Thanks for query.
Due to vaso vagal shock
plasma donors always fall down.
When volume of our blood becomes less due to plasma donation vaso vagal shock occurs in most of the cases thats why they leave you in supine position for 5-10 minute & offer you tea or coffee.
The spots in right eye 7 dizzy feeling is due to anxiety
So nothing to worry.
So don't worry you have choose a good way to serve society.Go for plasma donation next time it is a good habit & service to society.