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Understanding Contact lens Fitting

Posted: Thu 09 Nov 2006 3:41 pm
by alteclancing
I want to get some contact lenses fitted by a local opticians. But I need some understanding first. With Glasses I can get virtually no inprovment as usual but I've been raeding that contact lenses should make alot of change.

But the bit I don't understand is how does the optician know the prescription of contact lens to make ? i.e if you give him the prescription for your glasses that do not improve your vision surely using that prescription to make contact lenses will be a waste of time ?. My eyes have been just above driving standerds from the day I started driving and now they say they are borderline with some but very little inprovment with glasses so if the glasses are bringing my sight up to what it's always been surely that's the best i'm ever going to get?.

The main points are I don't want to walk into my local opticians and give him a recent prescription for glasses and he/she makes contact lenses to that prescription and they do no better than glasses.

What if the optician that said I had KC by looking at a conial graph was wrong. ADmitadly the systems seem right i.e I do alot of eye rubbing and my eyes are very random but much worse at night.

Posted: Thu 09 Nov 2006 4:06 pm
by John Smith
Hi there,

I'm sure one of our optoms will post more, but as far as I'm aware, a contact lens prescription is completely different from a specs prescription.

For specs, lenses are placed in front of your eye and you are asked to differentiate them.

For contacts, accurate measurements are made of your eye and a "fitting lens" is inserted into your eye- which will smooth the surface of the eye. A specs prescription is then taken wearing the fitting lens, from which a prescription for a working contact lens is made.

Of course, some of the variables in KC are very variable, so you will probably end up going through a few pairs of contacts before finding a good pair.

Best of luck in your quest - do please let us know how you get on.

Posted: Thu 09 Nov 2006 4:17 pm
by GarethB
If you have never tried lenses then I think optoms talking of a graft is a wee bit premature.

This link might help with an explanation as to why glasses do not work so well; Contact Lenses for KC

Posted: Thu 09 Nov 2006 4:27 pm
by alteclancing
Sorry I did not make myself claer with the graph thing. THe optician handed me a couple of images together with my letter to show the doctor what she was talking about I could have posted the images if I had not lost them to show you but one looked like a load of circles arround the eye with the circles not be exactly circle arround the centre of the image and the other showed a colour image of the eye which shows the steepness of the eye or something I wish I could find them then I could have posted for all to see.

Posted: Thu 09 Nov 2006 4:39 pm
by GarethB
What was done wasa topography of the cornea and from this a lens can be made to correct for the irregular astigmatism.

Some lens fitters use this graph to decide on a fitting lens rather than 'guess' and then do the normal test you are used to with this lens in your eye.

Very much doubt you would be able to take this to any highstreet optician and get a lens as we have found here many highstreet opticians such as the Specsaver and Boots have no idea about KC. However we do know about the exceptions.

Posted: Thu 09 Nov 2006 4:47 pm
by alteclancing
O.K found the images:

Image

Image

What do you think ?

Posted: Thu 09 Nov 2006 6:16 pm
by GarethB
As per my earlier post.

Wish I had readings as low as that :D

Posted: Thu 09 Nov 2006 6:43 pm
by alteclancing
FRom these pictures can you tell if I have KC. I'm looking arround the web and it says that from these images you can tell. But it's confusing me from the ring verification I'm guessing that the left eye looks amnormal i.e slightly oval near the center rings and the right eye looks uninfected. But as I say i'm confused. Also i'm reading something about the keratometer readings or something ?. As I say i'm trying do detirmine if there is cause to get these lenses or my eyes are just as good as there going to get. I appreatate your help by the way ?.

Posted: Thu 09 Nov 2006 6:51 pm
by jayuk
Alte

Your left eye is slightly worse then your right, but on both eyes the steepness is that the 6 o clock of the cornea

However, this would be normally classes as Mild\ borderline moderate KC depending on who is diagnosing you!

One thing I would say is that you are a rpime candidate for Soflex or Kerasoft lenses.....these are the more comfortable lenses known as Soft Lenses.

You have astigmatism and also bear in mind the following. Your glasses prescription and contact lens presecritpion would be different...generally. As the contact lens sits on the Cornea itself and thus to some degree introduces a "flattening" effect. Thus the light refraction would be different to that of a Lens in the glasses which is some cm's away from the eye....

HTH

Jay

Posted: Thu 09 Nov 2006 7:05 pm
by alteclancing
So I definetly have KC and in both eyes the left being worse than the right so contact lenses will definetly make my eyesight better than i'm getting with glasses ?

That redness at the bottom of the colour graph thing i.e the steepness is that how you can tell ?.

THis was my plan.

Confirm if Contact lenses would benifit me ?.

Go to Local optician i.e specsavers and ask for contact lenses.

I expect they will charge from the bottom up i.e eye test first and then contact lens test and then cost of lenses ?. So I might get away with soft lenses would those daily dispoable ones be o.k as I need to now what i'm asking for, any rough guide to cost ?