The management of optic neuropathy is fundamental to neuro-ophthalmic practice. Following the invention of the ophthalmoscope, clinicians, for a century or more, relied upon fundus examination in the evaluation of optic neuropathy. However, the advent of optical coherence tomography, based on the principle of backscattering of light and interferometry, has revolutionized the analysis of optic nerve and retinal disorders. Optical coherence tomography has proven of particular value in the measurement, at the micron level, of the peripapillary retinal nerve fibre layer and the ganglion cell layer. These measurements have proven critical in the differential diagnosis and monitoring of optic neuropathy. Specifically, thinning of the peripapillary nerve fibre layer provides evidence of axonal loss affecting any sector of the optic nerve. Thinning of the macular ganglion cell layer, on the other hand, shows a more precise correlation with visual deficits due to retrograde degeneration following optic nerve damage, although limited to central retina. In daily practise, optical coherence tomography is of great value in assessing the diagnosis, prognosis and response to treatment in optic neuropathy. Particular advances have been made, for example, in the assessment of optic neuritis, papilloedema and chiasmal compression which have translated to everyday practice. As with any other imaging technology the clinician must have a clear understanding of acquisition artefacts. A further issue is the relatively limited normative database in sub-populations such as the young and individuals with a refractive error > + 5 or < -5 dioptres.

UNASSIGNED: The clinical features of posterior cortical atrophy (PCA), a rare condition often caused by Alzheimer\'s disease, have been recently defined, while little is known about its neurophysiological correlates.
UNASSIGNED: To describe neurophysiological alterations of the visual pathway as assessed using visual field test (VF), visual evoked potentials (VEP), and electroretinogram (ERG) in PCA patients.
UNASSIGNED: Studies reporting VF, VEPs, and ERG in PCA patients were selected according PRISMA method. Of the 323 articles that emerged from the literature, 17 included the outcomes of interest. To these data, we added those derived from a patient cohort enrolled at our clinic.
UNASSIGNED: The literature review included 140 patients, half of them (50%) presented with homonymous hemianopia or quadrantanopia. VEPs were available in 4 patients (2 normal findings, 1 decreased amplitude, and 1 increased latency) and ERG in 3 patients (substantially normal findings). Our case series included 6 patients, presenting with homonymous lateral hemianopia in 50% and contralateral cortical atrophy. VEPs showed normal amplitude in 66-83% according to the stimulation check, and increased latency in 67% in absence of myelin damage on MRI. Latency was increased in both eyes in 50% and only on one side in the other 50%. Such alterations were observed in patients with more severe and symmetric atrophy. ERG showed normal findings.
UNASSIGNED: Neurophysiological investigations of the visual pathway in PCA are almost absent in literature. Alterations involve both amplitude and latency and can be also monocular. A multiple-point involvement of the optical pathway can be hypothesized.

Flash visual evoked potentials (fVEPs) provide a means to interrogate visual system functioning intraoperatively during tumor resection in which the optic pathway is at risk for injury. Due to technical limitations, fVEPs have remained underutilized in the armamentarium of intraoperative neurophysiological monitoring (IONM) techniques. Here we review the evolution of fVEPs as an IONM technique with emphasis on the enabling technological and intraoperative improvements. A combined approach with electroretinography (ERG) has enhanced feasibility of fVEP neuromonitoring as a practical application to increase safety and reduce error during tumor resection near the prechiasmal optic pathway. The major advance has been towards differentiating true cases of damage from false findings. We use two illustrative neurosurgical cases in which fVEPs were monitored with and without ERG to discuss limitations and demonstrate how ERG data can clarify false-positive findings in the operating room. Standardization measures have focused on uniformity of photostimulation parameters for fVEP recordings between neurosurgical groups.

Radiation-induced optic neuropathy (RION) is a rare disease caused by exposure of the optic nerves to radiation during radiotherapy procedures for head and neck tumours. The purpose of this study was to review and summarise the epidemiology, risk factors, clinical presentations, pathphysiology characteristics, diagnosis, and management of RION. Its occurrence is associated with cumulative doses of radiation above 50 Gy, presence of multi-morbidities and the presence of concomitant chemotherapy and radiotherapy. It manifests with acute, painless, and monocular loss of vision, and these symptoms appear late after the radiation exposure. The diagnosis of the disease occurs by exclusion and, mainly, by the clinical analysis of the case associated with the time of radiation exposure. Treatment does not seem promising and there is not an effective cure. In this review, we mainly focus on compiling existing information on the topic and providing knowledge for early diagnosis and more efficient treatment.

The visual pathways that bypass the primary visual cortex (V1) are often assumed to support visually guided behavior in humans in the absence of conscious vision. This conclusion is largely based on findings on patients: V1 lesions cause blindness but sometimes leave some visually guided behaviors intact-this is known as blindsight. With the aim of examining how well the findings on blindsight patients generalize to neurologically healthy individuals, we review studies which have tried to uncover transcranial magnetic stimulation (TMS) induced blindsight. In general, these studies have failed to demonstrate a completely unconscious blindsight-like capacity in neurologically healthy individuals. A possible exception to this is TMS-induced blindsight of stimulus presence or location. Because blindsight in patients is often associated with some form of introspective access to the visual stimulus, and blindsight may be associated with neural reorganization, we suggest that rather than revealing a dissociation between visually guided behavior and conscious seeing, blindsight may reflect preservation or partial recovery of conscious visual perception after the lesion.

Visual disabilities in central nervous system autoimmune diseases such as multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are important symptoms. Past studies have focused on neuro-inflammatory changes and demyelination in the white matter of the brain and spinal cord. In MS, neuro-inflammatory lesions have been diagnosed in the visual pathway; the lesions may perturb visual function. Similarly, neuropathological changes in the retina and optic nerves have been found in animals with chronic EAE. Although the retina and optic nerves are immunologically privileged sites via the blood-retina barrier and blood-brain barrier, respectively, inflammation can occur via other routes, such as the uvea (e.g., iris and choroid) and cerebrospinal fluid in the meninges. This review primarily addresses the direct involvement of the blood-retina barrier and the blood-brain barrier in the development of retinitis and optic neuritis in EAE models. Additional routes, including pro-inflammatory mediator-filled choroidal and subarachnoid spaces, are also discussed with respect to their roles in EAE-induced visual disability and as analogues of MS in humans.

The authors report intraoperative mapping with cortical visual evoked potentials during occipital tumor resection. This approach was valuable to reduce the risk of visual cortex and visual pathways damage and, accordingly, the likelihood of postoperative visual impairment. The peculiarity of this case is registration of clear cortical visual evoked potentials in various positions before and after tumor resection. Intraoperative monitoring was valuable to avoid damage to visual cortex and visual pathways during tumor resection. There was no postoperative visual deterioration. Moreover, we observed partial recovery of visual fields after resection of occipital malignant tumor.
В работе приводится клинический случай, показывающий возможность использования корковых зрительных вызванных потенциалов (ЗВП) при удалении опухоли затылочной доли для уменьшения риска повреждения зрительной коры и зрительных проводящих путей и, соответственно, для снижения вероятности ухудшения зрения после операции. Особенность клинического случая заключается в том, что нам удалось зарегистрировать четкие компоненты ЗВП в различных позициях до и после удаления опухоли. Благодаря проведенному мониторингу при удалении опухоли удалось обойти зрительную кору и проводящие зрительные пути. После нейрохирургического вмешательства с интраоперационной регистрацией корковых ЗВП нарастания зрительного дефицита не было, более того, отмечено частичное восстановление полей зрения после радикального удаления злокачественной опухоли затылочной доли.

Sarcoidosis is a multisystem granulomatous disorder of unknown nature. Patients often present with pulmonary, skin, eye, and orbital lesions. Involvement of the central nervous system (CNS) is accompanied by granulomatous leptomeningitis and damage to the basal brain structures with formation of granulomas near the cranial nerves, hypothalamus, pituitary gland, cavernous sinuses, optic chiasm, and intracranial optic nerves. The optic nerves can be affected independently of the other CNS regions, which may be the first manifestation of the disease. The article presents two clinical cases of sarcoidosis affecting the anterior visual pathway. Diagnosis of the disease was associated with certain difficulties. A biopsy revealed a sarcoidosis lesion.
Саркоидоз является мультисистемным гранулематозным заболеванием, природа которого неизвестна. Клинические проявления наблюдаются чаще со стороны легких, кожи, глаз и орбиты. При поражении центральной нервной системы (ЦНС) имеет место гранулематозный лептоменингит, а также поражение структур основания мозга с формированием гранулем около черепно-мозговых нервов, в области гипоталамуса, гипофиза, кавернозных синусов, хиазмы, интракраниальных отделов зрительных нервов. Зрительные нервы могут поражаться независимо от других отделов ЦНС, что может быть первым проявлением заболевания. В статье представлены два клинических наблюдения поражения структур переднего зрительного пути саркоидозом. Диагностика заболевания имела определенные трудности. Биопсия образования позволила уточнить саркоидозную природу поражения.

It is well-documented that patients with Huntington\'s disease (HD) exhibit specific deficits in visual cognition. A less well-documented literature also exists that suggests people with HD experience a number of disease-related changes to more rudimentary sensory visual processing. Here, we review evidence for the effects of HD on the integrity of the early visual pathways in humans along with changes to low-level visual sensitivity. We find evidence for reduced structural and functional integrity of the visual pathways, marked by retinal thinning, reduced VEP amplitude, and cell loss and thinning in visual cortex. We also find evidence of visual perceptual deficits, particularly for colour and motion. We suggest that future studies with well-defined HD and HD-related groups in appropriate numbers that systematically examine the relationship between structural changes to the visual system, basic visual perceptual deficits and disease stage/severity are therefore likely to yield promising results.

Bevacizumab (BVZ) is a vascular endothelial growth factor inhibitor that has been widely accepted since its introduction into the cancer pharmacopoeia. Anecdotal reports suggested improvements in vision in children with visual pathway glioma.
We report a boy with visual pathway glioma whose vision had deteriorated significantly on vincristine and carboplatin, to the point that he was registered blind. Following bevacizumab therapy, there was a dramatic improvement in vision with reduction in tumour volume. However, following 20 doses of BVZ given over 19 months, he developed a significant cerebrovascular stenosis.
The BVZ-induced cerebrovascular diseases in children are extremely rare but potentially serious. Importantly, stenosis has not been previously described in literature.