Is it better for my vision to be over-corrected, or under-corrected?

[Nicolex1661]

I ask because I am farsighted and I've been wearing contact lenses for about 12 years.  I am in my early twenties.  I would say about 5 years ago, an optometrist decided to dilate my eyes in order to receive, as he put it, a more accurate prescription because my eyes worked too hard to focus.  So while my prescription before this had always been in the +3 and +4 range, it got bumped up to something around +6.50 in the left eye and +5.75 in the right eye.  They said it would take some getting used to, but I no longer strained to see up close.  It became common among all my eye doctors (I switched doctors often for some reason) to dilate my eyes for a prescription without any communication with each other or anything.  Well, about 3 months ago, my prescription expired, so I went to another new eye doctor, and he didn't dilate my eyes, and my prescription went back to the +4 range!  I was definitely worried and told them at my fitting, so they raised it a little.  Now they're at +5.75 in my left eye and +4.50 in my right eye.  It's been a couple weeks and my eyes are straining a little again at work.  I was wondering if I should let them know, or if it would be better to get used it and let my eyes learn to focus again.  With the very high prescription, I was always worried that my eyes had become weaker because it seemed my vision without the contacts was a lot worse and I couldn't focus at all anymore.  Thank you!  I've tried to bring up my concern with my doctors, but it doesn't seem like a concern to them.

[JohnHaganMD]

Your last "doctor" did you a disservice by lowering your prescription. In a young farsighted person the only way to tell how much total farsightedness they have is doing the glasses test after dilation.  If done before it RX will only correct some but not all of the farsightedness and you have to do extra work both distance and near and it gets worse as you get older because your ability to focus at near weakens in everyone as we age. So your vision without glasses or contacts will get worse especially in your mid to late 30's and you will be in bifocals or reading glasses over contacts in late 30's

That being said since you were able to wear your full correction before and now you are not and are having eye strain you would generally be better going back to your full RX determined by dilating your eye. It will probably take a week or two to be clear again at first they will seem too strong for distance.

right now your are doing an extra +1.25 diopters of work all the time distance and near and that is tiring.