Neuromyelitis optica spectrum disorder（NMOSD）is an autoimmune disease that mainly affects the optic nerves and spinal cord. The pathomechanism of NMOSD is mainly related to the aquaporin-4（AQP4）antibody and complement-mediated astrocytopathy, which is different from classical demyelinating diseases, such as multiple sclerosis. In vivo and in vitro studies revealed the role of AQP4 antibody and complement-dependent cytotoxicity against astrocyte foot processes;this core mechanism is linked to the breakdown of the blood-brain barrier, tissue edema,orchestrated inflammatory responses, secondary demyelination, and axonal damage. The therapeutic options have now broadened and include monoclonal IgGs against molecules of complement and B cell lineage cells. Here we would like to focus mainly on the role of complement in disease mechanisms and the relevant therapeutic strategy in NMOSD.

　Neuromyelitis optica spectrum disorder（NMOSD）is an autoimmune disease associated with a pathogenic anti-aquaporin（AQP）-4 autoantibody. In particular, patients with NMOSD are frequently affected with severe relapses. Although standard immunotherapy, immunosuppressive agents, and corticosteroids can prevent acute attacks and maintain remission in most of patients, there is a strong need for alternative treatments in patients who are refractory to standard therapies. Notably, interleukin（IL）-6 exerts pleiotropic effects on immune cells, playing a critical role in NMOSD pathogenesis. Given this finding, satralizumab, a humanized monoclonal antibody IL-6, has been approved as an emerging preventive treatment for NMOSD in 2020.

　Limited therapeutic options are available for the management of patients with severe visual loss due to the acute phase of optic neuritis（ON）refractory to intravenous methylprednisolone（IVMP）administration.

　Regardless of the presence or absence of glial autoantibodies, blood purification therapy（BPT）, including plasmapheresis is considered in patients in whom IVMP is ineffective. Although BPT is increasingly used in steroid-resistant ON, its therapeutic efficacy and safety profile remain controversial. Moreover, BPT is associated with the risks of hypocalcemia and infection and is occasionally infeasible owing to the need for dialysis equipment and the service of a dialysis specialist.

　Intravenous immunoglobulin（IVIG）therapy is preferred because it can be administered without any special prerequisites, and ophthalmologists or neurologists can initiate treatment immediately（because prompt treatment is essential for effective management of steroid-resistant ON）. In this clinical review, we discuss all available articles that report current evidence to support IVIG administration during the acute phase of ON, including research in animal models, clinical trials using different regimens, and affirmative case series.

　The article also includes comprehensive commentaries on multicenter, double-blind, randomized, controlled trials of IVIG in Japanese patients with steroid-resistant ON. Based on these results, we conclude that IVIG benefits patients with steroid-resistant ON.

　Dural arteriovenous fistula（dAVF）can cause cerebral vein perfusion disorders and presents with various symptoms. We report a case of dAVF in a 72-year-old man whose visual function was maintained with early treatment. He became aware of transient blurred vision and vascular noise and was referred to our department by a local ophthalmologist for bilateral papillary swelling. His best-corrected visual acuity in both eyes at his first visit was 1.2. He had no abnormalities in either eye, except bilateral papillary swelling. Head magnetic resonance imaging（MRI）, magnetic resonance angiography（MRA）, and magnetic resonance venography（MRV）findings were suggestive of dAVF of the lateral and sigmoid sinuses. We referred him to the neurosurgery department and he was finally diagnosed with dAVF. Catheter treatment was performed 1 month after the first visit. Postoperatively, there was improvement in the transient blurred vision, vascular noise, and papillary swelling. To identify the cause of bilateral papillary swelling, it is necessary to look for intracranial space-occupying lesions but also intracranial hypertension due to perfusion disorders at an early stage using MRI and intracranial angiography approaches, such as MRA and MRV.

　We report a patient with tuberculum sellae meningioma whose formerly implanted multifocal intraocular lens（IOL）was replaced with a monofocal IOL after surgery. A 60-year-old woman presented to a nearby ophthalmologist for blurred vision and decreased visual acuity in the right eye, and she was diagnosed with posterior subcapsular cataract. Since the blurred vison in the right eye did not improve after surgery, she underwent replacement surgery with a monofocal IOL; however, there was no improvement even after the replacement with monofocal IOL. On her first visit to our hospital, the best corrected visual acuity（BVCA）was 0.8 and 1.5, and critical flicker frequency（CFF）was 12 Hz and 35 Hz in the right and left eye, respectively; relative afferent pupillary defect（RAPD）was present in the right eye. Central scotoma and superior-nasal vertical step in the right eye and superior-temporal vertical step in the left were detected using Goldmann perimetry, presenting a pattern of junction scotoma and left homonymous hemianopia. Thinning of the circumpapillary retinal nerve fiber layer in the temporal sector of the right eye and both in the temporal and nasal sectors in the left eye were revealed by optical coherence tomography. Magnetic resonance imaging showed a well-defined mass lesion in the upper sella turcica area, leading to a diagnosis of compressive optic neuropathy due to meningioma. After surgery, the BVCA was 1.5 and CFF was \_p33 Hz in the right eye; visual field abnormalities in both eyes showed significant improvement. In patients with unilateral progressive changes in visual function and ocular structure after cataract surgery, we should keep the possibility of pre-existing intracranial lesions in mind and take care when considering the clinical indications for multifocal IOL replacement.

　A 75-year-old man with a 1-month history of paroxysmal headache and 2-week history of decreased right vision and jaw pain presented to our hospital. The corrected vision at the initial diagnosis was 1.2 in the left eye and no light perception in the right eye. Relative afferent pupillary defect was present in the right eye, and the light reflex of the right eye was diminished. The right optic disc was slightly elevated and reddish. Giant cell arteritis was first suspected because the erythrocyte sedimentation rate was high, in addition to the presence of scalp tenderness, jaw claudication, and weight loss. He underwent steroid pulse therapy on the same day he presented to the hospital. The head computed tomography performed three days later revealed a soft tissue shadow with bone damage in the right sphenoid sinus. He underwent nasal endoscopic surgery because of suspected fungal infection. Based on the biopsy results, the patient was definitively diagnosed with invasive paranasal aspergillosis. Steroid treatment was stopped, and the antifungal agent voriconazole was started. It is challenging to differentiate invasive paranasal aspergillosis from vasculitis and other paranasal sinus diseases; however, cooperation among all departments is necessary to provide appropriate treatment.

　We report a case of Camurati-Engelmann disease（CED）with binocular papilledema.

　A 33-year-old man presented with a corrected visual acuity at the first visit of 1.0 and 1.2, intraocular pressure of 14 and 14 mmHg, and critical flicker frequency of 34 and 34 Hz in the right and left eye, respectively. Visual field examination found enlargement of the binocular Marriott blind spot and decreased sensitivity on the inferior nasal side of the right eye. Head MRI showed no abnormalities causing papilledema except for skull cortex thickening. One year after starting oral acetazolamide to reduce intracranial pressure, the corrected visual acuity was maintained at 1.2 in both eyes, but remarkable visual field impairment was observed. Since the optic disc swelling had not completely resolved, we decided that the deterioration of visual function could not be prevented and referred him to a specialized institution for surgical treatment. To differentiate papilledema, bone dysplasia diseases, such as CED, should be considered despite their rarity.

　In addition, this disease is progressive, and it might lead to future direct compression of the optic nerve and impairment of blood flow. If the papilledema does not improve following conservative treatment, surgical treatment should be considered.

Introduction: Carotid cavernous fistula（CCF）is a rare condition that refers to an abnormal connection between the cavernous sinus and carotid arteries. Indirect CCF mostly occurs in older female patients and can resolve spontaneously. External manual carotid compression（EMCC）is used for the conservative management in CCF, particularly indirect CCF.

Case Report: A 61-year-old female patient presented with proptosis, lagophthalmos, episcleral injection, pain, headache, redness of the left eye, and ophthalmoplegia since 2 weeks before admission. She was hypertensive without any history of trauma. Her left visual acuity on the Snellen chart was 0.3, with unremarkable contrast and color sensitivity. She had a corkscrew appearance on the conjunctiva and Grade I left relative afferent pupillary defect. Funduscopy examination revealed tortuosity of the blood vessels with optic disc swelling. Computed tomography angiography showed a type B CCF according to the Barrow Classification. Digital subtraction angiography（DSA）was planned, and the patient was instructed to perform EMCC while waiting for DSA. After 2 months, her condition improved.

Conclusion: Indirect-type CCF can occur spontaneously and can be a sight-threatening condition. Indirect CCF can spontaneously resolve with EMCC.