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Sohan Singh Hayreh - One of the best experts on this subject based on the ideXlab platform.
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pathogenesis of Optic Disc edema in raised intracranial pressure
Progress in Retinal and Eye Research, 2016Co-Authors: Sohan Singh HayrehAbstract:Abstract Optic Disc edema in raised intracranial pressure was first described in 1853. Ever since, there has been a plethora of controversial hypotheses to explain its pathogenesis. I have explored the subject comprehensively by doing basic, experimental and clinical studies. My objective was to investigate the fundamentals of the subject, to test the validity of the previous theories, and finally, based on all these studies, to find a logical explanation for the pathogenesis. My studies included the following issues pertinent to the pathogenesis of Optic Disc edema in raised intracranial pressure: the anatomy and blood supply of the Optic nerve, the roles of the sheath of the Optic nerve, of the centripetal flow of fluids along the Optic nerve, of compression of the central retinal vein, and of acute intracranial hypertension and its associated effects. I found that, contrary to some previous claims, an acute rise of intracranial pressure was not quickly followed by production of Optic Disc edema. Then, in rhesus monkeys, I produced experimentally chronic intracranial hypertension by slowly increasing in size space-occupying lesions, in different parts of the brain. Those produced raised cerebrospinal fluid pressure (CSFP) and Optic Disc edema, identical to those seen in patients with elevated CSFP. Having achieved that, I investigated various aspects of Optic Disc edema by ophthalmoscopy, stereoscopic color fundus photography and fluorescein fundus angiography, and light microscopic, electron microscopic, horseradish peroxidase and axoplasmic transport studies, and evaluated the effect of opening the sheath of the Optic nerve on the Optic Disc edema. This latter study showed that opening the sheath resulted in resolution of Optic Disc edema on the side of the sheath fenestration, in spite of high intracranial CSFP, proving that a rise of CSFP in the sheath was the essential pre-requisite for the development of Optic Disc edema. I also investigated Optic Disc edema with raised CSFP in patients, by evaluating Optic Disc and fundus changes by stereoscopic fundus photography and fluorescein fundus angiography. Based on the combined information from all the studies Discussed above, it is clear that the pathogenesis of Optic Disc edema in raised intracranial pressure is a mechanical phenomenon. It is primarily due to a rise of CSFP in the Optic nerve sheath, which produces axoplasmic flow stasis in the Optic nerve fibers in the surface nerve fiber layer and prelaminar region of the Optic nerve head. Axoplasmic flow stasis then results in swelling of the nerve fibers, and consequently of the Optic Disc. Swelling of the nerve fibers and of the Optic Disc secondarily compresses the fine, low-pressure venules in that region, resulting in venous stasis and fluid leakage; that leads to the accumulation of extracellular fluid. Contrary to the previous theories, the various vascular changes seen in Optic Disc edema are secondary and not primary. Thus, Optic Disc edema in raised CSFP is due to a combination of swollen nerve fibers and the accumulation of extracellular fluid. My studies also provided information about the pathogeneses of visual disturbances in raised intracranial pressure.
Patrick A Sibony - One of the best experts on this subject based on the ideXlab platform.
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the Optic Disc drusen studies consortium recommendations for diagnosis of Optic Disc drusen using Optical coherence tomography
Journal of Neuro-ophthalmology, 2017Co-Authors: Lasse Malmqvist, Lulu L C D Bursztyn, Fiona Costello, Kathleen B Digre, Alexander J Fraser, Clare L Fraser, Bradley J Katz, Mitchell Lawlor, Axel Petzold, Patrick A SibonyAbstract:Background:Making an accurate diagnosis of Optic Disc drusen (ODD) is important as part of the work-up for possible life-threatening Optic Disc edema. It also is important to follow the slowly progressive visual field defects many patients with ODD experience. The introduction of enhanced depth imag
Petros Petrou - One of the best experts on this subject based on the ideXlab platform.
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Optic Disc pit: a review
Graefe's Archive for Clinical and Experimental Ophthalmology, 2011Co-Authors: Ilias Georgalas, Ioannis Ladas, Gerasimos Georgopoulos, Petros PetrouAbstract:Background Since Wiethe first described the clinical presentation of two Optic Disc depressions in a 62-year-old woman in 1882, there have been many studies addressing what later become known as the “Optic Disc pit.” The main complication of this condition, termed Optic Disc pit maculopathy, is associated with visual deterioration. Treatment of Optic Disc pit maculopathy remains challenging. Methods Here we review the body of literature that documents the clinical findings, pathophysiology, histology, main complications, treatment options, special features and presentations, and differential diagnosis of Optic Disc pit. Results The source of the intraretinal fluid in Optic Disc pit maculopathy remains controversial. Four possible sources of this fluid have been proposed: fluid from the vitreous cavity; cerebrospinal fluid originating from the subarachnoid space; fluid from leaky blood vessels at the base of the pit; and fluid from the orbital space surrounding the dura. Conclusions Optic Disc pits are a very rare clinical entity, affecting approximately one in 11,000 people. Patients with congenital Optic Disc pit sometimes remain asymptomatic, but 25% to 75% present with visual deterioration in their 30s or 40s after developing macular schisis and detachment. The most widely accepted treatment for such patients is a surgical approach involving pars plana vitrectomy with or without internal limiting membrane peeling, with or without endolaser photocoagulation and C3F8 endotamponade.
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Optic Disc pit a review
Graefes Archive for Clinical and Experimental Ophthalmology, 2011Co-Authors: Ilias Georgalas, Ioannis Ladas, Gerasimos Georgopoulos, Petros PetrouAbstract:Background Since Wiethe first described the clinical presentation of two Optic Disc depressions in a 62-year-old woman in 1882, there have been many studies addressing what later become known as the “Optic Disc pit.” The main complication of this condition, termed Optic Disc pit maculopathy, is associated with visual deterioration. Treatment of Optic Disc pit maculopathy remains challenging.
Richard F Spaide - One of the best experts on this subject based on the ideXlab platform.
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multimodal imaging of Optic Disc drusen
American Journal of Ophthalmology, 2013Co-Authors: Taku Sato, Sarah Mrejen, Richard F SpaideAbstract:Purpose To evaluate Optic Disc drusen, extracellular protein deposits known to contain numerous aggregates of mitochondria, using multimodal modalities featuring Optical coherence tomography (OCT) and autofluorescence imaging. Design Retrospective observational case series. Methods Eyes with Optic nerve drusen were examined with enhanced depth imaging (EDI)-OCT, swept source OCT, and fundus autofluorescence using a fundus camera. Results Twenty-six eyes of 15 patients with Optic Disc drusen were evaluated. EDI-OCT and swept source OCT showed multiple Optic Disc drusen at different levels; most were located immediately anterior to the lamina cribrosa. The drusen were ovoid regions of lower reflectivity that were bordered by hyperreflective material, and in 12 eyes (46.2%) there were internal hyperreflective foci. The mean diameter of the Optic Disc drusen as measured in OCT images was 686.8 (standard deviation ± 395.2) μm. There was a significant negative correlation between the diameter of the Optic Disc drusen and the global retinal nerve fiber layer thickness (r = −0.61, P = .001). There was a significant negative correlation between proportion of the Optic Disc drusen area occupied by Optic nerve drusen as detected by autofluorescence imaging and the global retinal nerve fiber layer thickness (r = −0.63, P = .001). Conclusions Deeper-penetration OCT imaging demonstrated the internal characteristics of Optic Disc drusen and their relationship with the lamina cribrosa in vivo. This study also showed that both the larger the drusen and the more area of the Optic canal occupied by drusen, the greater the associated retinal nerve fiber layer abnormalities.
S W Park - One of the best experts on this subject based on the ideXlab platform.
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RetCam image analysis of the Optic Disc in premature infants
Eye, 2013Co-Authors: J W Park, S W ParkAbstract:Purpose To evaluate the correlation between Optic Disc parameters and birth weight or gestational age in premature infants. Methods RetCam fundal images were taken of 97 premature infants who needed screening for retinopathy of prematurity and who had no ischemic brain injury. The images were taken at a postmenstrual age of 36 weeks and analyzed. The Optic Disc cup to Disc ratio, Optic Disc area, rim area, and cup to Disc area ratio were calculated using image analysis. We evaluated the relationship between these Optic Disc parameters and gestational age or birth weight. Results The Optic cup to Disc ratio was less than 0.15 in 139 eyes (71.6%) and 0.5 or more in six eyes (3.1%). The Optic cup Disc area ratio was less than 0.05 in 146 eyes (75.3%) and 0.3 or more in four eyes (2.1%). On evaluating the association between Optic Disc parameters and gestational age or birth weight, Optic Disc cup to Disc ratio, Optic Disc area, rim area, and cup to Disc area ratio did not show significant relationships. Conclusion The Optic Disc parameters of premature infants had no correlation with birth weight and gestational age.