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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, which is the centre of the 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 avas ... 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 i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intraocular Lens
An intraocular lens (IOL) is a lens (optics), lens implanted in the human eye, eye usually as part of a treatment for cataracts or for correcting other vision problems such as myopia, near-sightedness (myopia) and farsightedness, far-sightedness (hyperopia); a form of refractive surgery. If the natural lens is left in the eye, the IOL is known as Phakic intraocular lens, ''phakic'', otherwise it is a ''pseudophakic'' lens (or false lens). Both kinds of IOLs are designed to provide the same light-focusing function as the natural crystalline lens. This can be an alternative to LASIK, but LASIK is not an alternative to an IOL for treatment of cataracts. 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 IOLs were originally made of a rigid material (Poly(methyl methacrylate), PMMA), although this has largely been superseded by the use of flexible materials, such as silicone. Most IOLs ... [...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 vision, blurred or vision loss, no vision in the center of the visual field. Early on there are often no symptoms. 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 release hallucinations, Visual hallucinations may also occur. Macular degeneration typically occurs in older people, and is caused by damage to the macula of retina, macula of the retina. Genetic factors and smoking may play a role. The condition is diagnosed through a complete eye exam. 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 ... [...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 telescopes use technology tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fovea Centralis
The ''fovea centralis'' is a small, central pit composed of closely packed Cone cell, cones in the eye. It is located in the center of the ''macula lutea'' of the retina. The ''fovea'' is responsible for sharp central visual perception, vision (also called foveal vision), which is necessary in humans for activities for which visual detail is of primary importance, such as reading (activity), reading and driving. The fovea is surrounded by the ''parafovea'' belt and the ''perifovea'' outer region. The ''parafovea'' is the intermediate belt, where the Retinal ganglion cell, 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 centra ... [...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. This kind of vision is impaired if the macula is damaged, as 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 the optical axi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
