I see sometimes invisible spots and i went to an eye doctor and he said my eyes were fine what could those transparent spots be ? floaters ?

Entoptics: You are seeing a normal phenomena - called 'flying corpuscles'. These are actually white cells passing through the capillary circulation at the back of your eye. You actually can view this way something microscopic which if lying on the table before you, you could not see. They are not floaters but are normal and a sign of good eye health.

Floaters: What you are actually seeing is a shadow cast by the natural "jelly" in the back of the eye, called vitreous humor. Sometimes it can look like strands of hair or comma shaped. If your doctor said that everything looked fine, then you likely don't have a retinal hole, tear, or detachment.