What Is Ocular Myasthenia Gravis?

Myasthenia gravis is an autoimmune disease in which neuromuscular junction sites have transmission problems. Ocular myasthenia gravis (oMG) refers to the symptoms of myasthenia gravis confined to the extraocular muscles. Ocular myasthenia gravis can start at any age, and the relative peak incidence is <10 years old children and> 40 years old men. > 50% of MG patients start with ocular myasthenia gravis, of which 10% -20% can heal themselves, 20% -30% are always limited to extraocular muscles, and the remaining 50% -70% are extremely large Most (> 80%) may develop generalized myasthenia gravis (gMG) within 2 years of onset.

Myasthenia gravis

Myasthenia gravis is a

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Patients with the disease have mild eye movements and are mostly asymmetric

1. Droopy eyelid is a common first symptom, accounting for about 86%. It is better to get up in the morning and to get worse in the afternoon or evening. Generally, the onset of the disease occurs at first glance. After a period of time, the other eye may also develop. In severe cases, drooping of the upper eyelid occurs, but the degree may vary. Myasthenia gravis ptosis often manifests as follows:

(1) Eyelid weakness: When the patient blinks multiple times, the muscle activity gradually decreases, the upper eyelids sag, and the eyelid fissures become smaller.

(2) Cogan's eyelid tremor sign: For patients with drooping upper eyelid, first let them stare downward, then let them quickly stare forward. At this time, the upper eyelid briefly contracts upward, and then returns to the original upper eyelid Saggy position.

(3) Osber squinting sign: make the patient lightly close the eyes, and after 1 to 2 seconds, the eyelid suture is slightly widened and widened, exposing the lower sclera and showing squinting status. This is because of orbicularis muscle fatigue.

(4) Persistent gaze fatigue: When the patient's eyes are turned to the right and left, the eyes start to be more coordinated. If you continue to look at the side, the rotation of one eye slowly lags behind and tends to return to the first eye position. This indicates a lesion in the muscle-nerve junction.

2. Upper eyelid retraction Withdrawal of the upper eyelid with myasthenia gravis is uncommon and mostly temporary. It usually occurs after a long upward gaze and lasts only a few seconds. Due to the presence of upper eyelid withdrawal, misdiagnosis can easily occur. Puklin reported that three patients with myasthenia gravis showed symptoms of upper eyelid withdrawal.
3. At the same time that eye movement disorders and ptosis occur, eye movement disorders and diplopia often occur, accounting for about 67%. Among them, there are many obstacles, followed by medial rectus paralysis. Occurs on one or both sides, and can range from a single ophthalmoplegia to a total ophthalmoplegia.

4. Pupil dyskinesia Use infrared electronic pupil meter to measure pupils' response to light. The speed of pupil contraction is low. After intravenous injection of Teng Xilong, it shows a transient recovery.

5. Convergence and adjustment abnormalities In addition to eye movements in the same direction, convergence and adjustment disorders may also occur. The involvement of extraocular muscles in patients with myasthenia gravis is well known, but the involvement of intraocular muscles has not been recognized. Manson performed a near-point measurement of nine patients with myasthenia gravis, and eight of them shortened the short-distance by 8 to 15 cm after intravenous injection of anticholinesterase drugs. Patients with myasthenia gravis have more severe visual impairment and generally do not feel abnormal near vision. Therefore, it is pointed out that the regulation disorder is more common in patients with myasthenia gravis. The contractile smooth muscle in the ciliary body is dominated by the rich and refined autonomic nervous system. This nerve is also violated in patients with myasthenia gravis, and it is not limited to the striated muscle.