what does bifocal vision mean
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What are Bifocal Lenses, Intermediate-distance Lenses and Very-close Distance Lenses? 【1】Bifocal Type (Lens for normal daily use) This is a very convenient type of lens that allows the wearer to focus on objects both at close range and in the distance through a single lens and eliminates the irksome need to frequently remove spectacles.
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- Bifocals, the combination of both concave and convex lenses for both types of vision correction, a top lens for distant viewing and a lower lens for reading, were developed around 1760 by the American statesman and inventor Benjamin Franklin.
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- People who have more than one vision problem often need eyeglasses with multifocal lenses. Multifocal lenses, such as bifocals and trifocals, are eyeglass lenses that contain two or more vision-correcting prescriptions.In years past, you could spot a multifocal lens by the line separating the two sections.eople who have more than one vision problem often need eyeglasses with multifocal lenses. Multifocal lenses, such as bifocals and trifocals, are eyeglass lenses that contain two or more vision-correcting prescriptions.
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What are the Different Types of Bifocal Glasses? Bifocals come in three main types that offer varying degrees of transition from the upper and lower lenses. Blended lenses have full strength, or reading strength, at the bottom of the lens. Benjamin Franklin developed the first bifocal glasses. Equal division lenses, segmented bifocals and blended lenses are three main types of bifocal glasses.
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- Bifocals, are eyeglasses with two distinct optical powers, Bifocals are commonly prescribed to people with presbyopia who also require a correction for myopia, hyperopia, and/or astigmatism.
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- Multifocal lenses, however, incorporate both distance- and near-powered lenses into one lens. The lower-powered zones bend light coming from distant objects to a single focal point on the retina. The higher-powered zones bend light from near objects to the same focal point on the retina. Thus, different zones of lens power work together to provide simultaneous near and distance vision.
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What are Bifocal glasses? That's because the lense INSIDE our eye can no longer change shape on demand the way it did when we were younger. Bifocal glasses are a way for your eye doctor to provide you with a tool to help you see at a distance and up close. Bifocal is a compound word, bi meaning two, and focal referring to the focal length. Bifocal glasses have two focal lengths. One focal length allows the wearer to focus at distant objects. The other focal length allows the wearer to focus on closer objects, such as a newspaper or computer screen.
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Bifocals Bifocals can cause headaches and even dizziness in some users. Acclimation to the small field of view offered by the reading segment of bifocals can take some time, as the user learns to move either the head or the reading material rather than the eyes.
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What are Bifocals? Bifocals are a type of prescription eyeglasses designed for people who need both near and farsighted vision correction. Different from single vision lenses, they have two corrective lenses on each side of a pair of glasses, for a total of four lenses per pair. Many people wear single vision corrective lenses for a number of years until their vision changes and they require bifocals for total vision correction.
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Top 20 Doctor insights on: What Causes Wavy Lines In My Vision Vision (Definition). Vision is a feature of a person's brain that allows him to see. He must have normal eyes, optic nerves (that stretch from the eyes to the back of his brain), and visual cortex (the vision center in the brain), in order to see properly. An ophthalmologist is a doctor specializing in vision. ...Read more.
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- Trends of 'bifocals'. Translations for 'bifocals'. British English: bifocals /baɪˈfəʊklz/ NOUN. Bifocals are glasses with lenses made in two halves. The top part is for looking at things some distance away, and the bottom part is for reading and looking at things that are close.
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Progressive Lenses: The Preferred Choice For Presbyopia Correction Instead of having just two or three lens powers like bifocals or trifocals, progressive lenses are true multifocal lenses that provide a seamless progression of many lens powers for all viewing distances. With progressive lenses, you can look up to see clearly across the room and in the distance.
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Amblyopia Amblyopia (from Greek αμβλυωπία, blunt vision), also called lazy eye, is a disorder of sight. It results in decreased vision in an eye that otherwise appears normal, or out of proportion to associated structural problems of the eye. Whenever the brain does not receive visual signals from an eye for a long period of time, there is a risk of amblyopia. It also can occur when the brain turns off the visual processing of one eye to prevent double-vision, for example in strabismus (crossed eyes). The cause of amblyopia is within the brain.
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What are Progressive lenses? This is why progressive lenses are often referred to as no-line bifocals or trifocals. And it's why progressive lenses are ideal for patients who have presbyopia – a vision condition marked by a decrease in the ability to focus sharply on nearby objects. As we age naturally, our ability to see nearby objects and objects in the distance can decrease.
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legal blindness blindness. lack or loss of ability to see (see vision). Legally, blindness is defined as less than 20/200 vision in the better eye with glasses (vision of 20/200 is the ability to see at 20 feet only what the normal eye can see at 200 feet). A person with 20° or less vision (pinhole vision) is also legally blind.
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Binocular disparity Binocular disparity refers to the difference in image location of an object seen by the left and right eyes, resulting from the eyes’ horizontal separation (parallax). The brain uses binocular disparity to extract depth information from the two-dimensional retinal images in stereopsis.
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Lens Types Progressive Lenses. Progressive Lenses are also referred as “no line” or “invisible” bifocals. This kind of lens, in most cases constitutes the preferred type of correction for presbyopia. Progressive Lenses allow you to focus for distance, reading and at intermediate distances. Progressive lenses look more attractive than bifocals by having no lines and improving your appearance.
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monovision monovision. A treatment for presbyopia in which the dominant eye is corrected to improve distance vision and the other eye is corrected for near and intermediate tasks.Standard lenses, contact lenses, or refractive surgery may be used for the corrections.odified monovision is a method of achieving monovision using bifocal contact lenses in which the powers, lens fit or other lens parameters are modified to emphasize distance vision for one eye and near vision for the other eye, while still retaining a reasonable level of binocular vision. 1  Facebook. 2  Twitter.
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Bifocal And Trifocal Options For Vision After Age 40 Although most bifocals and trifocals have visible lines at the border of lens segments, there is a blended round-seg bifocal that has a less noticeable near segment than its regular round-seg cousin. The near seg is blended into the distance portion of the lens so that it is virtually invisible.
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- Eyeglasses with bifocal or progressive addition lenses (PALs) are the most common correction for presbyopia. Bifocal means two points of focus: the main part of the spectacle lens contains a prescription for distance vision, while the lower portion of the lens holds the stronger near prescription for close work.
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Bifocal, Trifocal and Progressive Glasses Bifocal, Trifocal, and Progressive lenses actively counteract the effects of presbyopia by increasing short range focus in specific portions of the lens without changing the focus for distance vision.
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Which Eyeglasses Are Right For You? Bifocal, Progressive or Single-Vision Reading Glasses? If you want to use a pair of bifocals to reconfigure your prescription to get computer vision in the top part of your lens and reading vision in the bottom, do the same thing you would do for single vision computer glasses.
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- A progressive lens is a corrective lens used in eyeglasses to correct presbyopia. A progressive addition lens gradually and seamlessly changes in power to provide clear distance, as well as intermediate and near vision with no visible segments or demarcation lines. Progressive lenses are often referred to as invisible, no-line bifocals. Many people prefer the look of progressive lenses over bifocals, as they appear to be single vision lenses. In other words, nobody will realize that you are wearing bifocals. Also Known As: No-line bifocal, PAL (progressive addition lens ), varifocal lens.
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What are Bifocals? A farsighted person who also has trouble reading may be prescribed a pair of bifocal reading glasses, for example. The upper section of the lens would correct difficulties seeing objects at distance, and the lower section would assist in reading.
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Bifocal And Trifocal Options For Vision After Age 40 Modern Bifocal and Trifocal Lens Options. Today, you can select from many bifocal and trifocal lens designs, depending on your age and visual needs. There are even special bifocals and trifocals designed for glasses for computer work and other tasks that take place at the intermediate range. In the following images, distance describes the area of the lens used for far vision, intermediate for arm's length and near for reading vision (about 16 inches away).
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glasses eyeglasses, specs, spectacles. 1  bifocals - eyeglasses having two focal lengths, one for near vision and the other for far vision. 2  nosepiece, bridge - the link between two lenses; rests on the nose. 3  frame - the framework for a pair of eyeglasses.  goggles - tight-fitting spectacles worn to protect the eyes.