OT: Any opticians here?

[Rod]

If they get at all cross, change opticians!

I changed to plastic many years ago and have never regretted it. I always managed to scratch the AR coating off glass lenses but have never had a problem with plastic. No noticeable scratches (to the wearer) even after several years of pretty careless handling. Most of them have been Nikon - but I have no idea if they are actually any better than other makes.

To get back on topic, I think that paint spatters come off plastic lenses more easily than glass.

[Mary Fisher]

Not according to our optician and our experience. You'd think so though. I suppose it depends what kind of plastic and glass is used.

[R D S]

Aside from the fact that I have been making lenses since 1990 I can't imagine any glass product being softer than the hardest plastic.

[Dave Liquorice]

I wear 'em all the time being rather shortsighted, anything more than about 6" from my eyes is at my maximum, unaided, focus point. Trouble is my aided mininmum focus is now around 12" so I have "dead band" of several inches where I can't focus aided or unaided. B-(

I have high refractive index glass, with coating, to cut down the speculars from TV lights etc. I've had plastic in the past but found them rather prone to damage. But we are talking maybe 15 or more years ago(*). I go for glass as the high refractive index keeps the lens edges thin and better wear.

(*) Modern plastics might be better. I believe they can match all but the really high refractive index glass these days but I still have my doubts about scratch resistance.

[Colin Wilson]

I was told the same about my left eye (i'm now 38) - it's never focussed, and even with glasses is unable to focus correctly (at all).

I'm "supposed" to wear glasses myself because of it, but they seem to magnify the problem, rather than alleviating it.

As a result, i'm crap at sport (no depth of field perception) and can't reverse to save my life :-}

[Alan J. Wylie]

There's one thing missing from the standard form that you need for a pair of specs - the PD (inter-pupillary distance).

simply the distance between the centres of your pupils - how far your eyes are spaced apart. There's no legal requirement for opticians to put it on the form, so guess what, they don't bother.

Some of the on-line spectacle manufacturers will ask for a photograph of you holding a ruler just below your eyes.

SPH is spherical - a standard lens

CYL is cylindrical - a bit like looking through a bottle - this corrects for astigmatism. The AXIS is the angle at which the cylinder is aligned (to the horizontal IIRC).

A positive cylinder at can be replaced by a negative cylinder at 90 degrees to it, with a corresponding change to the spherical power.

ADD is the near distance addition for reading - I assume you are over

45 and starting to suffer from presbyopia.

SV stands for Single Vision, as opposed to bifocals/varifocals.

[Bob Eager]

So was I, about my left eye (although it cannot see much further away than about a metre, at any time). Now I've had radiotherapy on it anyway, most of the central macula is dying but it still has OK peripheral vision! The next set of spectacles might as well have plain glass!

I can reverse OK (can still see out of the edge) but I find things like soldering a bit of a challenge due to lack of depth perception.

I'd really like a monocle; anyone know how easy they are to get made?

[Mary Fisher]

This is a d-i-y group ...

>

[Mary Fisher]

That's more or less what I said :-)

[Rod]

True - but he wants the monocle not to look like a pair of glasses cut in half with an angle grinder. He doesn't want to make a spectacle of himself. :-)

[John]

Well, my thanks go to everyone who posted on my off-topic subject - I've certainly learned a lot from it and it's been very interesting.

Specifically to Rick - yes, I do get slightly blurred vision in my left eye when wearing my distance specs (for driving). The best way I can describe it is to think of a motorway exit sign, far off in the distance. Without the specs, the words would be indistinguishable, just black lines on a blue background. With the specs, I can then read the words but they are slightly blurred.

And yes, I am in Preston so I'll definitely drop you an email off group.

Cheers mate, and once again, thanks to everyone.

John

[Bob Eager]

I do have one just like that...I made it when I went into hospital for the radiotherapy. But the lens is out of spec now, and I would like a 'proper' one..

For those interested, I just removed the arm and then cut off the nose bridge using large wire cutters! Why? The radiotherapy involves having a radioactive disc sewn to the back of your eyeball, and in my case it was there for 48 hours. During that time I had a large bandage and a lead patch, and was unable to wear glasses! I would have made a spectacle of myself but for elf an' safety reasons I had to be in a side ward and the nurses had to nurse in rotation to reduce their exposure to the ruthenium.

[Rob Hamadi]

FWIW, Tesco are apparently offering free eye tests ATM, according to this thread (which also mentions the inter pupilary distance problem):

[chris French]

In message , R D S writes

I'm wondering if the glass lenses are coated with something (anti-reflective coating or somesuch) and it is that which is scratching rather than the glass itself?

[Styx]

That is some seriously useful information. Thanks, Dave!

Do you know of anyone that can supply contact lenses in a similarly (cheap!) fashion?

Cheers,

Styx

[Mary Fisher]

That IS interesting. Rotating nurses eh? Hmm ...

Seriously why not have a pair of specs with plain glass in place of the unnecessary lens?

Mary

[Dave Baker]

BTW, I put that bit in because many years ago before I saw how it was actually done I assumed naively that lenses were individually made by taking a flat bit of glass or plastic and grinding/polishing that to the right curvature. Of course in hindsight that would be a very silly way of doing things and standard lenses come as blanks in every conceivable correction requiring only the frame shape to be ground in.

That's still a lot of blanks to keep in stock though because each strength of SPH correction needs to be stocked in every grade of CYL correction. The actual axis of correction is just a matter of aligning the lense in the frame properly which is done by setting it in the grinder at the desired angle.

Someone else can work out the possible combinations though.

Other than typing "cheap contact lenses" into Google nope. I've never had any dealings with the things.

[<me9]

And when you add bifocals (not to mention varifocals) they would need to be stocked in every permutation of axis (and L & R) as well.

From ones I've had from cheaper sources there is some compromises made. They're not always transparent at my prescription.

[Chris J Dixon]

Presumably adding prism into the mix calls for special orders?

Chris

[dennis]

Could be, however the coating is normally harder than glass.