2023 at 09:21:13 UTC+1, Andy Burns wrote:
> Brian Gaff wrote:
>
> > I don't even know what they are in any case.
> I hadn't heard of them, they sound like a variation on varifocals, but
> with shorter range, e.g. between reading and TV distance, or between
> smartphone and talking to people round a pub table, rather than the full
> range between needlework and star gazing?
>
> Could be useful, but I can see you might end up with a pair for 1m,
> another for 2m, another for 3m, having a computer pair and a driving
> pair in enough hassle already
Having just had cataract surgery and having good long-distance vision for the first time in over 50 years, these are wonderful. Post surgery I have to have reading glasses for the first time in my life. They were prescribed by Specsavers, who call them super readind glasses. They are varifocal with a close-up reading range and the top half go up to two metres, theoretically but in fact go further. I am able to use them inside all the time without having to take on and off a pair of traditional reading glasses. Truly wonderful, Jonathan

On Tue, 25 Apr 2023 21:35:13 +1000, wrights...@f2s.com
<wrightsaerials@f2s.com> wrote:

> On Tuesday, 25 April 2023 at 09:55:44 UTC+1, Andy Burns wrote:
>> RDS wrote:
>
>> I have a single vision pair that's designed for screen use at arms
>> length, usually ok for checking messages on phone too, unless in a dingy
>> pub with pupils wide open.
>
> You are the only person I have encountered who accepts that the pupil
> and iris of the human eye affect depth of field.

I do too.

On Wed, 26 Apr 2023 04:59:56 +1000
"Rod Speed" <rod.speed.aaa@gmail.com> wrote:

> On Tue, 25 Apr 2023 21:35:13 +1000, wrights...@f2s.com
> <wrightsaerials@f2s.com> wrote:
>
> > On Tuesday, 25 April 2023 at 09:55:44 UTC+1, Andy Burns wrote:
> >> RDS wrote:
> >
> >> I have a single vision pair that's designed for screen use at arms
> >> length, usually ok for checking messages on phone too, unless in a
> >> dingy pub with pupils wide open.
> >
> > You are the only person I have encountered who accepts that the
> > pupil and iris of the human eye affect depth of field.
>
> I do too.

Basic optics. It works the same for eyes as for cameras and other
optical instruments. The smaller the aperture, the less curved is the
part of the lens which is in use, so the less focussing there will be.
Or to look at it another way, the more parallel will be the light rays
passing through the aperture.

--
Joe

On Wed, 26 Apr 2023 05:09:40 +1000, Joe <joe@jretrading.com> wrote:

> On Wed, 26 Apr 2023 04:59:56 +1000
> "Rod Speed" <rod.speed.aaa@gmail.com> wrote:
>
>> On Tue, 25 Apr 2023 21:35:13 +1000, wrights...@f2s.com
>> <wrightsaerials@f2s.com> wrote:
>>
>> > On Tuesday, 25 April 2023 at 09:55:44 UTC+1, Andy Burns wrote:
>> >> RDS wrote:
>> >
>> >> I have a single vision pair that's designed for screen use at arms
>> >> length, usually ok for checking messages on phone too, unless in a
>> >> dingy pub with pupils wide open.
>> >
>> > You are the only person I have encountered who accepts that the
>> > pupil and iris of the human eye affect depth of field.
>>
>> I do too.
>
> Basic optics. It works the same for eyes as for cameras and other
> optical instruments. The smaller the aperture, the less curved is the
> part of the lens which is in use, so the less focussing there will be.
> Or to look at it another way, the more parallel will be the light rays
> passing through the aperture.

Yep, I knew that back in school with pinhole cameras.

Being diagnosed with early-onset cataracts and advised that their
development will be slowed by the use of sun glasses in bright light,
I have a pair of varifocals with transitions
(https://www.glassesdirect.co.uk/buying-guides/lens-options) that I
use for everything. They are sometimes a bit slow to react when I move
from outside to inside though.

Peter Johnson <peter@parksidewood.nospam> wrote:
> Being diagnosed with early-onset cataracts and advised that their
> development will be slowed by the use of sun glasses in bright light,
> I have a pair of varifocals with transitions
> (https://www.glassesdirect.co.uk/buying-guides/lens-options) that I
> use for everything. They are sometimes a bit slow to react when I move
> from outside to inside though.
>

Sluggishness seems to be a common theme with reactive lenses. Most folk I
know who’ve tried them find there slow time to “recover” irritating.

Tim

--
Please don't feed the trolls

Tim+ <tim.downie@gmail.com> wrote:
> Peter Johnson <peter@parksidewood.nospam> wrote:
>> Being diagnosed with early-onset cataracts and advised that their
>> development will be slowed by the use of sun glasses in bright light,
>> I have a pair of varifocals with transitions
>> (https://www.glassesdirect.co.uk/buying-guides/lens-options) that I
>> use for everything. They are sometimes a bit slow to react when I move
>> from outside to inside though.
>>
>
> Sluggishness seems to be a common theme with reactive lenses. Most folk I
> know who’ve tried them find there slow time to “recover” irritating.
>
> Tim
>

FFS, THEIR! ;-)

Tim

--
Please don't feed the trolls

On 26/04/2023 13:08, Peter Johnson wrote:
> Being diagnosed with early-onset cataracts and advised that their
> development will be slowed by the use of sun glasses in bright light,
> I have a pair of varifocals with transitions

I have transitions, but I also wear a broad brimmed hat whenever outdoors.

> (https://www.glassesdirect.co.uk/buying-guides/lens-options) that I
> use for everything. They are sometimes a bit slow to react when I move
> from outside to inside though.

--
Colin Bignell

On 26/04/2023 13:08, Peter Johnson wrote:
> Being diagnosed with early-onset cataracts and advised that their
> development will be slowed by the use of sun glasses in bright light

Advised by who? Glasses Direct?

Tim+ wrote:

> Peter Johnson <peter@parksidewood.nospam> wrote:
>> Being diagnosed with early-onset cataracts and advised that their
>> development will be slowed by the use of sun glasses in bright light,
>> I have a pair of varifocals with transitions
>> (https://www.glassesdirect.co.uk/buying-guides/lens-options) that I
>> use for everything. They are sometimes a bit slow to react when I move
>> from outside to inside though.
>>
>
> Sluggishness seems to be a common theme with reactive lenses. Most folk I
> know who’ve tried them find there slow time to “recover” irritating.

+1

--
Bob
Tetbury, Gloucestershire, England

I want to die in my sleep like my grandfather did - not screaming and
yelling like the passengers in his car.

Peter Johnson <peter@parksidewood.nospam> wrote:
> Being diagnosed with early-onset cataracts and advised that their
> development will be slowed by the use of sun glasses in bright light,
> I have a pair of varifocals with transitions
> (https://www.glassesdirect.co.uk/buying-guides/lens-options) that I
> use for everything. They are sometimes a bit slow to react when I move
> from outside to inside though.

Shop around/check out something called CAN-C eye drops, available on Amazon
and doubtless other outlets.

These are a 1% solution of n-acetyl-carnosine, which is converted in the
anterior chamber of the eye to L-carnosine. The latter is not absorbed by
the eye so are ineffective in the form of drops. However, it has the
ability to dissolve immature cataract, although has no effect on mature
cataract. The original paper on this was published circa 1936. You can also
get L-carnosine as a dietary supplement.

If you fancy way out instead of science, try alcohol-free eye drops of
cineraria maritima such as Schwabe Cineraria Maritima Eye Drops 10ml (
non-alcoholic), also available on Amazon.

--
Spike

On Wed, 26 Apr 2023 13:08:24 +0100
Peter Johnson <peter@parksidewood.nospam> wrote:

> They are sometimes a bit slow to react when I move
> from outside to inside though.

According to my wife, who has used glasses for sixty years, the early
reactive lenses were quicker to clear. She noticed the difference when
getting new glasses once, and they haven't improved since, so it isn't
her perception.

Possibly the original type used a now-forbidden chemical, or the
current methods of glass processing don't allow the original material
to be used.

--
Joe

Spike wrote:

> Shop around/check out something called CAN-C eye drops

I've seen those being recommended, but the clinical studies show
"inconclusive results", so beware of buying expensive snake-oil.

e.g. Royal College of Ophthalmologists ...

"The evidence for the effectiveness of N-acetyl carnosine eye drops is
based on experience on a small number of cases carried out by a Russian
research team [Babizhayev]. To date, the research has not been
corroborated and the results replicated by others. The long-term effect
is unknown. Unfortunately, the evidence to date does not support the
'promising potential' of this drug in cataract reversal. More robust
data from well conducted clinical trials on adequate sample sizes will
be required to support these claims of efficacy. Furthermore, we do not
feel the evidence base for the safety is in any way sufficient to
recommend its use in the short term. More research is needed."

On 26/04/2023 15:17, Spike wrote:
> Peter Johnson <peter@parksidewood.nospam> wrote:
>> Being diagnosed with early-onset cataracts and advised that their
>> development will be slowed by the use of sun glasses in bright light,
>> I have a pair of varifocals with transitions
>> (https://www.glassesdirect.co.uk/buying-guides/lens-options) that I
>> use for everything. They are sometimes a bit slow to react when I move
>> from outside to inside though.
>
> Shop around/check out something called CAN-C eye drops, available on Amazon
> and doubtless other outlets.
>
> These are a 1% solution of n-acetyl-carnosine, which is converted in the
> anterior chamber of the eye to L-carnosine. The latter is not absorbed by
> the eye so are ineffective in the form of drops. However, it has the
> ability to dissolve immature cataract, although has no effect on mature
> cataract. The original paper on this was published circa 1936. You can also
> get L-carnosine as a dietary supplement.
>

I'd recommend anyone interested to also glance at the Wikipedia page on
the subject and perhaps also at the [Gold standard] Cochrane review
cited there.

https://en.wikipedia.org/wiki/Acetylcarnosine

--
Robin
reply-to address is (intended to be) valid

Spike wrote:

> Peter Johnson <peter@parksidewood.nospam> wrote:
>> Being diagnosed with early-onset cataracts and advised that their
>> development will be slowed by the use of sun glasses in bright light,
>> I have a pair of varifocals with transitions
>> (https://www.glassesdirect.co.uk/buying-guides/lens-options) that I
>> use for everything. They are sometimes a bit slow to react when I move
>> from outside to inside though.
>
> Shop around/check out something called CAN-C eye drops, available on Amazon
> and doubtless other outlets.
>
> These are a 1% solution of n-acetyl-carnosine, which is converted in the
> anterior chamber of the eye to L-carnosine. The latter is not absorbed by
> the eye so are ineffective in the form of drops. However, it has the
> ability to dissolve immature cataract, although has no effect on mature
> cataract. The original paper on this was published circa 1936. You can also
> get L-carnosine as a dietary supplement.
>
> If you fancy way out instead of science, try alcohol-free eye drops of
> cineraria maritima such as Schwabe Cineraria Maritima Eye Drops 10ml (
> non-alcoholic), also available on Amazon.

If either worked, they would be in regular use in ophthalmology. They
aren't, so they don't.
--
Bob
Tetbury, Gloucestershire, England

Diplomacy - the art of letting someone else have your own way.

On 26/04/2023 15:34, Joe wrote:
> On Wed, 26 Apr 2023 13:08:24 +0100
> Peter Johnson <peter@parksidewood.nospam> wrote:

>> They are sometimes a bit slow to react when I move
>> from outside to inside though.
>
> According to my wife, who has used glasses for sixty years, the early
> reactive lenses were quicker to clear. She noticed the difference when
> getting new glasses once, and they haven't improved since, so it isn't
> her perception.

I recall it tricky when driving into a multi story carpark.

> Possibly the original type used a now-forbidden chemical, or the
> current methods of glass processing don't allow the original material
> to be used.

I used to have glass photochromics, and the colour changing stuff was
throughout the glass so it looked darker where the glass was thicker.

The plastic ones I've had since have a photochromic coating so there
isn't any such effect.

--
Max Demian

Max Demian wrote:

> I recall it tricky when driving into a multi story carpark.

I thought photochromic lenses were decidedly *not* for driving?

On 26/04/2023 16:48, Andy Burns wrote:
> Max Demian wrote:
>
>> I recall it tricky when driving into a multi story carpark.
>
> I thought photochromic lenses were decidedly *not* for driving?
>

I thought that's because they don't work inside cars as the windscreen
blocks the UV that causes the transition.

I once had Drivewear varifocals. Drivewear works inside cars. I had no
problem with car parks, tunnels etc as 75% ain't all that dark. I might
these days.

--
Robin
reply-to address is (intended to be) valid

In article <20230426153450.5288a1bd@jrenewsid.jretrading.com>,
Joe <joe@jretrading.com> wrote:
> On Wed, 26 Apr 2023 13:08:24 +0100
> Peter Johnson <peter@parksidewood.nospam> wrote:

> > They are sometimes a bit slow to react when I move
> > from outside to inside though.

> According to my wife, who has used glasses for sixty years, the early
> reactive lenses were quicker to clear. She noticed the difference when
> getting new glasses once, and they haven't improved since, so it isn't
> her perception.

> Possibly the original type used a now-forbidden chemical, or the
> current methods of glass processing don't allow the original material
> to be used.

I'm pretty certain that my current lenses are plastic rather than glass.
That might explain the 'slow to clear' situation. But it doesn't bother me.

--
from KT24 in Surrey, England - sent from my RISC OS 4té
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On Wed, 26 Apr 2023 22:42:05 +1000, Colin Bignell
<cpb@bignellremovethis.me.uk> wrote:

> On 26/04/2023 13:08, Peter Johnson wrote:
>> Being diagnosed with early-onset cataracts and advised that their
>> development will be slowed by the use of sun glasses in bright light,
>> I have a pair of varifocals with transitions
>
> I have transitions, but I also wear a broad brimmed hat whenever
> outdoors.

Even when kissing Liz's feet ?

>> (https://www.glassesdirect.co.uk/buying-guides/lens-options) that I
>> use for everything. They are sometimes a bit slow to react when I move
>> from outside to inside though.

On 26/04/2023 17:38, Robin wrote:
> On 26/04/2023 16:48, Andy Burns wrote:
>> Max Demian wrote:
>>
>>> I recall it tricky when driving into a multi story carpark.
>>
>> I thought photochromic lenses were decidedly *not* for driving?
>>
>
> I thought that's because they don't work inside cars as the windscreen
> blocks the UV that causes the transition.
>
That's what I thought - until I sat reading in my living room, side-on
to a big picture window, on a bright, sunny day.
The lens nearest the window darkened, the other one did not.

> I once had Drivewear varifocals.  Drivewear works inside cars.  I had no
> problem with car parks, tunnels etc as 75% ain't all that dark.  I might
> these days.
>

On 26/04/2023 21:35, S Viemeister wrote:
> On 26/04/2023 17:38, Robin wrote:
>> On 26/04/2023 16:48, Andy Burns wrote:
>>> Max Demian wrote:
>>>
>>>> I recall it tricky when driving into a multi story carpark.
>>>
>>> I thought photochromic lenses were decidedly *not* for driving?
>>>
>>
>> I thought that's because they don't work inside cars as the windscreen
>> blocks the UV that causes the transition.
>>
> That's what I thought - until I sat reading in my living room, side-on
> to a big picture window, on a bright, sunny day.
> The lens nearest the window darkened, the other one did not.

Most modern windscreens use laminated glass with a film in the sandwich
that blocks UVB and most of the UVA.

--
Robin
reply-to address is (intended to be) valid

On 26/04/2023 16:48, Andy Burns wrote:
> Max Demian wrote:
>
>> I recall it tricky when driving into a multi story carpark.
>
> I thought photochromic lenses were decidedly *not* for driving?

Who said that? Never had a problem except as described. (In the days of
toughened rather than laminated windscreens, polarised sunglasses showed
odd effects.)

--
Max Demian

In article <u2840q$q0go$1@dont-email.me>,
rsandr@yahoo.com says...
>
> You can never have 1 pair of specs that works for everything once you
> reach a certain age.

Thanks to all for the viewpoints.
I have a little used pair of distance glasses I think I
shall have re-glazed and give it a whirl.

Cheers, Jim

Bob Henson <fake@obfuscation.net> wrote:
> Spike wrote:
>
>> Peter Johnson <peter@parksidewood.nospam> wrote:
>>> Being diagnosed with early-onset cataracts and advised that their
>>> development will be slowed by the use of sun glasses in bright light,
>>> I have a pair of varifocals with transitions
>>> (https://www.glassesdirect.co.uk/buying-guides/lens-options) that I
>>> use for everything. They are sometimes a bit slow to react when I move
>>> from outside to inside though.
>>
>> Shop around/check out something called CAN-C eye drops, available on Amazon
>> and doubtless other outlets.
>>
>> These are a 1% solution of n-acetyl-carnosine, which is converted in the
>> anterior chamber of the eye to L-carnosine. The latter is not absorbed by
>> the eye so are ineffective in the form of drops. However, it has the
>> ability to dissolve immature cataract, although has no effect on mature
>> cataract. The original paper on this was published circa 1936. You can also
>> get L-carnosine as a dietary supplement.
>>
>> If you fancy way out instead of science, try alcohol-free eye drops of
>> cineraria maritima such as Schwabe Cineraria Maritima Eye Drops 10ml (
>> non-alcoholic), also available on Amazon.
>
> If either worked, they would be in regular use in ophthalmology. They
> aren't, so they don't.

It depends what you mean by ‘worked’.

NAC is only effective on immature cataract, but by the time you see the doc
and get bumped up to ophthalmology with a complaint of
blurry/sparkly/cloudy/double vision, you might have had cataract developing
for 20 years, so NAC won’t be effective and it won’t be offered.

Up to that point you might never realise that you have immature cataract,
and so won’t be using NAC at a time when it’s most effective.

--
Spike