Papilledema is defined as optic disc edema secondary to increased intracranial pressure. Papilledema is an important clinical finding as it is typically a warning sign of life-threatening conditions, such as a brain tumor, meningitis, or obstructive hydrocephalus. Currently, optical coherence tomography is widely used to quantitatively evaluate the time course of changes in optic disc edema by measuring the thickness of the circumpapillary retinal nerve fiber layer. Papilledema is usually asymptomatic, and the enlargement of the blind spot is its only manifestation in the acute stage. However, severe papilledema accompanied by serous retinal detachment, retinal hemorrhage, retinal exudates, and vitreous hemorrhage can result in decreased visual acuity. Chronic papilledema leads to optic disc atrophy and irreversible visual impairment.

　The pathogenesis of glaucomatous optic neuropathy, especially normal-tension glaucoma, remains controversial. A potent and attractive hypothesis is that the pressure gradient around the lamina cribrosa（translaminar pressure difference）can cause glaucomatous neuropathy. Most clinical studies have reported that normal-tension glaucoma is associated with low cerebrospinal fluid pressure（CSFp）, whereas several other studies have reported the contrary. All these studies were limited to a small number of participants, and the study protocols were not standardized. Therefore, a large-scale clinical study with a non-invasive method of measuring cerebrospinal fluid pressure is required.

　Several animal experiments for examining glaucomatous neuropathy caused by lowering cerebrospinal fluid pressure have been conducted. The results from these suggested three mechanisms described below: 1）a pressure gradient between CSFp and intraocular pressure at the cribriform plate could deform the structure of the cribriform plate, leading to the stagnation of axonal flow, 2）low CSFp could directly stagnate axonal flow with chemical or mechanical signal transduction, and 3）disruption in the clearance of toxic substances with a failure of the glymphatic system（lymph duct-like structure consisting of glial cells to excrete CSF outside the brain）due to the pressure gradient within the optic nerve pathway could induce cell death or axonopathy of retinal ganglion. These animal studies are limited in that the structure of the cribriform plate in rodents is immature compared to that in humans, and almost all of these studies involved an acutely lowering cerebrospinal fluid pressure model. However, we could observe the limited but obvious results of retinal ganglion cells’ axonopathy induced by decreasing cerebrospinal fluid volume, thus lowering its pressure. We could utilize these animal models for elucidating the molecular mechanism of glaucomatous neuropathy caused by low cerebrospinal fluid pressure, although well-elaborated animal models including chronic low cerebrospinal fluid pressure models also need to be developed.

　Intraocular hemorrhage is known to occur following acute intracranial hypertension; however, its etiology remains unknown. In the first session of this presentation, I will discuss the clinical characteristics of disorders that result in acute intracranial hypertension and describe cases of vitreous hemorrhage associated with acute intracranial hypertension. The most popular hypothesis accepted currently is that acute intracranial hypertension leads to rapid effusion of cerebrospinal fluid into the optic nerve sheath and that optic nerve sheath dilatation mechanically compresses the central retinal vein, and venous hypertension precipitates rupture of thin retinal vessels. Furthermore, the difference in the translaminar pressure gradient between intraocular and intracranial pressures produces papilledema in patients with an abnormal gradient.

　In the latter half of the presentation, I will describe Terson syndrome, which is characterized by intraocular hemorrhage accompanied by acute intracranial hypertension. Following are the possible pathophysiological mechanisms underlying Terson syndrome:（a）Vitreous hemorrhage secondary to acute intracranial hypertension may be attributed to the rupture of retinal capillary vessels following an acute increase in the pressure of the central retinal vein.（b）Arterial blood from the subarachnoid hemorrhage enters the vitreous space directly via the intervaginal space around the optic nerve, following penetration of the lamina cribrosa of the sclera. In a recent study, we reported that despite vitreous hemorrhage, patients with Terson syndrome do not show hemorrhage in the posterior precortical vitreous pocket. This finding may be clinically relevant and offer new insights into the pathophysiological mechanism underlying vitreous hemorrhage in Terson syndrome.

　The symptoms of cerebrospinal fluid leakage include headache, neck pain, dizziness, tinnitus, visual disturbance, nausea, malaise, and fatigue. Many patients also present to the ophthalmologist with symptoms such as eye pain, inability to focus, monocular diplopia, diplopia, decreased visual acuity, photophobia, and visual field disturbance. Ocular findings include convergence spasm, unexplained visual acuity and visual field disturbance, and concentric contraction; however, in several cases no ophthalmologic abnormality is found. In this article, we present four cases of cerebrospinal fluid leakage after ophthalmologic examination. It is necessary to pay attention to symptoms other than ocular findings, check the history of accidents and past trauma, and refer the patient to a specialist if cerebrospinal fluid leakage is suspected.

　Uhthoff’s phenomenon is characterized by visual impairment as body temperature increases. However, there has been no report regarding the association of Uhthoff’s phenomenon with ocular blood flow. Thus, we report the measurement of optic nerve blood flow before and after treadmill loading in a suspected case of optic neuritis using laser speckle flowgraphy（LSFG）.

　A 25-year-old woman noticed temporary impairment of her right eye after exercising and bathing, 1 month ago. Her visual acuity, visual field, visual evoked potential（VEP）, and optic disc blood flow were measured before and after treadmill loading, considering Uhthoff’s phenomenon. The above parameters were measured again at the time of phenomenon disappearance, 1 year later. While Uhthoff’s phenomenon, visual field abnormalities, and VEP delay were observed, there was no change in the optic disc blood flow before and after exercise. In addition, no change was observed in her visual field, VEP, and optic disc blood flow, before and after a vigorous exercise stress at the time of disappearance of subjective symptoms. In this case, optic disc blood flow was not associated with changes in visual acuity or visual field during the acute phase, suggesting that there is no clear association between Uhthoff’s phenomenon and blood flow.

　We report a case of fluctuating ptosis and extraocular palsy in all directions, with thickening of the inferior rectus muscle, in the left eye. A 47-years-old woman presented to our hospital with the chief complaint of left eyelid ptosis and diplopia. At the time of the first visit, ptosis of the eyelid, external superior strabismus, and eye movement disorder in all directions were observed in the left eye. A head MRI scan showed high intensity signals in the extraocular and the levator palpebrae superioris muscles of the left eye, and thickening of the inferior rectus muscle. A diagnosis of idiopathic ophthalmomyositis of the left eye was made, and the patient was followed up. Subsequently, ptosis of the left eye recurred, but steroid treatment was not effective.

　The present case was atypical for idiopathic ophthalmomyitis, and resistance to steroid therapy suggested the possibility of existence of another pathology.

　A 69-year-old woman suffering from headache, eventually followed by conjunctival hyperemia and proptosis of the right eye visited an ophthalmologist. Brain magnetic resonance imaging（MRI）revealed only extraocular muscle swelling; thus, ocular myositis was suspected and treated with oral prednisolone. Subsequently, the patient was admitted to our hospital because of poor clinical improvement. Initial neuro-ophthalmic testing revealed a visual acuity of 0.7 in the right eye and 1.2 in the left eye. A relative afferent pupillary defect in the right eye was noted along with mild restriction of elevation, abduction, and adduction. Furthermore, dilated and tortuous conjunctival vessels, conjunctival hyperemia, and proptosis were observed. Subsequent fundus examination revealed tortuous retinal veins and retinal hemorrhage around the veins. Contrast-enhanced MRI and magnetic resonance angiography（MRA）showed neither obvious arteriovenous fistulas nor abnormal blood vessels but revealed extraocular muscle swelling and proptosis. Although steroid pulse therapy was administered for the compressive optic neuropathy, the ocular findings did not improve. On the basis of ocular findings, an arteriovenous fistula was highly suspected; therefore, cerebral angiography was performed, revealing a dural arteriovenous fistula in the right cavernous sinus. Endovascular coil embolization was performed, leading to an immediate improvement in the patient’s symptoms and ocular findings. Arteriovenous fistulas present with various clinical manifestations; therefore, accurate diagnosis becomes difficult in cases lacking distinct MRI and MRA findings. In cases where an arteriovenous fistula is suspected on the basis of clinical findings, cerebral angiography should be actively considered in consultation with a neurosurgeon, even if the fistula is not detected on MRI or MRA.

　The patient was a 51-year-old man who complained of subacute diplopia and developed right eyelid ptosis one month later. Thyroid-associated ophthalmopathy（TAO）due to hyperthyroidism associated with myasthenia gravis（MG）was suspected based on a blood test and MRI. Methylprednisolone pulse therapy improved diplopia; however, right eyelid ptosis and the eye movement disorder persisted. After the second pulse therapy, improvement of the right eyelid ptosis was observed; however, limited eye movement fluctuated daily. It was difficult to accurately determine which disease was predominant and how effective treatment was for TAO and MG. However, it may be possible to evaluate the degree of improvement using characteristics and MRI findings.