The orbits are 2 four-pronged cones, located in the center of the cranial surface and protruding forward. It is susceptible to burst fracture by external force. In recent years, with the increase of traffic accidents and industrial trauma. Morbidity rate increased significantly. The most common complication is ocular entropion, followed by diplopia and vision loss. The treatment of orbital fracture involves both craniofacial reconstruction and visual function improvement. The treatment of orbital fractures involves both craniofacial reconstruction and improvement of visual function. The treatment of orbital wall burst fracture secondary to ocular enophthalmos is a difficult clinical problem. Due to unsatisfactory treatment results and surgical complications. Controversy exists in the choice of repair materials and treatment options. In our department, MEDPOR was used to repair patients with ocular entropion with satisfactory results. The incision was made parallel to the infraorbital rim 2 mm below the eyelash margin, about 3 cm long, and the skin and orbicularis oculi muscle were incised. The skin and orbicularis oculi muscle were incised. A traction suture was placed in the center of the lower eyelid margin. The orbicularis oculi muscle is separated from the lid by a subtle dissection to the inferior orbital rim. The periosteum was incised below the orbital rim along the inferior orbital rim, and the periosteum was peeled with a peeler along the inner inferior orbital wall in the direction of the orbital apex. After exposing the fracture site, the ophthalmic tissue embedded in the maxillary sinus was loosened and repositioned, and care was taken to protect the fracture fragments and sever the adhesion between the orbital periosteum and the orbital bone, which further exposed the infraorbital rim and orbital floor to make it a subperiosteal space, facilitating the repair of grafts on the orbital floor and the inner inferior wall. After adequate visualization of the orbital floor and return of the orbital tissue, Medpor lamellar implants are used to repair the orbital wall defect, and the size of the implant should be 2 mm larger than the circumference of the defect. The implant size should be 2 mm larger than the periphery of the defect. The implant can be used in conjunction with other surgical procedures. At the end of the operation, the incised orbital periosteum is carefully closed anteriorly to the infraorbital rim with 4-0 absorbable sutures to prevent the implant from shifting forward and protruding, and the lower eyelid margin incision is closed with interrupted sutures of 7-0 monofilament nylon sutures, and localized compression bandages are applied. Postoperatively, 20% mannitol (250 ml) and dexamethasone (10 mg) were administered intravenously once a day for 3 days to reduce the edema of the orbital contents and lower the intraorbital pressure. 2. The results of all the patients showed significant improvement in the postoperative eyeball invagination deformity, with normal eyeball movement, negative traction test of the infraorbital rectus muscle, and basically symmetrical eyelid fissure and ocular position with that of the healthy side. After 2 months to 5 years of follow-up, all patients showed that the degree of eyeball invagination was stabilized within 2 mm, and there was no recurrence of deformity and other complications. The results of the surgery were satisfactory. 3. Discussion 3.1 Anatomical characteristics of orbital region The orbital region is in the shape of a four-pronged cone, with the tip facing backward and the optic nerve tube passing through the cranial cavity. The bottom is forward, forming a quadrilateral orbital rim with an opening toward the face. The orbit is composed of facial bones and cranial bones, and the cranial bones form the upper wall. The facial bones form the medial, lateral and inferior walls of the orbit, and the four walls of the orbit vary in thickness, with the medial wall being the thinnest and the lateral wall the thickest. The extraocular muscles, except for the inferior oblique muscle, start from the orbital apex and end at the eyeball, so entering the orbital area along the orbital rim and the orbital wall generally does not damage the extraocular muscles or the important nerves or blood vessels of the eyeball. The intraorbital periosteum is in the form of a funnel-shaped sheath that encircles the orbital contents, and the intraorbital periosteum is only loosely attached to the orbital wall, where it continues with the dura mater at the supraorbital fissure. 3.2 Orbital wall fracture When the eyeball is subjected to a high-speed impact of an object with a size larger than the diameter of the orbit, the impact force acts on the thin orbital wall, resulting in a fracture of the orbital wall with the orbital rim intact, which is called an orbital fracture. Common causes include car accidents, sports injuries, boxing injuries, throwing objects and falls. Fractures of the medial and inferior walls are the most common. Coronal CT is better than horizontal for visualizing orbital wall changes and is a routine examination after orbital trauma. The adverse effects of orbital burst fractures include visual impairment, enophthalmos, and diplopia. Plastic surgery is performed primarily to improve the ocular entropion deformity as well as to correct diplopia. 3.3 Mechanisms and timing of surgery for orbital entropion: fracture of the orbital floor and the lateral wall of the orbit are displaced, and the volume of the orbital cavity is enlarged by bone; the bone wall is ruptured and defective, and the soft tissues of the orbit are herniated into the maxillary sinus and the sieve sinus, which reduces the volume of soft tissues of the orbit; and the extraocular muscles, muscle sheaths, and soft tissues are formed by scarring and contracture. Correction of entropion mainly involves filling of intraorbital implants to reduce the volume of the orbital cavity and prop the entropic eyeball out anteriorly. Early diagnosis and early surgery are generally emphasized. At the time of injury, the deformity may not be obvious due to the swelling of the eye, and with the subsidence of edema, the eyeball invagination will gradually appear. Generally, 2~3 weeks after orbital fracture is the best time for surgery, at this time, the soft tissues in the orbit and the fracture site have not been seriously adhered, and the soft tissue reset and repair of the orbital wall are easier. In patients with advanced intraocular deformity, although it can be improved as much as possible by delicate surgery, the result is relatively poor. 3. 4 Choice of Implants in the Fracture Area Autologous extracranial or iliac bone, plexiglass, silicone plates, hydroxyapatite, expanded polytetrafluoroethylene, and Medpor have been used to treat entropion deformity of the eye. Autologous bone grafts have the advantage of easy viability and fusion with the bony orbital wall. However, there are disadvantages such as damage to the donor area, graft resorption, and limited resources; silicone gel has poor histocompatibility and is susceptible to infection, displacement, or rejection after implantation; and hydroxyapatite is hard, poorly flexible, difficult to sculpt, and prone to fragmentation. Medpor is characterized by the following features: histocompatibility, low incidence of rejection and toxic side effects. Its ultra-microstructure is porous, after implantation into the body, the cells are easy to grow into, so as to make it fixed, but does not form a fiber capsule, can be removed in one piece. It has good plasticity, moderate hardness, good tensile strength, can be trimmed according to the required size, easy to operate, low absorption rate, and stable and long-lasting surgical effect. Medpo r implantation was used in this group of patients, and the postoperative effect was good. No obvious complications occurred, and the results were stable after follow-up. 3.5 Placement of the implant and correction of eyeball invagination The surgery is performed under the orbital periosteum, which will not damage the eyeball and the ocular muscles and vascular and neural tissues. The implant is placed under the periosteum just below the orbit or below the medial or lateral aspect of the eye, to a depth of the posterior wall of the eye. The implant should not be placed too deep, as it may compress the tissue at the orbital apex, which not only affects the movement of the eye, but also affects the vision. It is also not advisable to implant too superficially, as the periosteal elevation may push the eyeball to the opposite side, resulting in a contralateral displacement of the eyeball. In patients with significant inversion of the eyeball, increasing the width and depth of the implanted plate can improve the degree of inversion of the eyeball at the same time. If there is a bony defect in the infraorbital wall, the Medpor plate should be implanted larger than the extent of the defect. The thickness of the implant is usually 2 or more overlapping plates, which are contoured according to the curvature and anatomy of the orbital bone. Generally, a single layer is placed directly below the eyeball to cover the bone defect area, and the thickness of the implant can be increased medially and laterally in order to lift the sunken eyeball forward after adequate freeing and loosening. Adjustment of the eye position should be kept in mind at all times during implantation. In order to prevent undercorrection of the eyeball inversion deformity due to postoperative swelling and other factors, it is usually necessary to correct the eyeball inversion more than 1-2 mm on the contralateral side, and in severe eyeball inversion, it should be more than 2-3 mm during the operation.General anesthesia should be used as much as possible, so as to avoid injecting a lot of local anesthetic drugs, which will affect the estimation of implantation of the thickness of the Medpor. The implantation of Medpor should be performed under general anesthesia to avoid excessive local anesthetics, which may affect the estimated thickness of Medpor implantation. It should be noted that the intraorbital pressure should not be too high during implantation, and the pupil on the affected side may be temporarily dilated due to the disturbance of the eyeball by the intraoperative exploration. All patients were corrected according to the above criteria, and the postoperative results were satisfactory.