The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Uta Schick - One of the best experts on this subject based on the ideXlab platform.
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Prechiasmatic transection of the Optic Nerve in Optic Nerve glioma: technical description and surgical outcome.
Neurosurgical review, 2016Co-Authors: Hamid Borghei-razavi, Shunsuke Shibao, Uta SchickAbstract:Optic pathway glioma (OPG) encompasses a spectrum of findings ranging from lesions confined to the Optic Nerve only, lesions affecting the Optic chiasm and hypothalamus, and lesions with diffuse involvement of a large part of the Optic pathway and neighboring structures. The majority of pediatric low-grade astrocytomas in the Optic/chiasmatic region are typical pilocytic astrocytoma. The rest of them (10 %) may be other gliomas such as fibrillary pilomyxoid astrocytoma (grade 2 WHO). The postsurgical local recurrence rate of 55 to 76 % has been reported in some histological subtypes such as pilomyxoid astrocytoma (grade 2). Performing a prechiasmatic transection might offer a new surgical option to avoid further tumor growth toward the chiasm in the Optic Nerve glioma with predominantly orbital manifestations. In this retrospective study, four patients (three children, two without neurofibromatosis type 1 (NF1), and one with NF1 and one adult without NF1) with Optic Nerve glioma without involvement of the chiasm but blindness, disfiguring proptosis, and pain of the affected eye were included. The surgical approach was performed as a combined approach from pterional extradural and intradural. Without any exceptions, vision of the contralateral eye could be preserved and did not show any deterioration after surgery or during the follow-up time between 17 and 106 months. Furthermore, in all patients, gross total tumor resection could be achieved. During follow-up observation in all patients, no further tumor progress or recurrences could be observed. None of the patients were treated postoperatively by radiotherapy or chemotherapy. Prechiasmatic transection of the Optic Nerve in Optic Nerve glioma without affecting the chiasm might offer a surgical treatment option to control tumor growth and to preserve vision of the contralateral eye.
Michael J. Wilkinson - One of the best experts on this subject based on the ideXlab platform.
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Treatment of pseudotumor cerebri by primary and secondary Optic Nerve sheath decompression.
American journal of ophthalmology, 1991Co-Authors: Thomas C. Spoor, John M. Ramocki, Matthew P. Madion, Michael J. WilkinsonAbstract:We performed Optic Nerve sheath decompression in 53 patients (101 eyes) with pseudotumor cerebri and visual loss. Sixty-nine eyes (85 patients) with acute papilledema uniformly had improved visual function after Optic Nerve sheath decompression. Of 32 eyes with chronic papilledema (18 patients), only ten had improved visual function after Optic Nerve sheath decompression. This difference was significant (P = .0001). Thirteen eyes required secondary or tertiary Optic Nerve sheath decompression after an initial successful result. Eleven of 13 eyes had improved visual function after repeat Optic Nerve sheath decompression. We believe that patients with acute papilledema and visual loss should be offered Optic Nerve sheath decompression, and if symptoms recur, repeat Optic Nerve sheath decompression is a safe and effective treatment option.
Sohan Singh Hayreh - One of the best experts on this subject based on the ideXlab platform.
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laser doppler flowmetry and Optic Nerve head blood flow
American Journal of Ophthalmology, 1999Co-Authors: Benno L Petrig, Charles E Riva, Sohan Singh HayrehAbstract:Abstract Purpose: Ischemic disorders of the Optic Nerve head constitute an important cause of visual loss. The Optic Nerve head is supplied by two main sources of blood flow: the superficial layers by the central retinal artery and the deeper layers by the posterior ciliary arteries. This study was conducted in rhesus monkey eyes to obtain a better understanding of which part of the Optic Nerve head circulation is measured by laser Doppler flowmetry. Methods: By means of a fundus camera–based laser Doppler flowmetry technique to measure blood flow in the Optic Nerve head tissue, laser Doppler flowmetry measurements were taken at baseline and then after experimental occlusion of central retinal artery (12 eyes), posterior ciliary arteries (nine eyes), and combined occlusion of central retinal artery and posterior ciliary arteries (nine eyes). Optic Nerve head, choroidal, and retinal circulations were investigated by fluorescein fundus angiography after the various arterial occlusions. Reseults: Average laser Doppler flowmetry flow during central retinal artery occlusion alone was significantly decreased ( P P P > .20). After posterior ciliary artery occlusion alone, however, measurements showed a nonsignificant increase in laser Doppler flowmetry flow of 17% ± 37%. Conclusions: The findings of this study suggest that the standard laser Doppler flowmetry technique is predominantly sensitive to blood flow changes in the superficial layers of the Optic Nerve head and less sensitive to those in the prelaminar and deeper regions, and their relative proportions are not known. In this laser Doppler flowmetry technique, the weaker Doppler signal from the deep layers cannot be separated from the dominant signal from the superficial layers to exclusively study the circulation in the deep layers; the latter circulation is of interest in Optic Nerve head ischemic disorders, including glaucoma. Emerging new Optical modalities of the laser Doppler flowmetry technique may help in selectively measuring blood flow in the deeper layers.
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the 1994 von sallman lecture the Optic Nerve head circulation in health and disease
Experimental Eye Research, 1995Co-Authors: Sohan Singh HayrehAbstract:This is a brief overview of multifaceted anatomical, experimental and clinical studies conducted by the author since 1955 on the Optic Nerve head circulation in health and disease. Conclusions, based on the accumulated information provided by these studies, are summarized. The studies on the pattern of blood supply of the Optic Nerve head have shown that: (a) its main source of blood supply is the posterior ciliary artery circulation, with retinal circulation supplying only the surface Nerve fiber layer, (b) there is marked interindividual variation in the blood supply pattern, and (c) the blood supply in the Optic Nerve head has a sectoral distribution. The various factors which produce interindividual variation in the blood supply of the Optic Nerve head are discussed, particularly those in the posterior ciliary artery circulation; this is because all available evidence indicates that it is derangement in the posterior ciliary circulation in the Optic Nerve head that is primarily responsible for the common ischemic disorders of the Optic Nerve head, e.g. anterior ischemic Optic neuropathy and glaucomatous Optic neuropathy. Factors that may derange the blood flow in the Optic Nerve head include defective autoregulation of blood flow in it, vascular changes in its feeding arteries, hematologic abnormalities, systemic arterial hypertension and hypotension, and intraocular pressure; their roles are discussed. For better understanding and management of Optic Nerve head ischemic disorders, there is an urgent need for an accurate clinical method of assessment of blood flow in the posterior ciliary circulation in Optic Nerve head, since no satisfactory method is currently available. Redness or pallor of the Optic disk on ophthalmoscopy is not a true guide to the Optic Nerve head vascularity as it gives no information about the state of the posterior ciliary circulation. Fluorescein fundus angiography, though far superior to the Optic disk color for evaluation of Optic Nerve head vascularity, has a number of limitations. All these topics and various controversies about them are discussed briefly.
Bradley K. Farris - One of the best experts on this subject based on the ideXlab platform.
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pseudotumor cerebri and Optic Nerve sheath decompression
Ophthalmology, 2000Co-Authors: James T Banta, Bradley K. FarrisAbstract:Abstract Objective To determine the efficacy and safety of Optic Nerve sheath decompression in a large population of patients with pseudotumor cerebri with visual loss despite medical treatment and to suggest a treatment algorithm on the basis of these data. Design Retrospective, noncomparative, interventional case series. Participants One hundred fifty-eight eyes in 86 patients with pseudotumor cerebri. Intervention Optic Nerve sheath decompression. Main outcome measures Visual acuity, visual fields, and surgical complications. Results After Optic Nerve sheath decompression for pseudotumor cerebri, visual acuity stabilized or improved in 148 of 158 (94%) eyes, and visual fields stabilized or improved in 71 of 81 (88%) eyes. Surgical complications, most of which were transient and benign, were seen in 39 of 86 patients. Only one eye in one patient had permanent severe visual loss secondary to an operative complication. Conclusions In patients with pseudotumor cerebri with progressive visual loss despite maximum medical therapy, Optic Nerve sheath decompression is a safe and effective means of stabilizing visual acuity and the visual fields of those tested.
Michael Blumenthal - One of the best experts on this subject based on the ideXlab platform.
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Optic Nerve compression by carotid arteries in low tension glaucoma
Graefes Archive for Clinical and Experimental Ophthalmology, 1993Co-Authors: Isaac Gutman, Isaac Ashkenazi, Shlomo Melamed, Michael BlumenthalAbstract:Low-tension glaucoma (LTG) is manifested by glaucomatous Optic Nerve damage and visual field loss despite normal intraocular pressure (IOP). We describe 62 patients with classical signs of LTG. Computed tomography (CT) was performed in all patients. In 56 of the patients (90.3%), pathology of the intracavernous carotid arteries adjacent to the intracranial opening of the Optic canal could be demonstrated. In 28 patients (45.2%) a clear asymmetry of the Optic Nerve cupping was found and could be correlated with the severity of the carotid artery pathology. A control group of 24 age-matched patients included five (20.8%) with intracavernous carotid artery calcification and only one (4.2%) with intracavernous ectasia. We suggest that calcification, dilatation and ectasia of the carotid artery into the Optic canal may play an important role in the pathogenesis of many cases of LTG. The close proximity of the carotid artery to the Optic Nerve at this location may result in compressive neuropathy with subsequent glaucomatous damage of the Optic Nerve head.
