Thank you, Neuro-ophthalmologist Thomas Mizen, MD, Rush University Medical Center, for explaining MG vision issues to 65 Spring Meeting attendees on May 4, 2017!
You can see a short clip from Dr. Mizen’s presentation – or the full presentation – on our YouTube channel.
Here are highlights from Dr. Mizen’s presentation:
- In 15% of all patients symptoms and signs are confined to ocular muscles.
- Only half of patients with ocular myasthenia gravis have detectable muscle antibodies.
- Ptosis (drooping eyelids) and diplopia (double vision) are common initial symptoms, but the disease remains restricted to ocular muscles in only a minority of patients.
- Myasthenia gravis with Musk antibodies is not manifested as ocular myasthenia, whereas both acetylcholine receptor and LRP4 antibodies can be found in the ocular subgroup.
- Each eye is controlled by 6 muscles and 3 nerves. The coordination of eye movement occurs in the brain stem neural integrator controlling these nerves and muscles.
- When we sleep at night the eyes roll up. In the morning through the process of fusion the two images are brought together to form single binocular vision, seeing one image with two eyes. Throughout the day the eye movement control center maintains fusion to see one object in all positions of gaze
- Double vision, or diplopia, results when the two eyes are not working together. It can occur as a result of underaction of any of the 6 muscles.
- Double vision can vary throughout the day. It is worse with fatigue, less with rest.
- Variability of diplopia also makes a solution difficult. We seek a solution that works the majority of the time. It may require different glasses with different prism for different activities (for instance, one pair for distance, one pair for reading). Ocular symptoms may also respond to treatment with medication.
- In addition to the eye movements, the eyelid also may be involved with MG (ptosis). Ptosis usually responds to the same intervention as for double vision.