The exact etiology of FD is still unknown . FD is normally divided into three types: monostotic, polyostotic (accompanied by skin pigmentation such as coffee and milk stains and endocrine disorders) and McCune-Albright syndrome . According to the location to the lesion, the clinical manifestations are varies. Concerning FD that affects the skull, visual loss occurs acutely or chronically . Most frequently visual impairment of FD is seen due to optic canal stenosis or bone cyst formation [4, 5], but it can also occur secondary to spontaneous hemorrhage [4, 6], mucocele formation of the sinus [4, 5] and traction of the optic nerve caused by proptosis . Therefore, timely use of appropriate ways to remove the optic nerve compression and pull for the rescue of vision is very important.
When the optic nerve is oppressed by concurrent cystic degeneration or hemorrhage, which result in vision loss, an operation that decompresses this nerve, can be provided. Diah et al. reported 9 cases of cyst degeneration of craniofacial FD, 4 among them with visual disturbance. Surgery restored vision in two of the four patients, but two others were confirmed to have optic nerve compression and completely lost their vision . Singh et al. also reported a patient who had suffered from deterioration of vision in the left eye for 1.5 years. Postoperatively the patient improved cosmetically, but the patient’s vision recovered marginally . Reviewing the cases of acute vision loss from hours to weeks, the visual acuity of the patients recovered well after optic nerve decompression [3, 9,10,11,12]. However, patients with a gradual loss of vision over years are not able to get better visual acuity after optic nerve decompression [8, 13, 14].
As for the choice of surgical methods for optic nerve decompression, transcranial and transfacial approaches are classic and universal. Although endoscopic transnasal approaches are not used much, they have existed as early as 1991 . At present, the surgical methods of endoscopic transnasal approaches are becoming more and more skillful. Although, there is little literature on the use of nasal endoscope for optic nerve decompression for the treatment of other optic nerve diseases. There are a large number of literatures about using nasal endoscope to decompress optic nerve and treat traumatic optic neuropathy (TON). Meanwhile its safety has been fully proved. Compared with traditional methods, nasal endoscope takes the advantages of several aspects, such as decreasing morbidity, preservation of olfaction, rapid recovery time, more acceptable cosmetic results with no external scars and less operative stress in a patient who may have multisystem trauma and so on . DeKlotz’s group  observed 4 FD patients who had underwent optic nerve decompression through endoscopic transnasal approaches, the best corrected visual acuity of all patients was improved after operation, and the results of the early period showed that the visual impairment before operation was completely relieved or improved after operation. The endoscopic transnasal approach does play a new role in the treatment of these diseases, but the transcranial and transfacial approaches should not be phased out, because we still need more researches to prove much more additional benefits of transnasal endoscopic surgery.
Although follow-up observation is advocated in the treatment methods for FD, referring to the above data, it can be clearly found that surgical treatment, especially for optic nerve decompression, should be actively performed in acute vision loss caused by craniofacial fibrous dysplasia. Otherwise, the loss of vision will be irreversible. And we should carefully choose the approach of operation according to the patient's condition and wish. In this case, we firstly use navigation system to assist nasal endoscopic decompression surgery, and achieved a good result. The navigation system can help surgeons design surgical paths and accurately locate lesions, together with the surgeon's knowledge and experience, is a good guide to avoid surgical complications.