Myasthenia Gravis causes drooping eyelids (ptosis) because the immune system blocks communication between nerves and muscles, weakening the eye muscles that keep the eyelids lifted. This weakness worsens with activity (muscle fatigue), so symptoms like ptosis and double vision often become more noticeable later in the day or after prolonged use of the eyes. You should consult a doctor if you notice persistent eyelid drooping, double vision, or muscle weakness, as early diagnosis and treatment can help manage symptoms and prevent progression.