contact lens prescription query?

hampshirebabe

Hi, I went into specsavers today to get a copy of my prescription so I can order some lenses online, which they gave me no probs. But she gave me 2 prescriptions. The contact lens one is slightly stronger, which she said is because its curved and on the eye as opposed to the glass lens which is further away.
I've never heard this before, and never noticed it on the prescriptions I've been given, anyone else know about it?
Mary

EmehEm2005

I just 'googled' the subject.

Mike


http://www.eyetopics.com/articles/112/1/Contact-Lens-Prescriptions-Explained.html

Also
http://vision.about.com/od/contactlenses/Your_Guide_to_Contact_Lenses.htm

starving_artist

Yes my spectacle prescription is always about a diopter more than my contact lens one. My optician gave me the same explanation.

hampshirebabe

thanks, there's always someone on here who knows.

lisyloo

Also sometimes contact lenses (certainly torics) are made in certain prescriptions on.

So for example the manfacturer might supply the astigmatism values of 1.25 and 1.75.
If you are a 1.50 then your optician has to find you the best "fit".
Which might be a 1.25 with a stronger strength or 1.75 with a lower strength.

It's a bit like being a 6.5 shoe size but going into a shop that has only 6s and 7s.
Or being between a 10 and a 12 in ladies clothes and jsut having to take the closest.

The difference with glasses is that they are individually made to your prescription whereas contact lenses are only supplied in certain strengths.

ALWAYS_POOR

Yup, my prescription is exactly the same. Same explanation too. Basically I've always understood it to be because the contact lens is actually on your eye and your glasses are further away from your eyes. And also as lisyloo explained, glasses are made to measure so to speak.