The underling mechanism that contributes to acute acquired comitant esotropia（AACE）remains unclear; however, AACE is classified into several types based on the patient’s clinical presentation at the time of diagnosis. Although rare, AACE is known condition that has been described in the previous literature. An increasing number of case reports discuss AACE in recent time, and overuse of digital devices is suspected as a contributor. Currently, multicenter collaborative research is being performed by the Japanese Association for Strabismus and Amblyopia and the Japanese Association of Pediatric Ophthalmology to investigate the association between AACE and digital devices. Although uncommon, clinicians should be mindful that AACE may occasionally be accompanied by serious lesions such as brain tumors.

　There are two types of esotropia with myopia. The first is highly myopic strabismus that shows eyeball prolapse from the muscle cone on orbital magnetic resonance imaging（MRI）, and the other is an acquired concomitant esotropia in myopia that does not show eyeball dislocation. The orbital opening angle can be measured on the axial slice of orbital MRI. The orbital opening angle in patients with highly myopic strabismus is larger than that in patients with acquired concomitant esotropia in myopia. Thus, the orbital bone shapes and the pathogenic mechanism of these two types of esotropia are considered to be different.

　The causative factors for the onset of acquired concomitant esotropia in myopia remain unknown, yet the incidence of acquired concomitant esotropia has recently been increasing,especially in teenager and young adults. Acquired concomitant esotropia in myopia is a form that exhibits many similarities to acute acquired concomitant esotropia（AACE）, however, it onset is“insidious”rather than“acute”. A typical case of acquired concomitant esotropia in myopia initially presents with intermittent diplopia at only far distance. As it gradually progresses, the distance at which the patients show diplopia becomes shorter, eventually causing constant strabismus. Patients with acquired concomitant esotropia in myopia often have uncorrected or under-corrected refractive error, and it is speculated that the onset is caused by excessive neardistance work at close viewing distances and lifestyle habits that don’t focus on distance objects.

　Strabismus fixus convergens is characterized by restriction in both abduction and supraduction;the affected eye remains fixed in an esotropic and hypotropic position. Strabismus fixus with high myopia is specifically referred to as intractable strabismus.

　The retro-equatorial portion of the enlarged globe dislocates superotemporally from the muscle cone through the space between the superior and lateral rectus muscles. Magnetic resonance imaging（coronal view）reveals nasal displacement of the superior rectus, inferior displacement of the lateral rectus and dislocation of the globe out of the muscle cone. The Yokoyama procedure unites the superior and lateral rectus muscle bellies using a suture（15 mm）posterior to the muscle insertions. Restoration of the dislocated globe into the muscle cone improves ocular deviation and eliminates the mechanical restriction in ocular motility.

　Sagging eye syndrome is an age-related form of strabismus. The mechanism of onset involves age-related mechanical changes in the orbit, such as degeneration or disappearance of the orbital connective tissue pulley and malpositioning of the external rectus muscle. The criteria for diagnosis are older age, small-angle esotropia or cyclo-vertical strabismus, degeneration of the pulley, malpositioning of the lateral rectus muscle on orbital magnetic resonance imaging, no abduction limitation, normal saccadic eye movement, and age-related external ocular adnexal findings such as superior sulcus deformity, aponeurotic ptosis, or high lid crease as facial features. The criteria for exclusion are other ocular diseases, axial high myopia and brain disease. In epidemiological studies of strabismus in Japan, sagging eye syndrome accounts for approximately 23％of the cases of strabismus in the elderly, which is not a small proportion. Recent reports have shown that cases of strabismus are associated with both aging and axial high myopia, in addition to cases of esotropia with mechanical changes in the orbit without axial high myopia, and that orbital magnetic resonance imaging is useful for diagnosis and treatment selection.

　Crowded orbital syndrome（COS）presents with divergence insufficiency esotropia or vertical strabismus without obvious oculomotor disturbances and is a mild form of strabismus fixus. Cases showing high myopia without the development of this strabismus are found to involve a large orbital volume. COS is thought to be caused by a mismatch between eye volume and orbital volume, i.e., the eyes are large relative to the orbit. Moreover, enlargement of the eye is more likely to occur within the orbit. Conversely, if there is a discrepancy between the volume of the eyeball and that of the orbit, the disease can develop in cases with a small orbit, even in eyes with a normal ocular axis. Although the disease has been shown to be associated with pulley abnormalities, it occurs even at a young age without age-related changes in the pulley, suggesting that the narrowing of the orbit may be a trigger for ocular position abnormalities.

Aim: To define and characterize publications and citations in the field of optic nerve disorders.

Materials and methods: We accessed the Web of Science（Clarivate Analytics）online in September 2020; searched for articles with titles including optic neuritis, optic neuropathy, or optic atrophy published over a 50-year period from 1970 to 2019; and performed bibliometric and citation analysis of 5,230 relevant articles.

Results: The number of optic nerve disorder-related articles showed an increasing trend from about 10 yearly in the early 1970s to nearly 300 in the recent decades. Most studies originated from USA, followed by UK and Japan. The articles were published in about 700 different journals, led by Journal of Neuro-Ophthalmology and Neuro-Ophthalmology. The articles covered a diverse group of topics, including hereditary optic neuropathy, ischemic optic neuropathy, demyelinating optic neuropathy, toxic and metabolic optic neuropathy, compressive optic neuropathy, and autoimmune-associated optic neuropathy. Citation analyses of individual articles showed considerable variability among articles. The top 100 cited articles received more than 145 citations, led by Wallace et al.'s article on identification of mitochondrial mutation in Leber's hereditary optic neuropathy.

　A 77-year-old woman presented with an upper respiratory tract infection and observed diplopia and disequilibrium, 3 days later. Neurological examination revealed significant ophthalmoplegia,truncal and limb ataxia, and absent deep tendon reflexes. Serum anti-ganglioside antibody test results were positive（GQ1b-immunoglobulin［Ig］G, GT1a-IgG, GD1b-IgG, GT1b-IgG）, and we diagnosed the patient with Fisher syndrome（FS）. Intravenous immunoglobulin（IVIG）therapy led to gradual improvement in ataxia; however, ophthalmoplegia persisted. Ophthalmoplegia significantly improved after the administration of three courses of intravenous methylprednisolone（IVMP）, and her symptoms resolved 59 days after onset. Compared with the recovery period reported by previous studies, the duration of recovery from severe ophthalmoplegia was significantly shorter in our patient. IVMP may shorten the recovery period in patients with FS,who show persistent ophthalmoplegia despite IVIG therapy.

　We report three cases of accommodative spasm that caused refractive changes and myopia. The patients underwent measurement of cycloplegic refraction and were prescribed progressive power glasses, which were deemed effective for the accommodative spasm.

　In case 1, which involved a 7-year-old girl, the course of refraction, miosis, and esotropia at the onset of the accommodative spasm was recorded using a Spot Vision Screener（SVS）. The SVS was an effective tool for evaluating the state of the accommodative spasm and the effect of progressive power glasses. Cases 1 and 3, which involved a 10-year-old girl, were caused by psychogenic factors. During follow-up, we observed that the patients in cases 1 and 2, which involved an 8-yearold girl, discontinued the use of progressive power glasses, and the accommodative spasm recurred.

　Thus, we found that progressive power were effective in suppressing excessive accommodation in children with accommodative spasms.

　A 65-year-old woman developed inferior visual field defects and papilledema in the right and left eyes at two and eight months, respectively, after vinorelbine treatment for breast cancer. The visual acuities, intraocular pressures, and critical flicker frequencies for the right and left eyes were 1.0 and 0.4, 16 and 13 mmHg, and 38 and 13 Hz, respectively. Both eyes showed similar pupil sizes, but the left eye showed a relative afferent pupillary defect. Fundus photography showed right optic nerve atrophy and left inferior papilledema. Cerebral MRI showed no optic neuritis or inflammation due to blood collection, and the anti-aquaporin 4 antibody test yielded negative results. Although vinorelbine discontinuation was considered to prevent toxic optic neuropathy,the drug was effective for the breast cancer and was continued until December of year X＋1. The final visual acuities were 1.2 and 0.4 for the right and left eyes, respectively, indicating optic nerve atrophy and bilateral visual field disturbance. Vinorelbine was discontinued, but without an improvement in the optic neuropathy. Vinorelbine is a vinca alkaloid-based anticancer agent and microtubule inhibitor. Optic neuropathy has been previously associated with paclitaxel and docetaxel, which belong to the same class as vincristine. Thus, optic neuropathy can occur after vinorelbine treatment.

Purpose: We report the findings in two cases of optic neuropathy presenting as a rare complication induced by cisplatin（CDDP）and carboplatin（CBDCA）in reducing the side effects of CDDP.

Case 1: The patient was a 72-year-old male who visited our hospital complaining of a constricted visual field in both eyes 3 months after treatment with CBDCA and pemetrexed chemotherapy for malignant pleural mesothelioma. His visual acuity was（0.6）OD and（1.0）OS, and papilledema and disc hemorrhage were observed in both eyes. Relative afferent pupillary defect（RAPD）was present in the right eye, and a peripheral visual field defect excluding the central 15° was observed in both eyes. CBDCA-induced optic neuropathy was suspected, but chemotherapy was prioritized and continued from the first visit to 75 days later. His visual acuity was（0.7）OD and（0.9）OS, respectively, and the peripheral visual field defect persisted one year later.

Case 2: The patient was a 70-year-old male who experienced deterioration of vision 4 months after fluorouracil and CDDP chemotherapy for esophageal cancer and visited his doctor, who observed papilledema in both eyes. Visual acuity was（1.0）OD and（0.9）OS. The right eye showed RAPD and supra/nasal visual field defects. CDDP-induced optic neuropathy was suspected, so the chemotherapy was changed. After 137 days, the visual acuity of both eyes improved to（1.2）.

Conclusion: Case 2, in which CDDP was changed early, showed good visual prognosis. Although the prognosis of visual function is affected by the timing of discontinuation, the timing of the change should be based on the severity of the primary disease．