Symptoms of MCNP may include: Weakness in one or more eye muscles Blurred vision that improves by closing either eye Double vision Pain in or around the eye (related to lack of blood flow to the covering of the brain), which commonly occurs at the onset of double vision Drooping eyelid (called ptosis) Enlarged pupil (rarely) If you are diagnosed with MCNP, it is very important to tell your doctor if you have new symptoms of double vision that appear after your diagnosis or if your double vision fails to resolve.