The droopy eyelids are related to the eyes socket and the skin around the eyes. The vision is related to the visual system including visual nerves, and eyeball. The eyeball including wall and fibrous membrance, retina, aqueous fluid, crystalline lens, vitreous body. They are belong to different system. So I consider that the droopy eyelids would not affect the vision, except the upper eyelids drop to the lower eyelids to close the eyes totally. It will obscure the vision. If the pupil has not been hided, the people with droopy eyelids' vision will be the same with the normal people.
Yes, the droopy eyelid will affect your vision. The droopy eyelid may be caused by the dryness of the eyes which will make your eyes feel not comfortable. You will see things not that clear when your eyes are too dry. You could use some eyes drops to release this symptom. In addition, you could also use the oil essentials to make the eyes surrounding parts feel smooth and comfortable.