Ophthalmic silicone oil is a non-toxic, stable, colorless and transparent liquid used in ophthalmology mainly for patients with severe retinal detachment, ocular trauma, proliferative diabetic retinopathy and other diseases. It is an important intraocular filler in ophthalmic surgery, which has been used for nearly 50 years in ophthalmology, by combining vitrectomy with silicone oil filling to reset the retina and maintain normal intraocular pressure and shape. Silicone oil has the following characteristics: (1) The specific gravity of common ophthalmic silicone oil is 0.96-0.98, which is lighter than water. After injecting into the eye, it floats above the vitreous cavity, and through the buoyancy and surface tension of silicone oil, it produces a top pressure effect on the retina and promotes retinal adhesion. (2) Silicone oil has good light transmission, and light can pass normally after injection into the eye, which does not affect the postoperative observation of the fundus and is conducive to vision recovery. However, in crystalline eyes, injection of silicone oil can produce approximately +5.0D hyperopia, and in aphakic eyes, it can offset part of the aphakic refractive state. Therefore, patients who retain their own crystalline lens will experience a decrease in visual acuity after intraocular injection of silicone oil, whereas patients who have intraoperative combined removal of the crystalline lens have relatively good visual acuity, but after removal of the silicone oil, their visual acuity decreases instead due to crystal deficiency, which produces greater refractive problems and requires reimplantation of an IOL. (3) The viscosity of silicone oil is large, which can limit the freeing of inflammatory factors and proliferating cells in the postoperative eye to a certain extent, and effectively prevent the atrophy of the eye. Therefore, silicone oil is still a more ideal and difficult to replace vitreous filler. However, silicone oil injection into the vitreous cavity can result in a number of complications. Common complications include: (1) Cataract: After filling or removal of silicone oil, the intraocular environment changes significantly and affects crystal metabolism, which can lead to crystal clouding and require cataract removal IOL implantation when vision is affected. (2) Glaucoma. Excessive filling of silicone oil, emulsification of silicone oil or failure to perform strict prone position may result in symptoms such as elevated intraocular pressure, eye distension and pain, headache and vision loss, and secondary glaucoma, which requires the application of IOP-lowering drugs or surgical treatment, and the removal of silicone oil in severe patients. (3) Corneal degeneration and optic nerve atrophy, etc. As an oil-based substance, “emulsification” is another important characteristic of silicone oil. Long-term storage of silicone oil in the eye can lead to emulsification, i.e., from a complete silicone oil bubble to numerous small silicone oil droplets, which are dispersed on the surface of various tissues in the eye. Emulsification of silicone oil can lead to many of the complications mentioned above and can affect vision. Therefore, silicone oil must be removed through secondary surgery at the appropriate time. Most patients need to undergo silicone oil removal 3-6 months after surgery, but each patient needs to decide on the timing of oil removal based on a combination of factors such as retinal repositioning, degree of silicone oil emulsification, and systemic condition. After the injection of common silicone oil, there are strict position requirements for the patient. Most patients require prone position and a few patients require lateral position. Strict position maintenance can make the silicone oil produce better support to the detached retina and promote the recovery of the condition. If the prone position is not performed as requested by the physician, it will not only fail to provide adequate retinal support and retinal re-detachment will occur, but also lead to serious complications such as silicone oil entering the anterior chamber, increased intraocular pressure, and rapid cataract progression. Therefore, after silicone oil injection, the patient’s postural cooperation is of utmost importance. In addition, close observation and follow-up are important to detect various complications and provide relevant management in a timely manner. At present, for a small number of patients with lower retinal detachment and those who are too old to be in prone position, a new type of “heavy silicone oil” can be applied. Because its specific gravity is greater than that of water, it sinks beneath the vitreous and exerts parietal pressure on the lower and posterior retina, eliminating the need for a prone position. However, the use of heavy silicone oil is relatively limited and is only indicated for a small number of patients. Silicone oil into the anterior chamber: emulsified silicone oil droplets Complicated cataract Silicone oil injection in the prone position.