Symptoms depend on which muscles are affected. For example, when weakness affects muscles of the chest, people may have difficulty breathing. When weakness affects muscles that control the eyes, people may have double vision. Complete muscle weakness causes paralysis.
The choroid is the layer of blood vessels and connective tissue between the sclera (white of the eye) and retina. It is part of the uvea and supplies nutrients to the inner parts of the eye.
This, and the fibrous white sclera help to keep the shape of your eyeball. The blood vessels that run through the choroid carry food and oxygen to the cells of the eye. The retina lines the inside of the eyeball. This is the nerve layer of the eye. The cells of the retina react to light. They send messages to the brain through the optic nerve, making it possible for you to see.