OBJECTIVE: To provide an objective measurement method for the neostigmine test in patients with myasthenia gravis ptosis and/or ocular motility disorders using a video ophthalmometry system. METHODS: A video ophthalmometry system was used to acquire and measure lid fissure size and abduction and adduction dewlap in patients before and after the neostigmine test, and to analyze the myasthenia gravis group and the control group. RESULTS: The lid fissure size in patients with MG group in plain view was (2.621±0.3759) mm in multiple measurements, (0.823±0.2661) mm in the control group with other neurological disorders and (0.853±0.2543) mm in the normal control group. the difference between the MG group and the group with other neurological disorders as well as the normal group was statistically significant (P < 0.05). CONCLUSION: In MG patients with extraocular muscle involvement, the video ophthalmometry system provides an objective measurement method for the neostigmine test.