Slept with a sleep mask and now my vision is blurry! Is this normal?

It is likely that your eye mask was too tight on your head and caused too much pressure on your eye. If you apply pressure to your eye it will cause temporary blurred vision. In most cases, it won”t last very long, but it is not goof for your eyes. You may need to loosen your eye mask or get a different type that does not press directly on your eye.