Aniridia—Epidemiology and Genetics

2010 ◽  
Author(s):  
Anil K. Mandal ◽  
Harsha B. L. Rao
Keyword(s):  
Optic Nerve ◽  
Anterior Chamber ◽  
Blood Vessels ◽  
Front Part ◽  
Clear Vision ◽  
Foveal Hypoplasia ◽  
Almost All ◽  
Electric Signals ◽  
The Brain ◽  
Functional Problems

Aniridia literally means “without iris.” The iris is the part of the eye that gives color to the eye. But the term aniridia encompasses more than its literal meaning and includes abnormalities of almost all the structures of the eye, from the cornea up to the optic nerve and including the angle of the anterior chamber, the lens, and the fovea. This is why aniridia is often called a “panocular disease.” The cornea is normally an avascular (lacking blood vessels), transparent tissue on the front part of the eye. In individuals with aniridia, it becomes vascularised. A bunch of blood vessels grows over the cornea: this growth is called a pannus. The angle of the anterior chamber is that part of the eye between the cornea and the iris that drains the fluid within the eye out of the eye and maintains the pressure within the eye at normal levels. Aniridia affects this part and hampers the fluid flow out of the eye, thereby increasing the pressure within the eye, leading to a condition called glaucoma. The lens is a biconvex structure behind the iris that focuses light rays entering into the eye onto the retina, which converts these light signals into electric signals that are carried through the optic nerve to the brain. In aniridia there may be displacement of the lens from its normal position, which is called subluxation or dislocation, or the normally clear lens may turn opaque, which is called a cataract. The fovea is the area of the retina that is responsible for clear vision. It may be underdeveloped; this is called foveal hypoplasia and affects vision. Similarly, the optic nerve that carries the visual sensations may also be underdeveloped, affecting vision. Besides these anatomical abnormalities, functional problems in addition to decreased vision include nystagmus (involuntary wobbling movement of the eye), squinting, and intolerance to light (photophobia). In this chapter we will discuss mainly the epidemiology (incidence and distribution of diseases) and genetic aspects of aniridia.

scholarly journals Retinal Changes in Cerebral Malaria among Sudanese patient in Khartoum State, Sudan 2019

2020 ◽  
pp. 15-18
Author(s):  
Abbasher Hussien ◽  
Khabab Abbasher ◽  
Radi Tofaha Alhusseini ◽  
Mohammed Hamad Malik Al-Dar ◽  
Yousif F.O. Altayeb ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Red Blood Cells ◽  
Cerebral Malaria ◽  
Blood Vessels ◽  
Blood Cells ◽  
Neurological Manifestations ◽  
Cross Sectional ◽  
Infected Blood ◽  
Malarial Retinopathy ◽  
The Brain

Introduction: It is thought that Malaria parasites live in red blood cells and make them stick to the inside of small blood vessels, particularly in the brain and also the eye. The light-sensitive tissue in the eye is also affected because the parasites disrupt the supply of oxygen and nutrients These changes, known as malarial retinopathy, include white, opaque patches, whitening of the infected blood vessels, bleeding into the retina and swelling of the optic nerve. Objectives: Our study was aimed to demonstrate malarial retinopathy in patients presented with neurological manifestations of malaria. Methodology: A cross-sectional Hospital based study included all patients with malaria seen during the period between 1-1-2019 and 25-4-2019

Types of refractive errors and methods for their diagnosis

2020 ◽  
pp. 30-36
Author(s):  
Olga Lemzyakova
Keyword(s):  
Optical System ◽  
Contact Lenses ◽  
Vision Impairment ◽  
Refractive Errors ◽  
Vision Correction ◽  
Light Rays ◽  
Different Types ◽  
Almost All ◽  
Degrees Of Severity ◽  
The Brain

Refraction of the eye means its ability to bend (refract) light in its own optical system. In a normal state, which is called emmetropia, light rays passing through the optical system of the eye focus on the retina, from where the impulse is transmitted to the visual cortex of the brain and is analyzed there. A person sees equally well both in the distance and near in this situation. However, very often, refractive errors develop as a result of various types of influences. Myopia, or short-sightedness, occurs when the light rays are focused in front of the retina as a result of passing through the optical system of the eye. In this case, a person will clearly distinguish close objects and have difficulties in seeing distant objects. On the opposite side is development of farsightedness (hypermetropia), in which the focusing of light rays occurs behind the retina — such a person sees distant objects clearly, but outlines of closer objects are out of focus. Near vision impairment in old age is a natural process called presbyopia, it develops due to the lens thickening. Both myopia and hypermetropia can have different degrees of severity. The variant, when different refractive errors are observed in different eyes, is called anisometropia. In the same case, if different types of refraction are observed in the same eye, it is astigmatism, and most often it is a congenital pathology. Almost all of the above mentioned refractive errors require correction with spectacles or use of contact lenses. Recently, people are increasingly resorting to the methods of surgical vision correction.

scholarly journals Endocrine Dysfunction in Children with Zika-Related Microcephaly Who Were Born during the 2015 Epidemic in the State of Pernambuco, Brazil

Viruses ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 1
Author(s):  
Andréia Veras Gonçalves ◽  
Demócrito de B. Miranda-Filho ◽  
Líbia Cristina Rocha Vilela ◽  
Regina Coeli Ferreira Ramos ◽  
Thalia V. B. de Araújo ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Viral Infections ◽  
Case Series ◽  
Optic Nerve Hypoplasia ◽  
Endocrine Dysfunction ◽  
Careful Monitoring ◽  
Early Puberty ◽  
Growth Impairment ◽  
Appropriate Treatment ◽  
The Brain

Congenital viral infections and the occurrence of septo-optic dysplasia, which is a combination of optic nerve hypoplasia, abnormal formation of structures along the midline of the brain, and pituitary hypofunction, support the biological plausibility of endocrine dysfunction in Zika-related microcephaly. In this case series we ascertained the presence and describe endocrine dysfunction in 30 children with severe Zika-related microcephaly from the MERG Pediatric Cohort, referred for endocrinological evaluation between February and August 2019. Of the 30 children, 97% had severe microcephaly. The average age at the endocrinological consultation was 41 months and 53% were female. The most frequently observed endocrine dysfunctions comprised short stature, hypothyroidism, obesity and variants early puberty. These dysfunctions occurred alone 57% or in combination 43%. We found optic nerve hypoplasia (6/21) and corpus callosum hypoplasia (20/21). Seizure crises were reported in 86% of the children. The most common—and clinically important—endocrine dysfunctions were pubertal dysfunctions, thyroid disease, growth impairment, and obesity. These dysfunctions require careful monitoring and signal the need for endocrinological evaluation in children with Zika-related microcephaly, in order to make early diagnoses and implement appropriate treatment when necessary.

Perivascular (Virchow–Robin) spaces

2021 ◽  
pp. 86-89
Keyword(s):  
Blood Vessels ◽  
Shape Change ◽  
Lymphatic Drainage ◽  
Brain Regions ◽  
Mechanical Trauma ◽  
Normal Brain ◽  
Perivascular Spaces ◽  
Mr Images ◽  
Lenticulostriate Artery ◽  
The Brain

Perivascular spaces; also known as the Virchow-Robin Spaces, they are pleurally lined, interstitial fluid-filled areas that surround certain blood vessels in various organs, especially the perforating arteries in the brain, with an immunological function. Dilated perivascular spaces are divided into three types. The first of these is on the lenticulostriate artery, the second is in the cortex following the path of the medullary artery, and the third is in the midbrain. Perivascular spaces can be detected as areas of dilatation on MR images. Although a limited number of perivascular spaces can be seen in a normal brain, the increase in the number of these spaces has been associated with the incidence of various neurodegenerative diseases. Different theories have been suggested about the tendency of the perivascular spaces to expand. Current theories include mechanical trauma due to cerebrospinal fluid pulsing, elongation of penetrating blood vessels, unusual vascular permeability, and increased fluid exudation. In addition, the brain tissue atrophy that occurs with aging; It is thought to contribute to the widening of perivascular spaces by causing shrinkage of arteries, altered arterial wall permeability, obstruction of lymphatic drainage pathways and vascular demyelination. It is assumed that the clinical significance of the dilation tendencies of the perivascular spaces is based on shape change rather than size. These spaces have been mostly observed in brain regions such as corpus callosum, cingulate gyrus, dentate nucleus, substantia nigra and various arterial basins including lenticulostriate artery and mesencephalothalamic artery. In conclusion, when sections are taken on MR imaging, it is possible that perivascular spaces may be confused with microvascular diseases and some neurodegenerative changes. In addition, perivascular spaces can be seen without pathological significance. Therefore, it would be appropriate to investigate the etiological relationship by evaluating the radiological findings and clinical picture together.

Analysis of Changes in Signal Intensity of Choroid Plexus in MRI Using FLAIR-DW-EPI Pulse Sequence

2020 ◽  
Vol 3 (1) ◽  
pp. 9-15
Author(s):  
Jingyu Kim ◽  
◽  
Sang-Jin Im ◽  
Keyword(s):  
Choroid Plexus ◽  
Signal Intensity ◽  
Pulse Sequence ◽  
Signal Strength ◽  
Brain Parenchyma ◽  
Weighted Image ◽  
Diffusion Weighted ◽  
Water Signal ◽  
The Brain ◽  
Functional Problems

In this study, the signal intensity of choroid plexus, which is producing cerebrospinal fluid, is analyzed according to the FLAIR diffusion-weighted imaging technique. In the T2*-DW-EPI diffusion-weighted image, the FLAIR-DW-EPI technique, which suppressed the water signal, was additionally examined for subjects with high choroid plexus signals and compared and analyzed the signal intensity. As a result of the experiment, it was confirmed that the FLAIR-DW-EPI technique showed a signal strength equal to or lower than that of the brain parenchyma, and there was a difference in signal strength between the two techniques. As a result of this study, if the choroidal plexus signal is high in the T2 * -DW-EPI diffusionweighted image, additional examination of the FLAIR-DW-EPI technique is thought to be useful in distinguishing functional problems of the choroid plexus. In conclusion, if the choroidal plexus signal is high on the T2*-DW-EPI diffuse weighted image, it is thought that further examination of the FLAIR-DW-EPI technique will be useful in distinguishing functional problems of the choroidal plexus.

Two Cases of Atheroma of the Blood Vessels at the Base of the Brain, with Remarks upon the Symptoms, Diagnosis, Prognosis, and Pathological Condition in that Affection

1870 ◽  
Vol 16 (73) ◽  
pp. 52-58
Author(s):  
J. T. Sabben
Keyword(s):  
Blood Vessels ◽  
Pathological Condition ◽  
Cerebral Arteries ◽  
General Paralysis ◽  
Brain Substance ◽  
The Brain

In publishing the following cases, recently under my charge, of mental derangement dependent upon atheromatous deposit in the coats of the larger cerebral arteries, without any apparent disease of the brain substance, I desire, if possible, to define the symptoms of that condition during life, so as to enable them to be distinguished from those of general paralysis, with which I believe them often to be confused.

scholarly journals Photoreceptive retinal ganglion cells control the information rate of the optic nerve

2018 ◽  
Vol 115 (50) ◽  
pp. E11817-E11826 ◽  
Author(s):  
Nina Milosavljevic ◽  
Riccardo Storchi ◽  
Cyril G. Eleftheriou ◽  
Andrea Colins ◽  
Rasmus S. Petersen ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Retinal Ganglion Cells ◽  
Information Flow ◽  
Information Transfer ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Ambient Light ◽  
Visual Responses ◽  
Light Irradiance ◽  
The Brain

Information transfer in the brain relies upon energetically expensive spiking activity of neurons. Rates of information flow should therefore be carefully optimized, but mechanisms to control this parameter are poorly understood. We address this deficit in the visual system, where ambient light (irradiance) is predictive of the amount of information reaching the eye and ask whether a neural measure of irradiance can therefore be used to proactively control information flow along the optic nerve. We first show that firing rates for the retina’s output neurons [retinal ganglion cells (RGCs)] scale with irradiance and are positively correlated with rates of information and the gain of visual responses. Irradiance modulates firing in the absence of any other visual signal confirming that this is a genuine response to changing ambient light. Irradiance-driven changes in firing are observed across the population of RGCs (including in both ON and OFF units) but are disrupted in mice lacking melanopsin [the photopigment of irradiance-coding intrinsically photosensitive RGCs (ipRGCs)] and can be induced under steady light exposure by chemogenetic activation of ipRGCs. Artificially elevating firing by chemogenetic excitation of ipRGCs is sufficient to increase information flow by increasing the gain of visual responses, indicating that enhanced firing is a cause of increased information transfer at higher irradiance. Our results establish a retinal circuitry driving changes in RGC firing as an active response to alterations in ambient light to adjust the amount of visual information transmitted to the brain.

scholarly journals Meningeal Tumors Induced in Calves with the Bovine Cutaneous Papilloma Virus

1969 ◽  
Vol 6 (2) ◽  
pp. 135-145 ◽  
Author(s):  
D. F. Brobst ◽  
G. C. Dulac
Keyword(s):  
Blood Vessels ◽  
Viral Antigen ◽  
Papilloma Virus ◽  
Meningeal Tumors ◽  
The Brain

Fibromatous tumors were induced in the meninges of calves by inoculating the meninges with a suspension of bovine cutaneous papillomas or by implanting bovine cutaneous papillomas into the brain. Meningeal tumors were observed to occur as early as 20 days after inoculation. Meningeal tumors from calves killed 90 and 145 days after inoculation extended into the brain along the course of blood vessels. Metastasis, however, was not observed. Evidence that the induced meningeal tumors contained viral antigen was lacking.

scholarly journals Ocular, Neurologic and Systemic Findings of the Cases with Optic Nerve Hypoplasia

2016 ◽  
Vol 10 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Eyyup Karahan ◽  
Ayse Tulin Berk
Keyword(s):  
Optic Nerve ◽  
Chart Review ◽  
Retrospective Chart Review ◽  
Optic Nerve Hypoplasia ◽  
Refractive Errors ◽  
Poor Vision ◽  
The Relationship ◽  
The Brain ◽  
Ocular Signs ◽  
Neurologic Findings

Aim: To describe the associated ocular, neurologic, and systemic findings in a population of children with optic nerve hypoplasia (ONH) and to evaluate the relationship between ocular signs and neurologic findings. Method: A retrospective chart review of 53 patients with the diagnosis of ONH seen between December 1998 and September 2012 was performed. All neurodevelopmental anomalies, neuroradiologic findings, endocrinologic and systemic findings were recorded. Poor vision was defined as the visual acuity poorer than logMAR 1.0 or inadequate central steady maintained fixation. Results: Thirty (56.6%) of the 53 children with ONH were boys. Mean age at presentation was 56.2±46.8 months (range; 3 months to 18 years). Poor vision defined for the purpose of this study was found in 47.2% of 53 patients. Thirty-three (62.3%) children had nystagmus. Thirty-four (64.2%) children had strabismus. Thirteen (38.2%) of those with strabismus had esotropia, 20 (58.8%) had exotropia. The total number of the children with neurodevelopmental deficit was 22 (41.5%) in our study. Conclusion: The vision of young children with ONH should be monitored at least annually, and any refractive errors should be treated. Neuroimaging of the brain and endocrinologic evaluation is necessary in all cases with ONH.

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