Asymmetry of Bell’s phenomenon in both eyes is one of the symptoms of monocular double supination palsy. Monocular double elevator paralysis is characterized by asymmetry of Bell’s phenomenon in both eyes, which is often poor or absent in the affected eye. Double elevator paralysis refers to the simultaneous paralysis of the superior rectus and inferior oblique muscles in one eye. The clinical presentation is a downward strabismus in the affected eye, mostly combined with horizontal strabismus and ptosis. This ptosis is mostly pseudo or mixed and can be easily misdiagnosed as congenital ptosis. Tests for asymmetry of the bell phenomenon in both eyes: 1. CT examination of the eye and orbital area CT examination of the eye and orbital area is a method of examining the eye and orbital area by CT. CT scan provides a high-resolution, cross-sectional image and grayscale image of the eye, which uses X-rays as an energy source to display images of the body’s dimensions. CT is now very popular, thus providing a superior method of examination for the diagnosis of ophthalmic diseases. However, for various reasons, there are still many problems in CT analysis and diagnosis of ocular lesions. Ultrasound is superior to CT in the diagnosis of intraocular diseases, while CT is superior to ultrasound in the diagnosis of orbital lesions. In this article, we discuss some problems on CT diagnosis of orbital lesions and introduce the basic knowledge of CT related to diagnosis, which is very important for comprehensive analysis of ocular CT films. 2. Ocular functional examinations Ocular functional examinations include visual field, visual acuity. The examination of vision. Taken together, all examinations are important for the examination of ocular function. The visual acuity table is hung on the wall with sufficient fluorescent lighting or natural light, the visual acuity table is 5m away from the person being examined, and the visual scale on the 10th line of the table should be approximately equal to the height of the examined eye when looking forward horizontally, if the distance in the examination room does not meet the standard distance, a plane mirror can be placed at 2.5m opposite the visual acuity table, and the patient sits under the visual acuity table and observes from inside the mirror. 3.Ophthalmic examination The general examination of the eye, including the eye appendages and the examination of the anterior segment of the eye. The main purpose is to see the visual function of the macula. Generally, people think that normal vision means being able to see 1.5 or 1.0 in the visual acuity table, but in fact the standard of checking whether the vision is normal or not is: whether the vision can reach the standard after correction, i.e. whether the vision can reach the standard after optometry and glasses.