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| Angioid streaks | |
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| Bruchs membrane | |
| Specialty | Ophthalmology  |
Angioid streaks, also called Knapp streaks or Knapp striae are small breaks in Bruch's membrane, an elastic tissue containing membrane of the retina that may become calcified and crack. [1]
Angioid streaks are often associated with pseudoxanthoma elasticum, but have been found to occur in conjunction with other disorders, including Paget's disease, sickle cell disease and Ehlers-Danlos Syndrome. These streaks can have a negative impact on vision due to choroidal neovascularization or choroidal rupture. Also, vision can be impaired if the streaks progress to the fovea and damage the retinal pigment epithelium. The diagnosis is mainly clinical, however fundus fluorescein angiography shows that the streaks appear hyperfluorescent (window defect) in the early phase.
They were first described by Robert Walter Doyne in 1889 in a patient with retinal hemorrhages. A few years later, ophthalmologist Hermann Jakob Knapp called them "angioid streaks" because of their resemblance to blood vessels. From histopathological research in the 1930s, they were discovered to be caused by changes at the level of Bruch's membrane. Presently, it is believed that its pathology may be a combination of elastic degeneration of Bruch's membrane, iron deposition in elastic fibers from hemolysis with secondary mineralization, and impaired nutrition due to stasis and small vessel occlusion.
The retina is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which translates that image into electrical neural impulses to the brain to create visual perception, the retina serving a function analogous to that of the film or image sensor in a camera.
Diabetic retinopathy, also known as diabetic eye disease, is a medical condition in which damage occurs to the retina due to diabetes mellitus. It is a leading cause of blindness in developed countries.
The macula or macula lutea is an oval-shaped pigmented area near the center of the retina of the human eye and some other animalian eyes. The macula in humans has a diameter of around 5.5 mm (0.22 in) and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas.
Vitrectomy is a surgery to remove some or all of the vitreous humor from the eye.
The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye, containing connective tissues, and lying between the retina and the sclera. The human choroid is thickest at the far extreme rear of the eye, while in the outlying areas it narrows to 0.1 mm. The choroid provides oxygen and nourishment to the outer layers of the retina. Along with the ciliary body and iris, the choroid forms the uveal tract.
In visual physiology, adaptation is the ability of the retina of the eye to adjust to various levels of light. Natural night vision, or scotopic vision, is the ability to see under low-light conditions. In humans, rod cells are exclusively responsible for night vision as cone cells are only able to function at higher illumination levels. Night vision is of lower quality than day vision because it is limited in resolution and colors cannot be discerned; only shades of gray are seen. In order for humans to transition from day to night vision they must undergo a dark adaptation period of up to two hours in which each eye adjusts from a high to a low luminescence "setting", increasing sensitivity hugely, by many orders of magnitude. This adaptation period is different between rod and cone cells and results from the regeneration of photopigments to increase retinal sensitivity. Light adaptation, in contrast, works very quickly, within seconds.
Macular degeneration, also known as age-related macular degeneration, is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, some people experience a gradual worsening of vision that may affect one or both eyes. While it does not result in complete blindness, loss of central vision can make it hard to recognize faces, drive, read, or perform other activities of daily life. Visual hallucinations may also occur but these do not represent a mental illness.
Dystrophic calcification (DC) is the calcification occurring in degenerated or necrotic tissue, as in hyalinized scars, degenerated foci in leiomyomas, and caseous nodules. This occurs as a reaction to tissue damage, including as a consequence of medical device implantation. Dystrophic calcification can occur even if the amount of calcium in the blood is not elevated. Basophilic calcium salt deposits aggregate, first in the mitochondria, and progressively throughout the cell. These calcifications are an indication of previous microscopic cell injury. It occurs in areas of cell necrosis in which activated phosphatases bind calcium ions to phospholipids in the membrane.
Central serous retinopathy (CSR), also known as central serous chorioretinopathy, is an eye disease that causes visual impairment, often temporary, usually in one eye. When the disorder is active it is characterized by leakage of fluid under the retina that has a propensity to accumulate under the central macula. This results in blurred or distorted vision (metamorphopsia). A blurred or gray spot in the central visual field is common when the retina is detached. Reduced visual acuity may persist after the fluid has disappeared.
Bruch's membrane is the innermost layer of the choroid. It is also called the vitreous lamina, because of its glassy microscopic appearance. It is 2–4 μm thick.
Metamorphopsia is a type of distorted vision in which a grid of straight lines appears wavy and parts of the grid may appear blank. People can first notice they suffer with the condition when looking at mini-blinds in their home.
Peau d'orange describes anatomy with the appearance and dimpled texture of an orange peel. Peau d'orange is caused by cutaneous lymphatic edema, which causes swelling. However, the infiltrated skin is tethered by the ligament of Cooper such that it cannot swell, leading to an appearance like orange skin. Occasionally, the same phenomenon is seen over a chronic abscess. Examples include the skin of the breast in inflammatory breast cancer, in the eye due to breaks in Bruch's Membrane called angioid streaks, which are common in pseudoxanthoma elasticum, or in elephantiasis caused by thread-like, microscopic parasitic worms (filariasis). Peau d'orange can be also seen with myxedema of Grave's disease, where the term refers more to the texture than the color.
Eales disease is a type of obliterative vasculopathy, also known as angiopathia retinae juvenilis, periphlebitis retinae, primary perivasculitis of the retina. It was first described by the British ophthalmologist Henry Eales (1852–1913) in 1880 and is a rare ocular disease characterized by inflammation and possible blockage of retinal blood vessels, abnormal growth of new blood vessels (neovascularization), and recurrent retinal and vitreal hemorrhages. This disease is identified by its three characteristic steps: vasculitis, occlusion, and retinal neovascularization, leading to recurrent vitreous hemorrhages and vision loss. Eales Disease with a characteristic clinical picture, fluorescein angiographic finding, and natural course is considered a specific disease entity. The exact cause of this disease is unknown but it appears to affect individuals that are from Asian subcontinents. This disease tends to begin between the ages of 20-30 years and begins with unilateral peripheral retinal perivasculitis and peripheral retinal capillary non-perfusion. These are not normally recognized until the inflammation results in vitreous hemorrhage. This disease has been found to affect the second eye 50-90% of the time so there is a large chance that both eyes will begin to show signs of the disease.
Presumed ocular histoplasmosis syndrome (POHS) is a syndrome affecting the eye, which is characterized by peripheral atrophic chorioretinal scars, atrophy or scarring adjacent to the optic disc and maculopathy.
Papillorenal syndrome, is an autosomal dominant genetic disorder marked by underdevelopment (hypoplasia) of the kidney and colobomas of the optic nerve.
Optic disc drusen (ODD) are globules of mucoproteins and mucopolysaccharides that progressively calcify in the optic disc. They are thought to be the remnants of the axonal transport system of degenerated retinal ganglion cells. ODD have also been referred to as congenitally elevated or anomalous discs, pseudopapilledema, pseudoneuritis, buried disc drusen, and disc hyaline bodies.
Robert Walter Doyne (1857–1916) was a British ophthalmologist.
Choroidal neovascularization (CNV) is the creation of new blood vessels in the choroid layer of the eye. Choroidal neovascularization is a common cause of neovascular degenerative maculopathy commonly exacerbated by extreme myopia, malignant myopic degeneration, or age-related developments.
White dot syndromes are inflammatory diseases characterized by the presence of white dots on the fundus, the interior surface of the eye. The majority of individuals affected with white dot syndromes are younger than fifty years of age. Some symptoms include blurred vision and visual field loss. There are many theories for the etiology of white dot syndromes including infectious, viral, genetics and autoimmune.
Vitreomacular adhesion (VMA) is a human medical condition where the vitreous gel of the human eye adheres to the retina in an abnormally strong manner. As the eye ages, it is common for the vitreous to separate from the retina. But if this separation is not complete, i.e. there is still an adhesion, this can create pulling forces on the retina that may result in subsequent loss or distortion of vision. The adhesion in of itself is not dangerous, but the resulting pathological vitreomacular traction (VMT) can cause severe ocular damage.
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