Retrobulbar diameter of optic nerve in glaucoma

Introduction. The ultrasound diagnostics of the optic nerve includes the analysis of the optic nerve disc (PNO) and measuring of its retrobulbar diameter. With B-scan, by Schraeder's method, it is possible to measure very precisely the optic nerve, the pial diameter, the normal values for the pial diameter being 2.8-4.1 mm. In glaucoma, the disease that is most frequently associated with higher intraocular pressure, there comes the destruction of nerve fibres, which can be visualized as the excavation of the optic nerve disc. Objective. In this paper, we were interested in finding whether in glaucoma, and in what phase of the disease, the optic nerve starts growing thinner. Aware of many forms of this very complex disease, we were interested in knowing if the visualization of excavation on the optic nerve disc is related to diminishing of the pial diameter of the retrobulbar nerve part. Methods. There were treated the patients who had already had the diagnosis of glaucoma and the visualized excavation of the optic disc of various dimensions. Echographically, there was measured the thickness of the retrobulbar part of the optic nerve and the finding compared in relation to the excavation of the optic disc. Results. In all eyes with glaucoma, a normal size of the retrobulbar part of the optic nerve was measured, ranging from 3.01 to 3.91 mm with the median of 3.36 mm. Also, by testing the correlation between the thickness of the optic nerve and the excavation of the PNO, by Pearson test, we found that there was no correlation between these two parameters (r=0.109; p>0.05). Conclusion. In the patients with glaucoma, the retrobulbar part of the optic nerve is not thinner (it has normal values), even not in the cases with a totally excavated optic disc. There is no connection between the size of the PNO excavation and the thickness of the retrobulbar part of the optic nerve.

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Different IOP, different diseases?

Modeling and Artificial Intelligence in Ophthalmology ◽

10.35119/maio.v1i2.25 ◽

2016 ◽

Vol 1 (2) ◽

pp. 97-102

Author(s):

Michele Iester ◽

Elisa D’Alessandro

Keyword(s):

Intraocular Pressure ◽

Optic Nerve ◽

Visual Field ◽

Optic Disc ◽

Progressive Disease ◽

Clinical Findings ◽

Nerve Fibers ◽

Visual Field Defects ◽

Chronic Progressive Disease ◽

Field Defects

Glaucoma is a chronic, progressive disease characterized by typical optic nerve head changes and visual field defects. These alterations are caused by an intraocular pressure (IOP) being too high for the wellbeing of the specific optic disc. Typical clinical findings in glaucoma patients include thinning of the optic disc rim (Fig. 1), loss of retinal nerve fibers in the inferior sector with subsequent visual field defects in the superior sector.

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The relation between the thickness of retrobulbar part of the optic nerve, measured by ultrasound, and the degree of prominence of the optic disc in stasis of the optic nerve

Srpski arhiv za celokupno lekarstvo ◽

10.2298/sarh0612479s ◽

2006 ◽

Vol 134 (11-12) ◽

pp. 479-481 ◽

Cited By ~ 1

Author(s):

Ivan Stefanovic ◽

Anka Stanojevic-Paovic ◽

Vaso Antunovic

Keyword(s):

Optic Nerve ◽

Intracranial Pressure ◽

Optic Disc ◽

Increased Intracranial Pressure ◽

Clinical Center ◽

Two Parameters

Introduction: The etiology of the noninflamed edema of the optic disc, or the stasis of the same, is related to a large number of various illnesses which result in the increased intracranial pressure. When examining fundus, an edema of the optic disc is found which can be quantitatively expressed in diopters, while retrobulbar part of the optic nerve can be measured by ultrasonography. Objective: The Objective of our investigation is to explore the relation of the optic disc prominence and the degree of thickness of retrobulbar part of the optic nerve. Method: Study included 21 patients with the increased intracranial pressure, treated at the Institute of Neurosurgery, Clinical Center of Serbia, that is, 41 eyes that manifested stasis of the optic nerve. Echographically, by means of Schraeder?s Method, the thickness of retrobulbar part of the optic nerve was measured and the degree of the optic disc prominence was clinically determined in diopters. Results: The thickened optic nerve was confirmed in all patients. Using Pearson?s correlation, the relation between the degree of the optic nerve thickness and the prominence of the same was analyzed, and it was found that there was no significant correlation between these two parameters. Conclusion: Instead of Conclusion, we shall ask a question: How relevant is dogma that the prominence of the optic disc more than 3D should be considered the optic disc stasis? The authors think that rating of the optic disc prominence in diopters is not justified.

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Two-Stage Mask-RCNN Approach for Detecting and Segmenting the Optic Nerve Head, Optic Disc, and Optic Cup in Fundus Images

Applied Sciences ◽

10.3390/app10113833 ◽

2020 ◽

Vol 10 (11) ◽

pp. 3833 ◽

Cited By ~ 3

Author(s):

Haidar Almubarak ◽

Yakoub Bazi ◽

Naif Alajlan

Keyword(s):

Optic Nerve ◽

Optic Disc ◽

Optic Nerve Head ◽

Fine Tuning ◽

Fundus Images ◽

Two Stage ◽

Second Stage ◽

Retinal Fundus Images ◽

Tuning Strategy ◽

Retinal Fundus

In this paper, we propose a method for localizing the optic nerve head and segmenting the optic disc/cup in retinal fundus images. The approach is based on a simple two-stage Mask-RCNN compared to sophisticated methods that represent the state-of-the-art in the literature. In the first stage, we detect and crop around the optic nerve head then feed the cropped image as input for the second stage. The second stage network is trained using a weighted loss to produce the final segmentation. To further improve the detection in the first stage, we propose a new fine-tuning strategy by combining the cropping output of the first stage with the original training image to train a new detection network using different scales for the region proposal network anchors. We evaluate the method on Retinal Fundus Images for Glaucoma Analysis (REFUGE), Magrabi, and MESSIDOR datasets. We used the REFUGE training subset to train the models in the proposed method. Our method achieved 0.0430 mean absolute error in the vertical cup-to-disc ratio (MAE vCDR) on the REFUGE test set compared to 0.0414 obtained using complex and multiple ensemble networks methods. The models trained with the proposed method transfer well to datasets outside REFUGE, achieving a MAE vCDR of 0.0785 and 0.077 on MESSIDOR and Magrabi datasets, respectively, without being retrained. In terms of detection accuracy, the proposed new fine-tuning strategy improved the detection rate from 96.7% to 98.04% on MESSIDOR and from 93.6% to 100% on Magrabi datasets compared to the reported detection rates in the literature.

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Optic disc coloboma (the morning glory syndrome) and optic nerve coloboma associated with transsphenoidal meningoencephalocele

European Journal of Radiology Extra ◽

10.1016/s1571-4675(03)00008-7 ◽

2003 ◽

Vol 45 (2) ◽

pp. 71-76 ◽

Cited By ~ 2

Author(s):

Mutlu Sağlam ◽

Üzeyir Erdem ◽

Murat Kocaoğlu ◽

Cem Tayfun ◽

Taner Üçöz ◽

...

Keyword(s):

Optic Nerve ◽

Optic Disc ◽

Morning Glory ◽

Morning Glory Syndrome ◽

Optic Disc Coloboma ◽

Optic Nerve Coloboma

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The Impact of Intraocular Pressure Elevation on Optic Nerve Head and Choroidal Blood Flow

Investigative Opthalmology & Visual Science ◽

10.1167/iovs.18-23872 ◽

2018 ◽

Vol 59 (8) ◽

pp. 3488 ◽

Cited By ~ 8

Author(s):

Naoki Kiyota ◽

Yukihiro Shiga ◽

Kohei Ichinohasama ◽

Masayuki Yasuda ◽

Naoko Aizawa ◽

...

Keyword(s):

Blood Flow ◽

Intraocular Pressure ◽

Optic Nerve ◽

Optic Nerve Head ◽

Choroidal Blood Flow ◽

Pressure Elevation ◽

Intraocular Pressure Elevation ◽

The Impact

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The synaptic organization of optic afferents in the amphibian tectum

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1974.0086 ◽

1974 ◽

Vol 187 (1089) ◽

pp. 421-447 ◽

Cited By ~ 39

Keyword(s):

Optic Nerve ◽

Cell Layer ◽

Maximum Amplitude ◽

Synaptic Organization ◽

Nerve Fibres ◽

Synaptic Potentials ◽

Postsynaptic Cell ◽

Optic Fibre ◽

Stimulation Of

Potentials in the amphibian tectum, evoked by stimulation of the optic nerve, were recorded extracellularly. Four discrete potentials, referred to as the m 1 , m 2 , u 1 and u 2 waves, occur at different latencies after stimulation. We have shown that these waves represent summed post-synaptic potentials generated by synchronous activation of four different groups of optic nerve fibres. The m 1 and m 2 waves are generated by two classes of myelinated optic nerve fibres, previously characterized as ‘dimming’ and ‘event’ fibres. The maximum amplitude of the m 2 wave occurs just below, and of the m 2 wave just above, cell layer 8 of P. Ramón. The u 1 and u 2 waves are generated by ‘edge’ and ‘convexity’ fibres, respectively. The maximum amplitude of the u 1 wave occurs near the surface of the tectum, and of the u 2 wave some 100 μm below it. Postsynaptic cell bodies for all four classes of optic fibre are located in layer 8.

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