Do NOT, and I mean under (almost) ANY circumstance, pay for Thinner lenses.
My whole life, with my "Strong prescription" (around the -4) I've always been advised to go with a High Index lens.
Since I found eyebuydirect (I'm not affiliated with them, but if someone is getting glasses, I'd love i you hit me up for my referral code)
I've been able to get these 'expensive thin lenses' for only about $150, to my door, not $600 locally.
I had every pair checked on the machine at the local optom, they're always exactly what I order.
Anyway, since they're affordable now, I never hesitated to get the thinnest I could afford....
Then a whole list of education kinda chanced upon me at the same time.
First, Youtube suggested something I'd never have looked up, one of those "Heal your eyes naturally!" type videos.
It was all bullshit, but one part made me google more.
It was something along the lines of "We're starting to learn that minor aberrations and interaction between reflections at the edge of an object are a key factor.... yadda yadda yadda".
Hmm... ok.... Google google google, yep, all checks out.... Previously expected the brain was able to correct minor aberrations, but now for people who don't have perfect eyes, maybe not.... ok.... yep....
Then I dug further. (In ABBE charts, the higher number, the better)
That article is from 2015, the importance of abbe has been speculated to be even greater recently.....
Hard Resin - is Index 1.5, normal 'plastic' lenses. CR-39
Yes, the ones with the best visual clarity are the cheapest.
The ones people 'scare you away from' as being big and heavy...
Yes, they ARE thicker, yes they ARE heavier, but we're talking single grams, and in a -3.75 Cyl prescription, less than a 1mm thickness change (using a ruler, not a vernier)
To my knowledge (I emailed EBD), 1.55 is still a form of modified CR-39 which is why it's abbe value is still 'OK'.
And Trivex is just stronger. (read here if you want; https://www.allabout...es/polycarb.htm)
But I wouldn't bother with this 'sacrifice' in clarity unless you're over a 5.0 prescription. (I'm not an optom, just very experienced in glasses by this point).
People will tell you they're thinner and more delicate, and OK, so they do scratch easier.
For people with only readers which spend most of their day on their shirt, rubbing on things, maybe the scratch resistance is worth it.
However, if you wear them all day, I don't scratch my eyes with sharp objects... I'm sure you don't.... it'll be no harm.
I used to use GLASS sunglasses, never once broke a pair, and I was rough on them. CR39 is MUCH stronger than Glass anyway.
I've asked my 2 local optoms, I can't find a single instance reported of plastic lenses 'shattering'.
Cracks? In extreme cases yeah, but never dangerous, no shards in the eyes, just broken glasses.
With my 1.7x lenses, which are polycarbonate, I honestly thought I was going colourblind.
I wouldn't get things wrong, but they'd 'flicker' before my eyes, and rotating my head slightly would clear it up.
My 1.6 Lenses were 'better' but still had this issue if I was tired.
I could focus, but I was still getting eye strain, which made 0 sense (until now).
I'm now wearing some 1.5 index glasses, the difference and clarity in the same prescription is phenomenal.
I paid $40 for grind lenses and frame, delivered (Over $600 locally!!) and I couldn't be happier.
Just thought it was information people should know.
Stronger than Glass. As clear as any lens we can make (Including glass). Cheap.
And the Cons? ....are overplayed for marketing.
Heavier (I don't feel it), Thicker (1mm [less?] at -4ish), Delicate (I call bull, try and break a $2 pair of readers from the chemist), Scratches easier (possibly, but if you wear them during all waking hours, who cares).
Just my over enthusiastic FYI for the day :)