The purpose of the study is to testify the efficacy of treating trochlear nerve palsy with ocular electroacupuncture or ocular acupuncture, and to compare the efficacy between these two interventions.

The purpose of the study is to testify whether ocular electroacupuncture or ocular acupuncture is effective for trochlear nerve palsy (TNP), through treating TNP patient for 6 weeks, using self-invented acupoints according to anatomy of extraocular muscles innervated by trochlear nerve, and using sham acupuncture as controlled group, and try to provide clinical evidence for promoting these new techniques.

Inclusion criteria;

1. patient with confirmed diagnosis of trochlear nerve palsy made by neurologist or ophthalmologist;
2. patient in stable condition after treatment for primary disease;
3. age between 18 to 80 years old without gender limitation;
4. haven't received acupuncture intervention for TNP before;
5. patient with conscious, willing to cooperate and voluntarily agreed to participate and signed informed consent forms.

Exclusion criteria:

1. those with other diagnosed medical conditions known to contribute to TNP symptoms, such as thyroid disease, myasthenia gravis, mitochondrial myopathy, congenital strabismus or received strabismus surgery;
2. those with color blindness, dyschromatopsia or abnormal retinal correspondence couldn't complete computerized diplopia test;
3. those with serious medical conditions that might limit their participation;
4. those with eye or other location with serious infections;
5. women who had a positive pregnancy test or who were planning to become pregnant during the study period;
6. those with bleeding tendency, blood coagulation dysfunction or taken anticoagulant drugs;
7. who had participate in other clinical trials, which may affect the results.