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I just started wearing glasses to correct my myopia today. I have -0.25 spherical and cylindrical power in my right eye and -0.5 spherical and -0.25 cylindrical in the left eye. Everytime I look at the ground, it looks tilted. The left hand side of the ground seems closer than the right. Why is this happening?

Is it because each lens has a different image distance and the brain not being used to these glasses yet, makes this mistake while mixing the image from both eyes together? Or is this something related to the glasses themselves and will persist?

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    $\begingroup$ Aman, your correction isn't much, but there is one thing that your eye doctor needs to check. The center of the lens MUST be centered on your pupil, ESPECIALLY at higher corrective powers. If this isn't the case, the lens will correct your vision, but it will also introduce a "prism" effect, and distort what you are seeing. Have your eye doctor do the correct measurements and confirm your pupilary distance for each eye, then confirm that the lenses are appropriately mounted in the eyeglass frames. $\endgroup$ Nov 4, 2018 at 15:44
  • $\begingroup$ As David mentioned, this can be indicative of poorly-mounted lenses, but you should also keep in mind that this kind of disorientation is completely natural in first-time eyeglasses users and it tends to go away in a few days as your brain learns to compensate. The discomfort should have dissipated by now (and if it hasn't, return to the doctor ASAP) but it's still worth double-checking the lens placement as indicated by David. $\endgroup$ Nov 8, 2018 at 15:33
  • $\begingroup$ Thanks the disorientation has gone down quite a bit now. Can you explain the reason behind this initial disorientation (assuming the lenses are properly mounted)? Also, how can poor mounting cause this effect? $\endgroup$ Nov 8, 2018 at 16:38

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A cylindrical shape error in your eyes' lenses will tilt your horizon, but your brain gets used to that over time and your horizon seems level to you. When you put on the corrective lenses, this upsets the accommodation that your brain had learned to use and now the horizon seems tilted the other way. This too will go away with time.

As an example of how your brain can relearn the mapping of your visual field, you can put on prismatic glasses that flip your visual field upside down and in a matter of weeks, your brain will learn how to flip the image around so you can safely walk down the street even though you are seeing things upside-down. Then if you take those glasses off, everything looks upside down to you even though it isn't and it takes time for your brain to unlearn what you taught it with those glasses.

As an aside, the actual image of your visual field as projected onto your retina by the lens in your eye is upside down and reversed left-for-right, but the image as mapped into your perception of the world by the visual cortex and the nerve pathways between your retinae and the brain sort all of that out for you automatically.

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