”Double vision”, is when only one object is seen as two, i.e. double vision. As shown below: If you notice double vision, you must first determine whether you have double vision when looking with both eyes or when looking with one eye. Binocular diplopia: Double vision in both eyes at the same time, but no double vision in one eye. Etiology: lesions in the extraocular muscles responsible for eye movements or in the nerves innervating the extraocular muscles, seen in: cranial trauma, ischemia, and occupancy; orbital fractures, orbital occupancy, orbital tumors, contusions or ischemia of the extraocular muscles; drug or alcohol intoxication, myasthenia gravis, diabetes, hyperthyroidism; external retinal detachment, orbital tumor removal, strabismus surgery, and postoperative cranial surgery. Monocular diplopia: blocking one eye and double vision when looking with one eye. Common causes: caused by diseases of the eye itself (seen in: irregularity of the corneal surface due to corneal scar or cone cornea, etc., uneven or subluxated lens clouding, multiple pupils due to trauma or surgery, upper eyelid swelling pressing on the eye), central nervous system diseases, etc. In addition, fraudulent blindness can also produce monocular diplopia. Suggestions: Since there are many causes of diplopia, the treatment principles and treatment measures vary for diplopia caused by different causes. Therefore, if there is double vision, it is recommended to go to the hospital for examination as soon as possible to clarify the cause so as not to delay the treatment.