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IOLVIP
The Intraocular Lens for Visually Impaired Patients (IOLVIP or IOL-VIP) is an intraocular lens system aiming to treat patients with poor central vision due to age related macular degeneration. The IOLVIP procedure involves the surgical implantation of a pair of lenses that magnify and divert the image using the principals of the Galilean telescope. By arranging the lenses it is possible to direct the image to a different part of the eye than the fovea Fovea () (Latin for "pit"; plural foveae ) is a term in anatomy. It refers to a pit or depression in a structure. Human anatomy *Fovea centralis of the retina * Fovea buccalis or Dimple * Fovea of the femoral head * Trochlear fovea of the fr ..., which is the centre of the macula and is usually used for detailed vision. The magnified image is projected on to a part of the eye not normally used for detailed vision. Magnification and patient training are both necessary to allow useful vision from this part of the retina. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intraocular Lens
Intraocular lens (IOL) is a lens (optics), lens implanted in the human eye, eye as part of a treatment for cataracts or myopia. If the natural lens is left in the eye, the IOL is known as Phakic intraocular lens, phakic, otherwise it is a pseudophakic, or false lens. Such a lens is typically implanted during cataract surgery, after the eye's cloudy lens (anatomy), natural lens (cataract) has been removed. The pseudophakic IOL provides the same light-focusing function as the natural crystalline lens. The phakic type of IOL is placed over the existing natural lens and is used in refractive surgery to change the eye's optical power as a treatment for myopia (nearsightedness). This is an alternative to LASIK. IOLs usually consist of a small plastic lens with plastic side struts, called haptics, to hold the lens in place in the capsular bag inside the eye. IOLs were conventionally made of an inflexible material (Polymethyl methacrylate, PMMA), although this has largely been superseded ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macular Degeneration
Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), 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. Macular degeneration typically occurs in older people. Genetic factors and smoking also play a role. It is due to damage to the macula of the retina. Diagnosis is by a complete eye exam. The severity is divided into early, intermediate, and late types. The late type is additionally divided into "dry" and "wet" forms with the dry form making up 90% of cases. The difference between the two forms is the change of macula. Those with dry form AMD have drusen, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galilean Telescope
A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope). The refracting telescope design was originally used in spyglasses and astronomical telescopes but is also used for long-focus camera lenses. Although large refracting telescopes were very popular in the second half of the 19th century, for most research purposes, the refracting telescope has been superseded by the reflecting telescope, which allows larger apertures. A refractor's magnification is calculated by dividing the focal length of the objective lens by that of the eyepiece. Refracting telescopes typically have a lens at the front, then a long tube, then an eyepiece or instrumentation at the rear, where the telescope view comes to focus. Originally, telescopes had an objective of one element, but a century later, two and even three element lenses were made. Refracting telescope is a technology that h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fovea Centralis
The fovea centralis is a small, central pit composed of closely packed cones in the eye. It is located in the center of the macula lutea of the retina. The fovea is responsible for sharp central vision (also called foveal vision), which is necessary in humans for activities for which visual detail is of primary importance, such as reading and driving. The fovea is surrounded by the ''parafovea'' belt and the ''perifovea'' outer region. The parafovea is the intermediate belt, where the ganglion cell layer is composed of more than five layers of cells, as well as the highest density of cones; the perifovea is the outermost region where the ganglion cell layer contains two to four layers of cells, and is where visual acuity is below the optimum. The perifovea contains an even more diminished density of cones, having 12 per 100 micrometres versus 50 per 100 micrometres in the most central fovea. That, in turn, is surrounded by a larger peripheral area, which delivers highly com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macula
The macula (/ˈmakjʊlə/) or macula lutea is an oval-shaped pigmented area in the center of the retina of the human eye and in other animals. The macula in humans has a diameter of around and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas. The anatomical macula at a size of is much larger than the clinical macula which, at a size of , corresponds to the anatomical fovea. The macula is responsible for the central, high-resolution, color vision that is possible in good light; and this kind of vision is impaired if the macula is damaged, for example in macular degeneration. The clinical macula is seen when viewed from the pupil, as in ophthalmoscopy or retinal photography. The term macula lutea comes from Latin ''macula'', "spot", and ''lutea'', "yellow". Structure The macula is an oval-shaped pigmented area in the center of the retina of the human eye and other animal eyes. Its center is shifted slightly away from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
