Paralysis of the facial muscle is due to the facial nerve pathology. Most of the time it is termed Bell’s palsy, which means that it is of unknown cause and it heals by itself in most of the cases.
When the facial palsy is permanent it would cause exposure of the eye, due to the inability to close the eye. As a result the eye would become severely dry which cause blurred vision, and in severe cases could cause loss of vision.
Treatment is usually surgical to enhance the closure of the eyelid and prevent dryness.