I've asked a doctor and he said that temporary blindness lasts 30 seconds to 2 minutes. Generally speaking, temporary blindness are caused by dizzy, eye irritation and foreign matters enter eyes. Here vertigo is the most commonly factor that irritate temporary blindness. Under this condition, temporary blindness may last for 1-2 minutes. Well, eye irritation may let eyes feel uncomfortable and watery eyes, then you 30 seconds or more. When something others enter your eyes, the first feeling of that must be hurt and unwell. This condition depends on the foreign itself. Now we should find out some ways to solute it. Well, first, when you get temporary blindness , close your eyes soon and no any rubbing or scratching on eyes; then apply warm towel on your eyes to reduce unwell feeling; finally drop some basic drops into your eyes to keep from eye strain and watery eyes which may caused by temporary blindness. If this still doesn't work or your temporary blindness exists all the way, go to see a doctor is your best choice.