Neuro-ophthalmology publications

Bauer CM, Cattaneo Z, Merabet LB. Early Blindness is Associated with Increased Volume of the Uncinate Fasciculus. Eur J Neurosci 2018;Abstract
Growing evidence demonstrates dramatic structural and functional neuroplastic changes in individuals born with early onset blindness. For example, crossmodal sensory processing at the level of the occipital cortex appears to be associated with adaptive behaviors in the blind. However, detailed studies examining the structural properties of key white matter pathways in other regions of the brain remain limited. Given that blind individuals rely heavily on their sense of hearing, we examined the structural properties of two important pathways involved with auditory processing namely, the uncinate and arcuate fasciculi. High angular resolution diffusion imaging (HARDI) tractography was used to examine structural parameters (i.e. tract volume and quantitative anisotropy, or QA) of these two fasciculi in a sample of 13 early blind individuals and 14 normally sighted controls. Compared to controls, early blind individuals showed a significant increase in the volume of the left uncinate fasciculus. A small area of increased QA was also observed half way along the right arcuate fasciculus in the blind group. These findings contribute to our knowledge regarding the broad neuroplastic changes associated with profound early blindness. This article is protected by copyright. All rights reserved.
M Mallery R, Poolman P, J Thurtell M, Full JM, Ledolter J, Kimbrough D, Frohman EM, Frohman TC, Kardon RH. Visual Fixation Instability in Multiple Sclerosis Measured Using SLO-OCT. Invest Ophthalmol Vis Sci 2018;59(1):196-201.Abstract
Purpose: Precise measurements of visual fixation and its instability were recorded during optical coherence tomography (OCT) as a marker of neural network dysfunction in multiple sclerosis (MS), which could be used to monitor disease progression or response to treatment. Methods: A total of 16 MS patients and 26 normal subjects underwent 30 seconds of scanning laser ophthalmoscope (SLO)-based eye tracking during OCT scanning of retinal layer thickness. Study groups consisted of normal eyes, MS eyes without prior optic neuritis (MS wo ON), and MS eyes with prior optic neuritis (MS + ON). Kernel density estimation quantified fixation instability from the distribution of fixation points on the retina. In MS wo ON eyes, fixation instability was compared to other measures of visual and neurologic function. Results: Fixation instability was increased in MS wo ON eyes (0.062 deg2) compared to normal eyes (0.030 deg2, P = 0.015). A further increase was seen for MS + ON eyes (0.11 deg2) compared to MS wo ON (P = 0.04) and normal (P = 0.006) eyes. Fixation instability correlated weakly with ganglion cell layer (GCL) volume and showed no correlation with low-contrast letter acuity, EDSS score, or SDMT score. Conclusions: Fixation instability reflects the integrity of a widespread neural network germane to visual processing and ocular motor control, and is disturbed in MS. Further study of visual fixation, including the contribution of microsaccades to fixation instability, may provide insight into the localization of fixation abnormalities in MS and introduce innovative and easily measured outcomes for monitoring progression and treatment response.
Gaier ED, Gilbert AL, Cestari DM, Miller JB. Optical coherence tomographic angiography identifies peripapillary microvascular dilation and focal non-perfusion in giant cell arteritis. Br J Ophthalmol 2017;Abstract
AIMS: We set out to determine the optical coherence tomographic angiography (OCT-A) characteristics of arteritic anterior ischaemic optic neuropathy (AAION) in the context of giant cell arteritis (GCA). METHODS: This is an observational case series of four patients with AAION secondary to GCA, three with unilateral AAION and one with bilateral AAION. We reviewed the charts, fundus photography, visual fields, fluorescein angiography (FA) and OCT-A images for all patients to identify a unifying theme in a range of AAION clinical severity. Imaging of two healthy control eyes from two patients of similar age to the patients in our series were used for comparison. RESULTS: Superficial peripapillary capillary dilation was seen in eyes with acute AAION. It was also noted in the fellow eyes of two patients. Retinal capillary perfusion defects corresponded to visual field loss. Dense optic disc oedema and cotton-wool spots imparted blockage effects. OCT-A laminar analysis did not highlight the choroidal/choriocapillaris perfusion defects seen on FA in two patients. Follow-up OCT-A was obtained in two patients and revealed progression to superficial peripapillary capillary attenuation that corresponded with visual field loss. CONCLUSIONS: There are acute and chronic vascular changes in AAION that are detectable by OCT-A that correspond with visual function. Though the microvascular changes seen in GCA and AAION are not specific, the nearly ubiquitous findings among preclinical and clinically affected eyes in this series of patients with GCA support OCT-A as a potentially useful adjunctive diagnostic test in the work-up of ambiguous cases of suspected ischaemic optic neuropathy.
Chwalisz BK, Bouffard MA, Prasad S, Cestari DM. Neuroimaging diagnostic and monitoring approaches in ophthalmology. Curr Opin Neurol 2017;Abstract
PURPOSE OF REVIEW: We review new applications of optical coherence tomography (OCT) technology in neuro-ophthalmology. We also describe new technologies for visualizing the extracranial vessels in the diagnosis of giant cell arteritis (GCA). RECENT FINDINGS: Newer OCT modalities are expanding the evaluation of the optic disc, and are being applied to a number of neurologic conditions such as demyelinating and neurodegenerative disease. Swept-source OCT and enhanced-depth imaging OCT are refining the fine-grained analysis of the optic nerve head in the diagnosis of papilledema and optic nerve drusen. OCT-angiography is opening up new avenues to the study of the vasculature of the optic nerve head and its disorders, including ischemic optic neuropathy. Newer technologies in the diagnosis of GCA include vascular ultrasound, magnetic resonance imaging (MRI) of the extracranial vasculature and PET imaging of the large vessels. SUMMARY: OCT and several of its derivations are advancing diagnosis, and in some cases prognostication, in a variety of inflammatory, ischemic and compressive optic neuropathies. These technologies hold potential in the laboratory as well, yielding insights into the mechanisms of a variety of neurological conditions. In addition, further developments in MRI and ultrasonography techniques are shaping the approach to the diagnosis of GCA.
Zhang M, Gilbert A, Hunter D. Superior oblique myokymia. Surv Ophthalmol 2017;Abstract
Superior oblique myokymia (SOM) is a rare condition of unclear etiology. We discuss the history, etiology, clinical features, differential diagnoses, management and prognosis of SOM. We conducted a meta-analysis of all 116 cases published since SOM was first described in 1906. The age at examination was 17-72 years (mean 42 years.) There was a right-sided preponderance in 61% of cases (P < 0.02) that was statistically significant in females (63%, P < 0.04) but not in males (59%, P = 0.18). The pathophysiology of SOM may be neurovascular compression and/or ephaptic transmission. Although various pharmacological and surgical approaches to SOM treatment have been proposed, the rarity of the condition has made it impossible to conduct clinical trials evaluating the safety and efficacy of these approaches. Recently, topical beta-blockers have managed SOM symptoms in a number of cases, including the first case treated with levobunolol. Systemic medications, strabismus surgery, and neurosurgery have been used to control symptoms, with strabismus surgery carrying a moderate risk of post-operative diplopia in down-gaze. While there is no established treatment for SOM, we encourage clinicians to attempt topical levobunolol therapy before considering systemic therapy or surgery.
Heidary G. Neuro-Ophthalmic Manifestations of Pediatric Neurodegenerative Disease. J Neuroophthalmol 2017;37 Suppl 1:S4-S13.Abstract
The topic of pediatric neurodegenerative disease is broad and ever expanding. Children who suffer from neurodegenerative disease often have concomitant visual dysfunction. Neuro-ophthalmologists may become involved in clinical care to identify corroborating eye findings when a specific condition is suspected, to monitor for disease progression, and in some cases, to assess treatment efficacy. Ophthalmic findings also may be the harbinger of a neurodegenerative process so a keen awareness of the possible manifestations of these conditions is important. The purpose of this review is to highlight common examples of the neuro-ophthalmic manifestations of pediatric neurodegenerative disease using a case-based approach in an effort to provide a framework for approaching these complex patients.
Jeng-Miller KW, Cestari DM, Gaier ED. Congenital anomalies of the optic disc: insights from optical coherence tomography imaging. Curr Opin Ophthalmol 2017;28(6):579-586.Abstract
PURPOSE OF REVIEW: Congenital anomalies of the optic nerve are rare but significant causes of visual dysfunction in children and adults. Accurate diagnosis is dependent on a thorough funduscopic examination, but can be enhanced by imaging information garnered from optical coherence tomography (OCT). We review common congenital optic nerve anomalies, including optic disc pit, optic nerve coloboma, morning glory disc anomaly, and hypoplasia of the optic nerve, review their systemic associations, and discuss insights from OCT imaging. RECENT FINDINGS: Optic disc pits are a result of a defect in the lamina cribrosa and abnormal vitreomacular adhesions have been shown to cause maculopathy. In patients with optic nerve colobomas, OCT can be instrumental in diagnosing choroidal neovascularization, a rare but visually devastating complication. The pathogenesis of morning glory disc anomaly has been more clearly elucidated by OCT as occurring from a secondary postnatal mesenchymal abnormality rather than only the initial neuroectodermal dysgenesis of the terminal optic stalk in isolation. OCT studies of optic nerve hypoplasia have demonstrated significant thinning of the inner and outer retinal layers of the perifoveal region and thicker layers in the fovea itself, resulting in a foveal hypoplasia-like pathology, that is, significantly correlated to poorer visual outcomes. SUMMARY: OCT provides detailed in-vivo analysis of these anatomic anomalies and their resulting pathologies, shedding new insights on the pathogenesis, diagnosis, and potential visual outcomes of these conditions in children. Further study employing OCT to elucidate structure-function relationships of congenital optic nerve anomalies will help expand the role of OCT in clinical practice related to diagnosis, prognosis, and management of these entities.
Chun BY, Cestari DM. Advances in experimental optic nerve regeneration. Curr Opin Ophthalmol 2017;28(6):558-563.Abstract
PURPOSE OF REVIEW: Recent advances in experimental studies of optic nerve regeneration to better understand the pathophysiology of axon regrowth and provide insights into the future treatment of numerous optic neuropathies. RECENT FINDINGS: The optic nerve is part of the central nervous system and cannot regenerate if injured. There are several steps that regenerating axons of retinal ganglion cells (RGCs) must take following optic nerve injury that include: maximizing the intrinsic growth capacity of RGCs, overcoming the extrinsic growth-inhibitory environment of the optic nerve, and optimizing the reinnervation of regenerated axons to their targets in the brain. Recently, some degree of experimental optic nerve regeneration has been achieved by factors associated with inducing intraocular inflammation, providing exogenous neurotrophic factors, reactivating intrinsic growth capacity of mature RGCs, or by modifying the extrinsic growth-inhibitory environment of the optic nerve. In some experiments, regenerating axons have been shown to reinnervate their central targets in the brain. SUMMARY: Further approaches to the combination of aforementioned treatments will be necessary to develop future therapeutic strategy to promote ultimate regeneration of the optic nerve and functional vision recovery after optic nerve injury.
Gamond L, Vecchi T, Ferrari C, Merabet LB, Cattaneo Z. Emotion processing in early blind and sighted individuals. Neuropsychology 2017;31(5):516-524.Abstract
OBJECTIVE: Emotion processing is known to be mediated by a complex network of cortical and subcortical regions with evidence of specialized hemispheric lateralization within the brain. In light of prior evidence indicating that lateralization of cognitive functions (such as language) may depend on normal visual development, we investigated whether the lack of prior visual experience would have an impact on the development of specialized hemispheric lateralization in emotional processing. METHOD: We addressed this issue by comparing performance in early blind and sighted controls on a dichotic listening task requiring the detection of specific emotional vocalizations (i.e., suggestive of happiness or sadness) presented independently to either ear. RESULTS: Consistent with previous studies, we found that sighted individuals showed enhanced detection of positive vocalizations when presented in the right ear (i.e., processed within the left hemisphere) and negative vocalizations when presented in the left ear (i.e., right hemisphere). It is interesting to note that although blind individuals were as accurate as sighted controls in detecting the valance of the vocalization, performance was not consistent with any pattern of specialized hemispheric lateralization. CONCLUSIONS: Overall, these results suggest that although the lack of prior visual experience may not lead to impaired emotion processing performance, the underlying neurophysiological substrate (i.e., degree of special hemispheric lateralization) may depend on normal visual development. (PsycINFO Database Record