Depends. Cosmetic vs. Functional. If to change the eyelid fold or open the eyes more, may not change vision much, but if very droopy lids or hooding blocking vision preop, then removal of excess skin may improve peripheral vision.
Blepharoplasty. This is possible. A great deal depends on "why" one's vision is obstructed. An examination of the "visual" fields will help on this front. Often ptosis can impact one's vision. If there is a true vision obstruction, insurance companies may pay for this correction. This site will show you the results of asian eyelid surgery. http://www.drkulick.com/face-procedures-san-francisco/eyelid-surgery/
Sometimes. Blepharoplasty, when done to remove redundant skin blocking vision, should make vision better. When done for purely cosmetic purposes it shouldn't have much effect.
Depends. The answer is the same for non-asian eyes as well...If they eyelids were baggy enough to obstruct the vision, then a blepharoplasty will help. If the blepharoplasty is undertaken for cosmetic reasons (i.e. Non-functional) then it will not affect vision. To be clear, blepharoplasty only improves the "visual field, " it won't make blurry vision any more clear.
Sometimes. Older people (asian or not) whose peripheral vision is blocked by excess hanging skin can have their peripheral vision improved by removing this excess skin. This lets more light into the eye overall, as well, and patients will often report some sharpening of vision in forward view, as a nice bonus. No change in vision would be expected in a young asian person after a "double eyelid" operation.
Yes. If their vision was obstructed by their eyelid preoperatively.
Yes. Asian eyes have often very narrow opening therefor the field of vision and amount of light is limited. Blepharoplasty can improve both conditions without changing the asian shape of the eyes.