Check with the rnib or LOOK for advice.

Citizens advice say

An optical voucher gives you help towards the cost of contact lenses or glasses. You’re entitled to one if: 

you’re less than 16 years old 

you’re aged 16, 17 or 18 and in full-time education 

you’re a prisoner and are on leave from prison 

you can get an NHS complex lens voucher, which are for people with very high prescriptions. The optician who does your eye test can tell you if you’re eligible for one. 

you currently get Income Support 

you’re getting Universal Credit and meet the eligibility criteria

you get Income-based Jobseeker’s Allowance 

you get Income-based Employment and Support Allowance 

you get tax credits and meet certain criteria 

you have an NHS HC2 certificate and are on a low income.

You could also be eligible for an optical voucher if you have an HC3 certificate.  

How can I get a complex lens voucher? 

If your prescription is for lenses that are -10 or +10 dioptres or more, you’ll be eligible for a complex lens voucher. If you need a prism-controlled bifocal lens, you’ll also qualify. 
The voucher means you’ll get money off the cost of your lenses, which is currently £14.60 for single vision lenses and £37.40 for bifocal lenses. 

I don’t get help and have optic atrophy, nystagmus and bitemporal hemianopia - turns out the fact I get Personal Independence Payment due to a visual impairment doesn’t make me eligible.

If you are in USa you can get medicaid, depending on your income, so you can ask what would be the top amount you can get per year/month and still get medicaid. i got glasses, didn't work. : so well. made things clearer, but still couldn't see stuff so good. :/