I have similar experience, but next day symphtoms dissapear.

@Zuzana, thanks for sharing your experience.

There is no substantive evidence of effects use of face shield in vision simply because the shield is non optical.

Temporal foggy vision is presented but not impaired

Thanks for elucidating @Carlvin and Rayan.

Yes It can impair,

1) Transparent sheild may become hazy due to breathing(exhalation), and

2)fiber material may not be that much transparent,

3) refractive surface may not be uniform

@Veena, your number 1 answer is quite impressive. I have observed that too. Thanks.

The face shield is curved instead of a flat surface, the curved surface act as a refractive lens, and distorted your vision by higher order aberration. Just like glasses with astigmatism. With prolonged wearing, your visual cortex is adapted to the distorted image, and self adjusted to match your propioception sense. Thus, when you took that off, you found the image is curved up.

This leads to the interesting question on how we perceive the environment we live. Imagine our visual input was upside down since birth, we may not understand gravity as we do

@ Sunny Chi Lik Au, thanks for this expert answer. I understand perfectly.

One can temporary have some discomfort, but not a prolonged impairment

Wearing for prolonged time can affect you and this requires you wearing glasses to correct the distances of the objects.