What strength eye glasses do I really need?
I'm trying to understand my vision. I'm 55 years old and I started wearing readers around age 45. I'm currently wearing nonprescription readers at 2.00. I've noticed when I try to look at something small like a medicine bottle,
the words seem to be blurry. If I get a magnifying glass it makes things more clear. When looking at my iPhone the words are somewhat blurry but when I move my phone to arm's-length it's more clear. Something I did find strange was one day I had my readers on and my prescription distance glasses on top of my head. The distance glasses fell over my readers and as I was looking at my iPhone everything became sharp and clear. I even mentioned that to my sister and she did the exact same thing and she said wow it was much more clear for her too. Yesterday I went to an eye doctor and he wrote a prescription of +.75 both eyes for distance which is the same as three years ago. And he wrote +2.25 in both eyes in case i wanted bifocals. I currently have no prescription readers. Three years ago I was wearing the same 2.00 readers and he told me they were too strong. Now yesterday he told me they're not strong enough if when I'm looking at my phone and it's blurry but after I push it to arms length it gets sharper. He says I need a stronger reader. Is that correct? Seems like if my phone for example is blurry holding it at a normal distance then it gets sharper as I push it away from me, then the glasses are two strong. I'm so confused.
A normal eye is focused in the distance. To see up close, muscles squeeze the lens of the eye, temporarily altering the shape, which shifts the focus closer. This process is called accommodation. The problem is that as your eye ages, the lens gets stiff with age (it happens to everyone), so it gets harder to accommodate.
Your eye is starting out a little bit farsighted +0.75. That means that you're accommodating a little to see in the distance, and you're accommodating a lot to see close. Since the natural lens of your eye is stiff with age (again, happens to everyone), you can't accommodate that much to focus on things that are really close.
When you wear your distance glasses, it cancels out +0.75 diopters of accommodation with the lenses in the glasses. So, you don't have to accommodate at all to see in the distance, and you have to accommodate less to see close. But very close is still too much for you.
If you wear +2.00 readers only, It's cancelling out the +0.75 diopters of far-sightedness, plus +1.25 to shift focus closer. It's like a normal-sighted person wearing +1.25 readers.
Due to your age, that isn't strong enough to see really close. When you wear your +0.75 distance glasses plus your +2.00 readers, that's like wearing +2.75 readers (they add together). +0.75 diopters will go toward cancelling out your far-sightedness, and the extra +2.00 will go toward shifting your focus closer. Shifting your focus closer by +2.00 diopters means that you can exactly focus on anything 50centimeters away from your eye. Anything closer than that will rely upon the accommodation of your eyes to shift the focus even closer. As I mentioned earlier, your ability to accommodate is limited by your age. So, if you want to hold something closer than 50cm and your eyes won't accommodate that much, you need stronger glasses.
You could buy +2.75 readers.
Let me put this another way. Readers shift the focus closer. Your eyes can shift the focus even closer, but this is limited by age, so you want your readers to shift the focus close enough that your eyes don't have to do anything. The stronger the readers are, the closer they shift the focus. Your readers alone are too weak, and your eyes can't make up the difference by accommodating.
Here's the really simple answer. Buy readers that are +3.00. That is what bottom part of the bifocals would be. (It's written as an ADD. So the bottom is +0.75 plus +2.25, which is +3.00)
Or, buy the bifocals.
Or, keep putting your readers over your distance glasses. That's a poor-man's version of bifocals.
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