Soft contact lenses unstable vision

Vision differs with each blink, or restores to normal too long after blink.

How many experienced the same?

If I understand what you mean correctly, then yes, that is normal. I depends on what kind of lens you are wearing: Soft lenses have all sorts of properties and ways in which they are constructed. Some will glide better over your eye, some will feel more noticeable etc. - that is why one normally tests out a few different brands (optician gives the customer some test lenses from different companies) to test out which one feels most comfortable and works for you individually. I would not go as far as to say that that is “unstable vision” - the lens simply moves, has liquid underneath and on top of it etc and that is sometimes quite noticeable. In my long experience as lens-wearer this is actually a sign that your eyes are nice and moist. If the eyes are dry and the lens really sticks to the cornea one does not have what you probably mean by “unstable vision”.

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Fully agree with Jane.

When I started wearing contacts, I tested about 10 brands before settling on one. And actually most of them had the exact same BC / DIA / PWR values and still felt completely different. Like when you try the same size, similar type shoes on and only one pair feels comfortable and the other identical looking one does not.

Incorrectly fitted lenses can actually be pulled all the way up by the eyelid when blinking. (I just tested this first hand last year with coloured zero diopter contacts that I wanted to wear for a party but weren’t available in my usual contact brand.)
So apart from the fluid, vision can be disturbed by blinking, pulling the contacts all teh way up, then first looking through only the edge of the lenses before the centre of the lenses move back to the original position. But if this is the case, the brand should be changed and maybe BC and DIA, too.
If such lenses are worn too long, the eyes may get very sensitive by the constant “rubbing”, and I believe that is the reason behind many people getting completely intolerant to wearing contact lenses (completely or for longer period of time) after a couple of years - number of years depend if the lenses were completely ill-fitting or just sligthlyy ill-fitting.

I guess it’s the high power that introduces all that. -7 no cyl lenses, for example, have much less of that than -8.5 cyl -1.25 or -8 cyl -1.75, so I even don’t want to try/imagine how full correction e.g. -8 cyl -2.75 or normalized -7.5 cyl -2.75 would look like.

Contacts with cyl have a “weight” added at the bottom, so the lenses turn back to position to have the cyl correction at the right angle.
Normal contact lenses without cyl actually turn around on your eyes during the day but that’s not a problem as they have equal corrections all over the lenses.
Cyl ones also need to rotate back to position after blinking, or the cyl will correct at the wrong angle distorting image.

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