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.
1 The middle layer is the choroid. 2  The front of the choroid is the colored part of the eye called the iris. 3  In the center of the iris is a circular hole or opening called the pupil. 4  The inner layer is the retina, which lines the back two-thirds of the eyeball. The slight bulge in the sclera at the front of the eye is a clear, thin, dome-shaped tissue called the cornea. 2  See a picture of the cornea. 3  The middle layer is the choroid. 4  The front of the choroid is the colored part of the eye called the iris. 5  In the center of the iris is a circular hole or opening called the pupil.