Presbyopia (Greek word "presbyteros" (πρεσβύτερος), meaning "elder") is the eye's diminished ability to focus that occurs with aging. The most widely held theory is that it arises from the loss of elasticity of the crystalline lens, although changes in the lens's curvature from continual growth and loss of power of the ciliary muscles (the muscles that bend and straighten the lens) have also been postulated as its cause. The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) is a coding of diseases and signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or diseases, as classified by the World Health Organization (WHO). ... // H00-H59 - Diseases of the eye and adnexa (H00-H06) Disorders of eyelid, lacrimal system and orbit (H00) Hordeolum and chalazion (H000) Hordeolum and other deep inflammation of eyelid (H001) Chalazion (H01) Other inflammation of eyelid (H010) Blepharitis (H011) Noninfectious dermatoses of eyelid (H02) Other disorders of eyelid (H020) Entropion... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... For other uses, see Eye (disambiguation). ... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ... The ciliary muscle is a smooth muscle that affects zonular fibers in the eye (fibers that suspend the lens in position during accommodation), enabling changes in lens shape for light focusing. ...

Presbyopia is not a disease as such, but a condition that affects everyone at a certain age. The first symptoms are usually noticed between the ages of 40-50, though in fact the ability to focus declines throughout life, from an accommodation of about 20 dioptres (ability to focus at 50 mm away) in a young person to 10 dioptres at 25 and levelling off at 0.5 to 1 dioptre at age 60 (ability to focus down to 1 -2 metres only). For those with good distance vision, it may start with difficulty reading fine print, particularly if the lighting is poor, or with eyestrain when reading for long periods. Many advanced presbyopes complain that their arms have become "too short" to hold reading material at a comfortable distance.^[1] For a forthcoming article on eyeglass prescriptions File links The following pages link to this file: Eyeglass prescription Categories: Images with unknown source ... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ... A dioptre, or diopter, is a non-SI unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres (i. ... ...

In optics, the closest point at which an object can be brought into focus by the eye is called the eye's near point. A standard near point distance of 25 cm is typically assumed in the design of optical instruments, and in characterizing optical devices such as magnifying glasses. For the book by Sir Isaac Newton, see Opticks. ... A magnifying glass is a single convex lens which is used to see girls better it is wonderful i love eating it is so tasty a mg is used also toproduce a magnified image of an object. ...

Presbyopia, like other focus defects, becomes much less noticeable in bright sunlight. This is not the result of any mysterious 'healing effect' but just the consequence of the iris closing to a pinhole, so that depth of focus, regardless of actual ability to focus, is greatly enhanced, as in a pinhole camera which produces images without any lens at all. Another way of putting this is to say that the circle of confusion, or blurredness of image, is reduced, without improving focusing. Principle of a pinhole camera. ... In optics, a circle of confusion, (also known as disk of confusion, circle of indistinctness, blur circle, etc. ...

A delayed onset of seeking correction for presbyopia has been found among those with certain professions and those with miotic pupils.^[2] In particular, farmers and housewives seek correction later, whereas service workers and construction workers seek eyesight correction earlier. A miotic substances causes the constriction of the pupil of the eye ... The human eye The pupil is the central transparent area (showing as black). ...

Focusing mechanism of the eye

There is some confusion in articles and even textbooks over how the focusing mechanism of the eye actually works. In the classic book, 'Eye and Brain' by Gregory, for example, the lens is said to be suspended by a membrane, the 'zonula', which holds it under tension. The tension is released, by contraction of the ciliary muscle, to allow the lens to fatten, for close vision. This would seem to imply that the ciliary muscle, which is outside the zonula must be circumferential, contracting like a sphincter, to slacken the tension of the zonula pulling outwards on the lens. This is consistent with the fact that our eyes seem to be in the 'relaxed' state when focusing at infinity, and also explains why no amount of effort seems to enable a myopic person to see further away. Many texts, though, describe the 'ciliary muscles' (which seem more likely to be just elastic ligaments and not under any form of nervous control) as pulling the lens taut in order to focus at close range.^{[citation needed]} This has the counterintuitive effect of steepening the lens centrally (increasing its power) and flattening peripherally.

Presbyopia and the 'payoff' for the nearsighted

Many people with myopia are able to read comfortably without eyeglasses or contact lenses even after age 40. Myopes considering refractive surgery are advised that surgically correcting their nearsightedness may actually be a disadvantage after the age of 40 when the eyes become presbyopic and lose their ability to accommodate or change focus because they will then need to use glasses for reading. Normal vision. ... Refractive eye surgery is any eye surgery used to improve the refractive state of the eye and decrease dependency on glasses or contact lenses. ... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ...

Treatment

Presbyopia is not routinely curable - though tentative steps toward a possible cure suggest that this may be possible - but the loss of focusing ability can be compensated for by corrective lenses including eyeglasses or contact lenses. In subjects with other refractory problems, Convex lenses are used. In some cases, the addition of bifocals to an existing lens prescription is sufficient. As the ability to change focus worsens, the prescription needs to be changed accordingly. A corrective lens is a prosthetic lens worn on or before the eye, used to treat myopia, hypermetropia, presbyopia and astigmatism. ... Glasses, spectacles, or eyeglasses are frames bearing lenses worn in front of the eyes, sometimes for purely aesthetic reasons but normally for vision correction or eye protection. ... A soft contact lens A contact lens (also known as contact, for short) is a corrective or cosmetic lens placed on the cornea of the eye atop the iris. ... Look up convex in Wiktionary, the free dictionary. ...

Around the age of 65, the eyes have usually lost most of the elasticity. However, it will still be possible to read with the help of the appropriate prescription. Some may find it necessary to hold reading materials farther away, or require larger print and more light to read by. People who do not need glasses for distance vision may only need half glasses or reading glasses.

While bifocals and multifocals offer a working solution to everyday problems, they are hated by many, especially engineers, camera operators, and those used to having a good sharp distortion-free image in their work. Varifocals cause straight lines to look bent, and can leave some feeling dizzy after extended use. The power of simple, multiple prescriptions should not be underestimated. Reading glasses hastily prescribed may be fine for reading, but not good for shopping and generally walking around in. A slightly weaker prescription however, just powerful enough for reading using the full remaining accommodation of the eye, may feel much more comfortable for more general use too. Careful calculation of working ranges, together with a certain amount of trial and error, can restore undistorted vision for critical tasks for many people who do not find multifocals to their liking.

In order to reduce the need for bifocals or reading glasses, some people choose contact lenses to correct one eye for near and one eye for far with a method called "monovision". Monovision sometimes interferes with depth perception. There are also newer bifocal or multifocal contact lenses that attempt to correct both near and far vision with the same lens. ^[3]

Eye exercises have been quoted as a way to delay the onset of Presbyopia. Go to: http://www.cam.org/~rsilver/presben.htm

Surgery

New surgical procedures may also provide solutions for those who do not want to wear glasses or contacts, including the implantation of accommodative intraocular lenses (IOLs). Scleral expansion bands, which increase the space between the ciliary body and lens, have not been found to provide predictable or consistent results in the treatment of presbyopia.^[4] To read more about surgical procedures go to: http://www.allaboutvision.com/visionsurgery/presbyopia_surgery.htm An intraocular lens (IOL) is an implanted lens in the eye, usually replacing the existing crystalline lens because it has been clouded over by a cataract, or as a form of refractive surgery to change the eyes optical power. ...

References

External links

• ReVision Optics, Presbyopia Correction Research
• Correct presbyopia using Conductive Keratoplasty (CK)
• Eyes over 40
• Presbyopia
• Options for today's Presbyopes
• Vision Over 40

Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ...

See also

• Conductive Keratoplasty
• Eye examination
• Astigmatism (eye)
• Eyeglass prescription, especially the section on Distant vision and near vision.
• Hyperopia
• Corrective lens
• Lens (optics)
• Myopia
• Ophthalmology
• Optician
• Optometry
• Bates Method
• Perfect Sight Without Glasses ( chapter 20 )

Source: http://www.nlm.nih.gov/medlineplus/ency/article/001026.htm Conductive keratoplasty (CK) is a type of refractive surgery that uses radio waves to adjust the contour of the cornea by shrinking the corneal collagen around it. ... Traditional Snellen chart used for visual acuity testing. ... Astigmatism is an affliction of the eye, where vision is blurred by an irregularly shaped cornea. ... Using a phoropter to determine a prescription for eyeglasses An eyeglass prescription is a written order by an ophthalmologist or an optometrist to an optician for eyeglasses. ... Using a phoropter to determine a prescription for eyeglasses An eyeglass prescription is a written order by an ophthalmologist or an optometrist to an optician for eyeglasses. ... Hyperopia, also known as hypermetropia or colloquially as farsightedness or longsightedness, is a defect of vision caused by an imperfection in the eye (often when the eyeball is too short or when the lens cannot become round enough), causing inability to focus on near objects, and in extreme cases causing... A bifocal corrective eyeglasses lens A corrective lens is a lens worn on or before the eye, used to treat myopia, hyperopia, astigmatism, and presbyopia. ... A lens. ... Normal vision. ... This article is about the branch of medicine. ... An optician is an individual who makes and adjusts optical aids. ... Optometry (Greek: optos meaning seen or visible and metria meaning measurement) is a health care profession concerned with examination, diagnosis, and treatment of the eyes and related structures and with determination and correction of vision problems using lenses and other optical aids [1]. An optical refractor (also called a foropter... The Bates method is a program created by ophthalmologist William Horatio Bates, M.D., which aims to correct vision habits with relaxation techniques, exercises and optional activities and games. ...