I have a white dot on my pupil, which is in the middle of eye. Right in the middle The pupil. It is a spot in front of pupil it is in my left eye vision is bad. But my right eye has vision good

Sounds like you have a cataract building up. If it is that noticeable to you that you can actually see it you may want to have it removed. If you are having problems seeing out of that eye then definitely look into having it removed. There is something you could try to use for your cataract. I have been diagnosed with a cataract in my left eye but it is not noticeable to the naked eye. I tried an eye drop called Can-C and it seems to have cleared up my vision somewhat. It takes a few months to really work and dissolve the cataract but it's worth a try. You will have to buy it online as pharmacies don't carry it.