CM measurements equalize at night

I have not found much related to this situation so I wanted to share.

My left eye has -0.25 more diopters of SPH than my right. In the mornings, my measurements usually reflect this, but other times it shows that my right eye needs more correction than my left. What I found strange though is that it has been much more common for both of my eyes to be the same cm measurement/SPH correction at night.

Another thing I wanted to add is that in close up, my right eye is lagging behind yet it is the dominant eye in distance vision.

  • Has anyone else experienced any of the two situations?

  • Does anyone have any interesting articles related to either scenario? (I couldn’t find one about the first)

  • Thoughts?

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It was weird, but a few nights ago both eyes were using the same correction to get to unfocused 20/30 even though the left eye should take -0.50 more. The next morning the left eye was easily seeing a light but pretty clear 20/30 uncorrected and right eye 20/70. They seem back to normal now, 20/50, 20/70 in the morning. Tonight though, the left, more myopic eye is clearer than the right. I have an idea the right cornea may be a problem with dryness. What does that say about the tear film and refraction?

The eyes work as a team and it kind of sounds like you might have one eye that’s more useful for distance and one eye that’s better for close-up. Sometimes people who have eye surgery to replace their lenses because of cataracts will deliberately choose to have one eye for distance and one eye for close up.

When I read the Snellen Chart my left eye is noticeably worse than my right. But I still do better reading with both eyes than I do with my dominant eye alone. Even though the left eye gives me a “not so clear” image it still seems to be helpful to pick up some additional details that the right eye can’t all by itself. Just like a baseball player throws with one hand and catches with the other hand, there’s probably some specialization going on where you’re favoring one eye or the other depending on what you’re doing.

In sports there’s handedness and footedness, like which foot you prefer to have in front on a skateboard (I ride goofy-foot even though I’m right-handed). I think the brain is deciding how to divvy up the visual demands between your eyes. Apparently there are visual skills that can be learned, and vision therapists can teach some people how to use their eyes better. I wish I knew how they do it because it’s very interesting to me, but I’m not keen to spend a lot of money on it (because I’m cheap!)


I knew that distance vision and close-up vision improve at different rates so your eyes would favor one over the other. I didn’t know that one individual eye would favor one activity over the other though. I thought my eye was going crazy lol. Thanks for the reply!

I don’t think this is a good thing. I remember reading somewhere that the same effect can happen if you patch for too long. I haven’t read much in this area though so don’t take my word for it.

That is disturbing. I’ve been wearing my differentials a lot away from the computer because this first pair of differentials has too much minus for left eye. It has been exciting to get out of the blurred world with gentle correction and see what blur horizon actually is.

How is your power for both eyes? Is your acuity about equal with the normalized you have now?

Currently, both my norms(1) and diffs(2) have -0.25 more SPH in the left eye. My left eye has no blur challenge and my right eye has too much blur challenge. Out of the three pairs I’ve used so far, none have given my left eye any blur challenge yet all of them have given my right eye too much blur challenge. Because of this I’m thinking of equalizing SPH so both eyes can have the same blur challenge and ideally improve at the same rate.