Which is better--a contact lens too weak or too strong?

Question

For the past year, I've switched back and forth between a 7.00 and a 7.50 in my right eye (contact lens). My eye doctor probably hates me because I keep switching. He wants me to stay with the 7.00, but it's too weak. The 7.50 is too strong. I need a 7.25, but they don't make that. The doctor says I need a 7.25, but since they don't make it, I should wear the 7.00 even though it's too weak. He said it's better to wear a contact lens too weak rather than too strong. I'd like to read up on this to make sure. Has anyone ever heard this or know where I can read about it? I'd like to know which is safer to wear. Right now I'm back on the 7.00. Also, does anyone know why they don't make a 7.25??? They go in .25 increments until you get to 7.00. After 7.00, they go by .50 increments. That sucks if you're an in-between like me.

I'm asking because they aren't God, you know. They can make mistakes (and he has---he prescribed something for me that isn't FDA approved and I told him it wasn't). I only hope to God it hasn't damaged my eyes.

My eye doctor told me they don't make 7.25---but maybe it's just my contact brand that doesn't make them...... I use Acuvue (I'm using the Oasys now)

I meant not FDA approved for contacts by the way (in my earlier EDIT statement).

Another edit-----I clicked on the link (about the 7.25) and none of them offer a 7.25 so it must have been an error by the site.

Answer 1

As you know, the Acuvue Oasys lens does not come in a -7.25. These are the available lenses::
8.4mm base curve / 14.0mm diameter
-0.50D to -6.00D in 0.25 increments, -6.50D to -12.00D in 0.50 increments
+0.50D to +6.00D in 0.25 increments, +6.50D to +8.00D in 0.50 increments

It is standard practice to prescribe the most "plus" when the exact power is not available or a patient shows no preference between powers. This is so that the eye fully relaxes when focusing at distance. So, -7.00D would generally be prescribed instead of -7.50D in your case.

To explain why this is preferred-- while nearsighted persons can usually see just fine with a lens that is too strong, the eye never relaxes fully. Over an extended period of time, the eye is very slow to fully relax and requires the extra power to see clearly. (The eye can return to normal when allowed to relax for a sufficiently long time.) When the extra power is worn, what you are trading is near vision-- how close you can hold something and still read it. This may not be a problem at your age.

If you are having trouble adapting to the "in-between" lens, it may be for a couple of reasons.

First, most people have a dominant eye (an eye that the brain prefers to see out of). That eye should be corrected the clearest. If both eyes can't be corrected the to the same degree, then the nondominant eye should be blurrier, caused by just a touch too much plus power. In switching between -7.00 and -7.50 in your right eye, you may also be needing to switch lens power in your left eye to maintain balance and to satisfy a preference for a dominant eye.

Second, most people are a little more nearsighted at night when the pupil is larger. Your preference may be changing with lighting conditions causing you to change your mind.

Finally, you may have a low amount of astigmatism that your contact lenses aren't correcting. If your eyeglass prescription is something like "-7.75 -0.50 x 010" then you have 0.50D astigmatism. The the ideal spherical (standard) contact lens power for this eyeglass prescription is -7.25D. Because the blur is caused by astigmatism, your vision would have the same amount of blur whether you looked through a -7.25D lens or a -7.50D lens-- you would be unable to decide which is better. In combination with a dominant eye (i.e. the nondominant eye is seeing clearer because it has less or no astigmatism), this could be a probable cause.

As for why they don't make a -7.25 lens-- it's because while a 0.25D difference is noticable, it isn't very noticable. Persons with higher prescriptions are usually quite satisfied to be corrected within 0.25D of their exact prescription. Also, it is the Acuvue Oasys that doesn't come in a -7.25D power. Other brands can be ordered in -7.25, but it is often more expensive since most manufacturers would put this in a "custom lens" line. Most manufacturers use 0.50 increments at higher powers. In the opinion of your doctor, the higher Dk (better oxygen transmission to the eye) of the Acuvue Oasys probably outweighs the benefit of an exact correction.

Answer 2

1

Answer 3

I'm not sure if you wear a -7.25 but the do make contacts with that particular script.

That's weird but this brand does. I looked it up myself since the other link was a fraud

See Link

Ok..try this one.

Answer 4

Wearing one too strong will mess you up. It will give you headaches stick with the weaker one.

Answer 5

Why are you asking strangers on the internet to second guess your doctor? He went to school a long time to be able to practice his profession. Listen to him.