Varifocals, prescriptions and pupillary distance

[neilrj]

I buy Asda varifocals now, frames cheap as chips and varifocal at same price as std lenses. Very small sweet spot but my brain now adjusts immediately, though I'd almost given up on some very spendy local specialist optician's wide angle  (or somesuch geekspeak). With me it was just a matter of (some) time until my brain 'got it' now I can adjust in seconds to a new pair. The biggest expense in my glasses now is the transitions with anti-glare, hard coat etc. I've never tried bi-focal in anything other than dark tinted sunglasses as my wife days the bi-focal line in clear glass makes me look old, I'm 60 had so I'm' hardly a kid!

[Sergeant Pluck]

I’m getting used to them. First step was to swap the nose pieces to silicon ones, as suggested by the optician, so that they actually stay put. They didn’t have the right nose pieces when I collected the glasses, and that definitely hindered the adaptation process. The lenses do what they were intended to do (i.e. give me a little bit more strength at the close end and a very slight help for distance) although my previous specs, which were “office glasses”, do have less distortion at the sides.

Looks wise: well, they do fit well, probably better than the previous glasses on the nose, and I am getting used to the look.

The only remaining change I’d like to make is another readjustment of the earpieces to minimise contact with my hearing aids. There are acrylic sections at the ear so amenable to bending with a bit of heat. Dithering over whether to do this myself.

So it looks like it is on to the next stage, which is to get prescription sunglasses.

[TPMB12]

Just seen this thread. At my last eye test the optician asked me if I had right of reading glasses, bifocals or varifocals. Shocked me as I pay £280 for glasses and most of that is high index lenses, highest they do as standard. I asked if I needed them she said that I probably didn't right now but it's something to think about for the future.

Fast forward and it is 2 years later and I'm planning another eye test.  After hearing that my sister got a pair of varifocals for £280 from the chain I use and said they're very good I started thinking. It's been getting harder to read things and I am probably putting it all off for no good reason. So I'm going to ask about them.

My question here is what issues come with having a complex prescription? One eye is -10.25 the other is -9.75. Both were -10 or worse but one eye slipped below that -10 level a few eye tests ago.

I need high refractive index lenses,  I think 1.74. Is this possible with varifocal lenses? Is it going to be expensive? Eye wateringly so?

[hellymedic]

My varifocals are high-index and pricy but I'm nowhere near as myopic as you.

I suspect it's possible BUT at your prescription, centring the lenses with your eyes HAS to be spot on (distortion is proportional to the cube of the power of the lens) and varifocals give poor correction off-centre.

I'm hoping your optometrist can get things right first time but you might need to pester until they are right.

[ian]

I’m in the minus 7s and I didn’t leave with much change from £750. That was basically for the most expensive everything because I’m, erm, worth it or something.

[mrcharly-YHT]

Yes you can get high-refractive index varifocals.

The price will be eye-watering.

The pupil location in the lens (vertical and horizontal) is absolutely crucial. You can't do this at home, it has to be measured in the frames you will be wearing.

[ian]

I think £758, though that was a few years ago and I'm sure they're not cheap. I think the only thing I didn't get was the weird blue coating because they just make the skin behind them look like the colour of liver failure.

The other thing is that with a prescription that high, you're limited to small frames, otherwise they'll will be so heavy that your face ends up down by your navel which makes getting them right a bit of a faff and requires some skill – not something you're guaranteed in today's modern opticians, which are basically frame showrooms staffed by bored teenagers. Someone, one day, will explain why I need frames with a 'designer name' or brand on them because I'm sure I don't. It also makes the lenses more difficult to get used to, you have to train your brain to be very precise. When it comes to training, my brain is basically a cat. I'm happy enough now, though given the number of scratches I've inflicted on them, I probably need a new pair.

[Paul H]

When considering the value you should also be aware that the prescription for the near sight is likely to change quicker than that for the other distances.  I'm sure others will have a better grasp of the biology, my understanding is the eye muscles used to focus weaken and that is continues though not linier.  My first two pairs of varifocals needed replacing in under two years, my current pair are still usable after three, though I'm probably overdue an eye test. My long distance prescription has been the same for twenty years and little change on the medium distance.  I'm still using my seven year old varifocal sunglasses which are fine for everything except that near vision. I did consider that next time round I'd get separate reading glasses, but the convenience is such that I probably wont, I will tick less of the extras boxes than I would have for single vision that have always lasted me 5+ years.

[hellymedic]

The problem with presbyopia is that the lens stiffens. This stiffening is pretty rapid around the age of 50.. Once it is totally rigid, reading prescription won't change much.

Varifocal lenses NEED to be quite tall to accommodate near, middle and distant zones usefully and smoothly so lens size will be a compromise...

[ian]

Mine are, he says measuring them, 2.5 cm from top to bottom. I'm not bragging.

[TPMB12]

Well my prescription puts the thickest part of the lens at the outer edges,  corners more precisely. My glasses are generally wide and not too big vertically to reduce lens thickness. Do varifocals come out thicker than similar single vision lense?

[ian]

I don't think mine are any thicker and it's normal for the lenses to be thicker at the edges, that's how they work (if you are short-sighted).

[TPMB12]

But it is made worse by the prescription. As I got told by an optician, a larger blank disc with equal thickness edges gets ground down to your prescription. The focal point on that blank can be in the centre or more to one side.  Mine is more to the inside which makes my lenses a lot thinner on the inside edge but conversely thicker on the outside edge.  More central prescription it can be thinner all round I guess.

[hellymedic]

Well my prescription puts the thickest part of the lens at the outer edges,  corners more precisely. My glasses are generally wide and not too big vertically to reduce lens thickness. Do varifocals come out thicker than similar single vision lense?

No.
They'll usually be thicker at the top if you are short-sighted, as steeper concavity is needed for distance correction than for close-up vision.

[TPMB12]

Well my prescription puts the thickest part of the lens at the outer edges,  corners more precisely. My glasses are generally wide and not too big vertically to reduce lens thickness. Do varifocals come out thicker than similar single vision lense?

No.
They'll usually be thicker at the top if you are short-sighted, as steeper concavity is needed for distance correction than for close-up vision.

Just taken my glasses off to check. With the glasses inches from my face I can clearly see that they're thicker on the outside, especially on the corners of the slightly rectangular glasses. If they were round there would be a thinning to point inwards of the centre before thickening a little. Since they're wider than higher there's an even me pronounced effect.

Trust me I've got good enough eyesight close up  to see they're thicker in n the outer edges and especially the corners.

[mrcharly-YHT]

Helly means that varifocals Will be thicker at the top corners.

The reading prescription will be much weaker so it will gradually thin down the outside edge towards the bottom.

[TPMB12]

Aah! I misunderstood. Thanks for the explain.

[FifeingEejit]

I’m in the minus 7s and I didn’t leave with much change from £750. That was basically for the most expensive everything because I’m, erm, worth it or something.

Yeah my Dad's were something like that, although he did also insist on transition lenses particularly because he wasn't buying 2 pairs at varifocal prices.
Weird as feck seeing him without glasses now the cataract surgery's been done and fix it at the same time.