Contact Lens Prescription Question?
May 3rd, 2010 | See the Top Answers to this Question Below
I always thought that if you have a prescription for contact lenses, yoyou can use that same presription for any type of lens. Recently I have been told that this is wrong, that each type of lens will have different numbers. Does anyone know if this is credible? It seems odd to me, after all, a presciption is a prescription, but it was an eye doctor who told me this. Any ideas would be great!
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Contact lens prescriptions are different depending on the brand of contacts. Different contact brands have different sizes and parameters. One brand with the same power may fit and another brand with the exact same power may not. They are also made of different materials and depending on your particular eye, one may not be as comfortable. When a doctor writes a prescription, they give your prescription based on how well you see and how well it fits. Is it possible for you to wear another contact? Yes, but the doctor will not take responsibility for what happens to your eye if he/she hasn’t confirmed a proper fit.
On a side note, toric lenses (for astigmatism) don’t always come in the same prescription. For example, if your eyeglass prescription is -2.00-1.50×95, one brand of contacts may only make -2.00-1.50×90 and another brand may only make -2.00-1.50×100. How would you know which one to use? That’s what the doctor’s for.
I wear contacts and as far as I know you are right. A prescription is a prescription. Those numbers, like 5.5 or 7 or whatever are the strength of the lens. This should not change from brand to brand or from your glasses to your contacts. If you are switching to night and days or some specialized sort of contacts it could change. Or if your eyes have changed the prescription will of course. But other than that the numbers are set.
I’m a contact lens wearer, and I find that I need different degrees for coloured and clear contacts. (A difference by almost 50-100 degrees!) I’m not sure why though, maybe its a brand difference.
A prescription tells you how bad your myopia, long-sightedness, or astigmatism is. It shouldn’t vary according to the brand of the lens.
this is a common misconception, and your doc is right. part of the "prescription" is designating the brand, size, shape, material, water content, center thickness, optic zone, etc etc etc of the lens. those parameters can vary GREATLY between brands.
if you told me your Rx was -5.50, thats not near enough information. i would have no idea what lenses would be too tight or too loose or too large or too small or too dry, or have an optoc zone that is too small for your pupil, etc etc. i guarantee if you just started buying different brands, some of them you’d see poorly from and would feel terrible wearing, even if they were all -5.50.
so its a lot more complicated than most people assume. there’s a reason contact lenses are controlled by the FDA…they are fitted medical devices. its not nearly as simple as "a prescription is a prescription".