The orbital apical region contains the optic canal, supraorbital fissure and infraorbital fissure, with a small space but access to important vascular nerves, such as the optic nerve, ophthalmic artery, ciliary ganglion, general tendon ring of the extraocular muscles and innervated nerves, which are closely related to the visual and oculomotor functions. Surgery of lesions in the orbital apical region has traditionally been very challenging, and traditional surgical accesses are mainly transorbital as well as transcranial [1-2], etc. In recent years, with the development of endoscopic skull base techniques [3], transnasal endoscopic access has been reported for the management of lesions in the orbital region [4-7]. In this study, we retrospectively analyzed the surgical experience of 18 cases of endoscopic transnasal management of orbital apical lesions, so as to investigate the surgical strategy and indications for this approach. DATA AND METHODS 1. GENERAL DATA: Eighteen patients with proptosis and decreased visual acuity as the main symptoms of orbital apical zone occupying lesions who were admitted to our neurosurgery department from January 2009 to June 2013 were retrospectively analyzed. The symptoms were all monocular, 10 cases in the left eye and 8 cases in the right eye; 10 cases in males and 8 cases in females; ages ranged from 2 to 65 years, with a mean of 42, 8 years; the longest duration of disease was 12 months and the shortest was 7 days after injury. All patients were clearly examined by detailed ophthalmologic examination for visual acuity and ocular conditions and ocular lesions. 2, clinical manifestations: preoperative symptoms: 12 cases of decreased visual acuity, including 4 cases of intraorbital foreign body injury without light perception; 9 cases of protrusion of the eye, with a protrusion range of 2 mm to 18 mm compared with the healthy eye; 8 cases of eye movement disorders; 7 cases of pain in the affected eye; 5 cases of headache. 3. Imaging features: orbital CT and MRI were performed before and after surgery in all cases. The lesions were completely located in the orbit in 11 cases, including 4 cases of cavernous hemangioma and 5 cases of intraorbital foreign body and 2 cases of inflammatory pseudotumor, among which 1 case of cavernous hemangioma was located in the orbital opening of the optic nerve canal, 1 case of foreign body was located between the bone of the orbital wall and the orbital fascia at the base of the skull, and the remaining 9 cases were located in the orbital muscle cone, medial or inferior to the optic nerve, with a maximum tumor diameter of 50 px. 7 cases had lesions in the sinus region involving the optic nerve canal and the orbital apical region. The maximum diameter was 50px. The cysts of the frontal sinus, septal sinus and pterygoid sinus protruded into the orbit in 3 cases; the lesions of the cavernous sinus and pterygopalatine fossa involved the inner and lower walls of the orbit in 1 case each; and the abnormal proliferation of bone fibers at the skull base involved the orbital apex and the optic nerve canal in 1 case. The intraorbital foreign bodies were metal in 2 cases and vegetative foreign bodies in 4 cases. 1 case of vegetative foreign body penetrated one side of the orbit and the contralateral infraorbital fissure. The detailed intraorbital localization of the occupying lesion was clarified by imaging examination before surgery, and neuronavigation was applied intraoperatively in 12 cases. 4. Surgical methods: Karl Storz endoscope and skull base microsurgical instruments were used for the surgical instruments, and the intraoperative operation was based on 0° mirror. Nasal mucosal infiltration anesthesia was performed with 1% lidocaine + 0,01‰ epinephrine. All patients underwent general anesthesia with tracheal intubation and controlled intraoperative blood pressure reduction. After endoscopic transnasal resection of the hooked process and opening of the septal and pterygoid sinuses, the orbital cardboard was fully exposed, the orbital apical area was localized, and the inner wall of the orbit and the optic canal of the lateral wall of the pterygoid sinus were revealed. The site and extent of resection of the orbital wall were determined according to the preoperative imaging data, generally within a range of 50 px × 1 cm. The orbital fascia was incised and a small amount of excised adipose tissue was removed, and the view was expanded by pushing away the fat and internal rectus muscle with saline cotton. After resection of the lesion, the surgical cavity was flushed with antibiotics, the orbital fascia was repaired with artificial dura mater and the exfoliated orbital fat was pushed into the orbit, and the nasal cavity was filled with absorbable nanoabsorbent cotton to stop bleeding. Postoperatively, methylprednisolone 80 mg/day×3 days was administered, and glucocorticoids were used preoperatively and postoperatively in patients with inflammatory pseudotumors. Antibiotics were applied for 7 days postoperatively for intraorbital foreign bodies, and ocular symptoms were treated symptomatically. (1) cavernous hemangioma. 4 cases of cavernous hemangioma with diameters of 0.5 to 50 px were localized under navigation, and 1 case was located in the orbital orifice of the optic nerve canal with a diameter of 12.5 px. Because of the close relationship with the optic nerve, the ipsilateral pupillary reaction was observed while exposing the resection during surgery. The other three cases were located in the orbital apical region, which was relatively large in size. The local orbital fascia was elevated due to the occupying effect of the tumor, and after the orbital fascia was cut and the intraorbital fat was peeled off, soft and dark red masses of tumor tissue with clear borders were seen. (2) Intraorbital foreign body. 5 cases were completely located in the orbit. 3 cases used neuronavigation equipment and 1 case used intraoperative X-ray to locate the foreign body. In one case, the foreign body was an embedded foreign body at the skull base, which was a 150px-long branch passing through the bilateral nasal cavity, involving one side of the orbit and the other side of the infraorbital fissure, and was exposed and separated at both ends, then cut off in the nasal canal and removed in a smooth manner. (3) Inflammatory pseudotumor. 2 cases were located in the intraorbital orbital apical region, which was poorly defined and adhered to the surrounding fat and ocular muscle tissues, and the lesions were partially resected and the intraorbital wall and optic nerve canal were bony decompressed throughout. （In three cases, the orbital fascia was intact despite the obvious invasion of mucous cysts into the orbit, and the sinus cavity was opened and drained after complete removal of the cystic fluid. in one case, the cyst was opened and the inflammatory granulation tissue in the optic nerve canal and orbital apical region was removed. in one case, an epidermoid cyst and one case of neurofibroma invaded the orbital wall and infraorbital wall, respectively. The orbital bone was completely removed and the pressure on the orbital area was released. All 6 tumors and 3 cysts were removed, 6 intraorbital foreign bodies were removed at once, and 2 inflammatory pseudotumors and 1 osteochondroplasia were partially removed. Of the 12 patients with decreased vision before surgery, there were 6 cases with significantly improved vision and 6 cases with no change after surgery, 4 of which were foreign body injuries with no light perception immediately before surgery. The protrusion of the eye improved significantly in 8 cases, and in 1 patient with osteochondrodysplasia, the protrusion of the eye did not improve significantly due to extensive lesions. All of the preoperative eye movement disorders, endophthalmitis and ocular pain and headache symptoms were relieved. Five patients had pain on eye rotation and mild diplopia in the early postoperative period, all of which recovered in about 1 week. one patient had mild postoperative entropion of the eye. all 18 cases were followed up for 3 months to 4 years, with no complications related to surgery. one case of inflammatory pseudotumor recurred after 2 years, and was resected again transcranially, and is now being followed up. Discussion Occupied lesions in the orbital apical region are usually tumors and foreign bodies. Foreign bodies are mostly diagnosed, while tumors include inflammatory pseudotumors, hemangiomas, epidermoid cysts, and malignant tumors [8], and surgical resection is still the main method of treating occupying lesions in the orbital apical region. Since Kennedy et al [9] reported the first case of transnasal endoscopic decompression of inferior orbital wall tumor, transnasal endoscopic orbital tumor surgery has attracted more and more attention. Xu G et al [5] systematically introduced endoscopic transnasal orbital surgery in 2002. In terms of anatomical and operative features [10], the transnasal route into the orbit is simple, and the indications for transnasal surgery should be suitable for tumors outside the nasal lateral muscle cone or medial to the optic nerve. Therefore, the location of the lesion in relation to the optic nerve and ocular muscles is the most important basis for surgical access selection. Referring to the classification by Darsant [11], we classified orbital lesions into four categories based on their relationship to the orbit and muscle cones: extra-orbital fascial lesions, suborbital fascial extra-muscular cone lesions, intra-muscular cone lesions, and intra-optic nerve canal lesions. In contrast, intraosseous cone and intraoptic canal lesions are more difficult to manage because of their close neuromuscular relationship and the obscuration of intraorbital fat. In our group, one cavernous hemangioma was located subdural to the orbital opening of the optic nerve canal, and three cavernous hemangiomas and five foreign bodies were located medial to the optic nerve within the muscle cone, and complete resection of the lesions was accomplished through this approach. Therefore, lesions located medially to the optic nerve near the nasal cavity are suitable for this approach. The nature, size, extent, texture, and degree of adhesion to surrounding structures are also key factors in the selection of the surgical approach and in determining the surgical outcome. This approach is not recommended for larger malignant lesions with heavy adhesions because of the limited exposure and difficulty of radical resection. In contrast, lesions that are more limited, soft and well-defined, such as cavernous hemangiomas, are suitable for resection by this approach. Because of the complex anatomy of the orbital apical region, the small operating space, and the obstruction of intraorbital adipose tissue, finding and revealing the lesion is the primary problem in surgical resection. In addition to familiarity with the anatomy of the orbital cranial floor area, the application of neuronavigation, intraoperative ultrasound, and X imaging techniques helps in the localization of the lesion and the identification of important anatomical structures [12]. Excessive removal of orbital fat and injury to the medial rectus muscle during surgery can cause entropion and impaired movement of the eye. It has been reported [13] that the medial rectus muscle was retracted on one side with a thick wire to expand the exposure. Our experience is that for lesions within the muscle cone, it is most convenient to expose the orbital fascia and fat along the gap between the medial rectus muscle and the inferior rectus muscle, and the orbital fat can be removed in moderation, but the medial rectus muscle is not easily retracted excessively, otherwise muscle edema will make the exposure more difficult, and postoperative damage to the medial rectus muscle may cause ocular The eye may become impaired after surgery due to damage to the internal rectus muscle. For cavernous hemangioma located in the muscle cone, small gauze or cotton can be used to push the fat and internal rectus muscle away from the tumor, and sharp separation along the edge of the tumor while gently pulling the tumor to the nasal side is an effective method to reduce intraorbital neurovascular injury. For intraorbital foreign body, there are mostly inflammatory tissues wrapped around it. Most of the metallic foreign bodies have smooth surfaces and are generally not difficult to remove. In contrast, for larger vegetative foreign bodies with rough surfaces, removal should follow the direction of orbital travel to minimize the activity of the foreign body that may cause injury to the surrounding neurovascular. The intraoperative operation of separating and removing lesions in the orbital apical region requires at least two instruments, and the endoscopic operating technique and cooperative proficiency of the operator and assistant are also decisive factors for the success of the operation in a narrow area with limited operating space.Tsirbas [14] reported that the posterior nasal septum was incised intraoperatively, and the assistant entered the instruments from the contralateral nasal cavity to assist in the operation. In our opinion, the operation of the orbital apical region from a single nostril is possible with skilled endoscopic technique, cooperation, appropriate access selection, and the so-called “four-handed operation” in which the operator and the assistant apply three instruments and the endoscope simultaneously with both hands [15]. Although no serious complications related to the procedure were observed in this group of cases, the number of cases and surgical experience needs to be further accumulated because of the short time of implementation. It is believed that with the development of technology, especially the availability of intraoperative electrophysiological monitoring of the optic nerve and oculomotor nerve, this type of surgery will become more and more mature.