Rejecting new glasses

jpaul · 27 May 2019 at 08:26

Angilion said:
Higher refractive index lenses can reduce the clarity of peripheral vision. Some people are fine with that, either because they're not badly affected or because they accept substantial loss of peripheral vision as a drawback of wearing glasses

'problem' is the high st market (like the hearing aid one) uses subjective measures for lense quality and it is very difficult for the consumer to evaluate their products,
in the varifocal domain highstreets/specsavers don't attempt to compare their lenses with the higher prices essilor/hoya offerings, and unless the consumer forks out for the better brands you never find out what you may be missing out on, in terms of peripheral vision and focus areas.
(reposting from last varifocal thread) This hoya video attempt to explain this https://youtu.be/0q1RUUXLGjo?t=99
their/hoya 'personalised/custom' (the 'talk' the industry chose) lenses are ground on both sides, which customers can see should be beneficial, but the high st brands do not engage at that level.

Unlike the car market, say where you could test drive different brands ... it's a blind purchase -
when I come to replace the 10year old varifocals I have, if I choose specsavers and the lense quality is, subjectively worse, than what I have now when new, I'll reject them.
even if the prescription is right.. (scratch resistant coatings are definitely invaluable for lense life)

I rejected some rimless, PolyCarbonate varifocals in the past, because they have an execssive prismatic effect (chromatic eberration due to PC ) looking off axis .. and went to a different store.

( .... have 'which' evaluated glasses ?)

edit : online site i like , & would probably purchase form , good price reference ?

Mr Jack · 27 May 2019 at 16:05

danlightbulb said:
Standard short sightedness. I paid for thinner lenses too. I'll get on to them.

The thinner lenses may be the problem. They have more uneven distortion. When this happened to me they made me new lenses with reduced thinning (the middle option instead of the thinnest) and I was fine with them.

Smeghead · 28 May 2019 at 13:20

My latest (current) pair I had to have re-done once (Vision Express) because typically in the past I have always gone for narrow/rectangular frames, and these latest ones I wanted a change and chose some hipster-ish big, slightly rounded ones; the height from the top to the bottom of the lens is fairly big. When I first got them back, they must not have accounted for the height and where the frame/lens settles on my face, as when I wore them, everything looked really "busy" and the edges had a pincushion effect. They were fine when I got them back.

I had the exact same issue with some prescription Oakley sunglasses I got the other week (from RX Sport). Got them re-done and to be honest they still feel a tiny bit off, especially when I look directly down, but it's like 95% there and I don't wear them 24/7, so I can't be bothered to get them sent back again. It could also be that I'm still not fully used to the prescription as it is slightly stronger, but I'll live with it.

MrRockliffe · 28 May 2019 at 13:24

My girlfriend has always had excellent service from specsavers. Always re tightened glasses, adjusted fit etc without incurring any costs :-)

SpeedFreak · 28 May 2019 at 13:51

The opticians should be fine to remake the glasses, assuming the lenses are higher index (1.6) anti-reflective it will cost them about £20 to do this.

One of the first things to get them to validate is the optical centres. Ensuring they have been positioned correctly relative to your pupil distance is important and misalignment would cause distortion, even if the prescription appears perfect.

While it is not impossible for the lenses to be out of tolerance, in my experience it is very rare for an off the shelf lens to demonstrate visible distortion. To have the same effect from both lenses would be incredibly rare.

Assuming the above has been done, the next step should be a retest to rule out any error in your prescription.

Lastly, while lens intolerance does exist, it is more typically found among varifocal users, in single vision lens intolerance is quite uncommon but not entirely unheard of. Depending on your prescription a standard index lens (1.5) could be a viable alternative. While the frame shape and position of the optical centres has am impact, anything in the range of +2.50 to -2.50 should be fine for a standard lens.

danlightbulb · 28 May 2019 at 14:03

My contact lens prescription is -4.5 i dont know how that crosses over to glasses. My optician is swapping the thin lenses for the next thickest option but has said because the frames i picked are deeper than ones ive had in the past this is why im getting distortion. To be honest i would have thought there would be a means of compensating for this in the lens itself but obiously not, lots of people wear deeper frames these days they cant all be walking round feeling like they are about to step off the edge of a cliff.

Bassmansam · 28 May 2019 at 18:06

danlightbulb said:
My contact lens prescription is -4.5 i dont know how that crosses over to glasses. My optician is swapping the thin lenses for the next thickest option but has said because the frames i picked are deeper than ones ive had in the past this is why im getting distortion. To be honest i would have thought there would be a means of compensating for this in the lens itself but obiously not, lots of people wear deeper frames these days they cant all be walking round feeling like they are about to step off the edge of a cliff.

They probably have a lower prescription. Bot that yours is particularly high.

aardvark · 28 May 2019 at 18:17

Yeah it sometimes happens - often you just have to get used to it, assuming the prescription is correct.

I'm waiting for some new varifocals for the first time - i hope they are ok - i shelled out for the 2nd best lenses you can buy so hopefully less distortion.

Mr Jack · 29 May 2019 at 09:31

danlightbulb said:
To be honest i would have thought there would be a means of compensating for this in the lens itself but obiously not, lots of people wear deeper frames these days they cant all be walking round feeling like they are about to step off the edge of a cliff.

I'm not going to say there isn't a way of compensating for it but it results from fairly fundamental physics of how a lens works, so I think it'd probably be expensive to fix at the very least. I think it's more that different people have different tolerances for distortion in their vision, and get can used to different amounts. In the same way that some people get car sick, or sick on fairground rides, and some don't.

jpaul · 29 May 2019 at 10:26

with glasses you do learn to turn your head to optimize the image too, whereas with contacts, I guess not.

danlightbulb said:
My contact lens prescription is -4.5 i dont know how that crosses over to glasses. My optician is swapping the thin lenses for the next thickest option but has said because the frames i picked are deeper than ones ive had in the past this is why im getting distortion. To be honest i would have thought there would be a means of compensating for this in the lens itself but obiously not, lots of people wear deeper frames these days they cant all be walking round feeling like they are about to step off the edge of a cliff.

if the frame is deeper -(height yeh ?) are you now trying to look downwards, and expecting it to be in focus, at a greater angle than you would have with your previous shallower, glasses ? (without moving your head)

if they are putting in thicker lenses, so lower refractive index, chromatic aberration looking off centre should be reduced ... but I might ask them will this now be trivex material,
since like earlier comments, that has high R and lower Abbe eg https://www.2020mag.com/article/winning-the-high-index-numbers-game

aardvark · 1 Jun 2019 at 08:40

well, looks like i'm going to have to do this myself - got some varifocals for the first time a few days ago and boy they are bad.
Its not the transition between the top and the bottom (although they could do with moving the transition down), its the amount of lateral distortion in the sideways movement for the distance. Its very tunnel vision.

my previous distance pair were high index and did have some distortion, which i though was excessive, but this new pair are insane - they are so much worse. I only have to turn slightly off center and everything is really blurred. The old ones were at least more gradual.
And these are the 2nd best varifocal lenses they sell so not cheap.
If this is the best varifocals can get i'm going to have to carry 2 pairs of glasses around with me for the rest of my life.