[Closed] explaining an optical prescription

Opticians would be able to answer such questions, I speak to miine during the eye exam - you should try it.

i didn't think of the question at the time, one of those questions that comes up afterwards. had an explanation of PD and why i have two and that the numbers differ eye to eye.

[url= http://www.danda.co.uk/eye-care/your-prescription/ ]http://www.danda.co.uk/eye-care/your-prescription/[/url]

but what does cyl actually mean?

it means you have a funny shaped eyeball.

Most eyes are perfectly round.
Yours is the exact shape of a baked bean tin.

Probably.

DrP

The cyl indicates you have an astigmatism. If that's not a typo its a fairly large one and you need specs...

Your eyeball is an irregular shape. Don't worry most people have an astigmatism. Normally a bit smaller however...

If you imagine the Sph or sphere denotes a concave or convex lens making an image larger or smaller. The cyl or cylinder is a correction across the lens or eyeball. Basically your eye as you look at it is rugby ball shape. If that makes sense. The lens also has a correction to make the image "more round" therefore you need a correction across both meridians to allow for an image to be clearly focused in a horizontal plane...

If that makes sense.......

The + part means that you're longsighted the - part refers to you astigmatism.
Long and short sight are corrected with spheres, lenses which have the same power in any meridian.

Astigmatism is corrected by cylinders, lenses which have power in 1 meridian and no power 90 degrees to the first meridian. These 2 elements are put together to give you your prescription. The axis refers to the meridian of the cylindrical power.

Your astigmatism is rather high which could be due to irregular curvature in your cornea or lens or a combination of both. You'll likely need high index lenses to keep the lens thickness down. Contact lenses may be tricky depending on how much of your astigmatism is corneal and how much is lenticular. You'd either need toric soft contact lenses (not daily disposable) or rigid gas permeable lenses.

not a typo, i have a reasonably large astigmatism, and do wear specs....

just trying to understand. Basically is saying if you look at my eye one way i am long sighted +2 and if you look at it another way short sighted -8? or something else?

just ordered a set of 1.67 lenses (and weeped when i got the bill).... I have contacts as well which are ok most of the time, just curious as to what the numbers mean.

If you imagine the Sphere which changes the length of light entering the eye making it shorter or longer. The cylinder is a power that goes across the lens. When you look at the lenses themselves you should notice they are thicker at two points and thinner at two points. That's the cylindrical value. Sorry I've been up 3 days straight without sleep so a bit lacking in my explanations.

So imagine you have four muscles connected to the eye. One top, one bottom, one to the left and one to the right. If the two at the side are stronger they will pull your eye into a rugby ball shape so your eye is squashed. The cross power or cyl will counter act this giving you clear sight.

Best tip I can give is order your lenses from ciliary blue 🙂 you'd be astonished just how cheap your lenses are. Your paying for the wages of the optoms and staff.

well had a look at the cilary blue site and it seems i am out of range, so i guess that means price will be more than quoted. I may ask and see if, and how much they would charge to reglaze my Lindberg's so i have a spare pair of glasses.

Ah. I reckon it'll be cheaper. I can't remember the other place I have used before.

Sorry about the typo comment earlier. A stupid comment to make.

Lindbers. Nice frames 😉

IF you struggle getting a reglaze to your old specs find a good independant they will have access to some specialist labs, or might even glaze on site, to give you an idea my son is a +2.50 -5.50 and for skiing i bought him a pair of the cheap goggles from decathlon then glazed them myself to his prescription using some high base curve high index polorised lenses.

Basically if it has the right rim/fittings anything is glazable with in reason ( blank lenses can only be manufactured up to a certain diameter) just some frames fit certain prescriptions better

hustler, i am sure i can get them reglazed, just whether i can get it done reasonably cheaply, for a spare pair i don't really want to spend a lot of money.

I seem to remember the Zeiss Lenses the Lindberg's are fitted with being in excess of £200 which i really don't want to be matching. £200 being a bit less than the new pairs lenses are costing, the Zeiss's are c10 years ago, i should be grateful my prescription is fairly stable.

one other question.

found the packet in which the zeiss lenses came and the prescription is

Sphare -4.5 Zylinder 6.0 achse 0

My two eyes are a bit different, but the newer prescription has the sphere at +1.5? a bit confused by the difference?????

The packet will show the prescription transposed. So in theory sph: +1.5 / cyl -6.00 axis 180 is the same as sph -4.50 / cyl +6.00 axis 0

Your Lindbergh are they rimless? For a spare pair I shouldn't worry too much. If poss plump for a nice 1.67 lens or better if it exists now. Been out of optics a good 10+ years now.

OK thanks that makes some sense.

no they are the rimmed ones, was thinking about getting them done to 1.67, the cost of going any higher is IMO obscene

If it helps, most people have absolutely appalling sight. Even when they go around telling every one they have 20:20 vision, and even if they're right, it's rubbish. 20:20 is rubbish. I've got a -7.5 in one eye, I can't see my own cock and yet with glasses on, I know my eyesight is better than 90% of everyone else.

The people with the best eyesight on the planet are those that accept they have it and go and get some glasses to fix it.

When I was a kid and got my head kicked in every other day by a load of farmers kids because I wore glasses, my aunt would tell me they the joke was on them because if they thought I had four eyes, they needed glasses too. It might sound good but

a) It doesn't when you have blood coming out of your ear because you can't hear shit.
and
b) Saying it to them spurs them on to kill you quicker.

I am so glad that glasses are cool nowadays. It means a whole generation of kids won't get gravel rubbed in their face every day after school.

Main thing to check mrmo is they use a minimum blank size which is the uncut lens. That can make a massive difference to the thickness of a lens 1.67 or not. Ask the dispensing optician to go for minimum blank size. If they are qualified (a lot aren't) or know what they are doing they will know about it and sort it for you 😉

You'd find the cost of lenses even more obscene if you knew how much the optical labs charge . My wife works in the sales dept of one, the last lenses I bought cost me £20 the same lenses via an optician would've been just over £120.

Samuri, was talking to a colegue, who also wears glasses, and we came to the conclusion that most people who don't wear glasses have worse sight than those who do. They are the people who don't get eye tests, don't wear glasses when they need to and because it creeps up on you don't realise they have crap eyesight.

Waller, they better pick a small blank for the amount they are charging, and the detail that i believe the lens foundry are making the lenses to spec rather than trimming a standard blank!! the lens is 52mm i think so i expect a 55mm blank? certainly no bigger. I know how thick the lens should be, won't be amused if it isn't!

while we're on the subject, can anyone help explain what I should do about this...

I know my eyesight is bad.. I can't read the menu on the Tv screen, and I can barely read a text message on my phone.. numbers are worse.. ingredients on packets - no chance

If I relax my eyes now, I can't read what's on the screen on the laptop in front of me

yet when I go to the optician, I do OK on the tests and get a prescription for some weak reading glasses..
what am I doing wrong here..? I fear I may actually be slowly dying of eye sight related habitual stress

Minimum blank size won't make a massive difference to your prescription as the cylinder and sphere cancel each other out. But you would be better off going small.

Also the muscles don't change the shape of your eye Waller I hope you were talking metaphorically.

1.67 should look good, 1.74 would be better

Try and relax when you go to the opticians? Sounds like you might be straining your eyes to pass the tests. Relax, be truthful.

Relax? Sorry but that last comment makes no sense. An eye test is about finding the optimum prescription togivethe best corrected vision, not really to pass or fail.

The 'Axis 8' bit means you are part of the axis of evil, so you are now officially the enemy of The West. I'd get a second opinion if I were you, forums like this are monitored.

Here you go. This should provide some interesting reading for you:

http://eyewiki.aao.org/Physiology_of_Astigmatism

Best of luck with getting your specs sorted 🙂

[i]Relax? Sorry but that last comment makes no sense. An eye test is about finding the optimum prescription togivethe best corrected vision, not really to pass or fail. [/i]

Precisely. So if you go all tensed up, squint like crazy and strain your eyes trying to see what's there, you'll provide false results. Relax, if you can't see what's there, don't mess about, tell the truth, it's hard to see.

Samuri, No, that's no how it works

I'm lost then, sorry.
Yunki tells us that if he relaxes his eyes he can't read the screen on the laptop but when he goes to the opticians, he doesn't get a prescription that fixes things.

From that I'm guessing that when he goes to the optician he not relaxing his eyes (whatever this actually means) and is therefore providing false results which in turn stops the optician from providing him with the appropriate prescription.

What's your interpretation of his post?

By the sounds of it Yunki is describing presbyopia...the loss of accommodation (the ability to focus close up)thus making near tasks harder. Sounds like what he needs is reading glasses which is what he got, they should fix the problem, if not he should go back.

If you end up with a high cyl power - talk to your optician - it might be worth seeing what the lowest cyl power you can get away with is to keep your thickness/prices down especially for sports goggles/sunglasses/riding specs

Samuri, No, that's no how it works

Actually, by squinting, we automatically correct refractive anomalies (i.e. short/long sightedness), hence why if you lose your glasses, you can see 'OK' through really squinted eyes...

DrP