Difference between revisions of "Presbyopia" - New World Encyclopedia

**Presbyopia**
[[Image:{{{Image}}}\|190px\|center\|]];
ICD-10	H52.4
ICD-O:	{{{ICDO}}}
ICD-9	367.40
OMIM	{{{OMIM}}}
MedlinePlus	{{{MedlinePlus}}}
eMedicine	{{{eMedicineSubj}}}/{{{eMedicineTopic}}}
DiseasesDB	{{{DiseasesDB}}}

Revision as of 00:32, 9 August 2008

Presbyopia (Greek word "presbys" (πρέσβυς), meaning "old person") describes the condition where the eye exhibits a progressively diminished ability to focus on near objects with age. Presbyopia's exact mechanisms are not known with certainty, however, the research evidence most strongly supports a 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.

Similar to grey hair and wrinkles, presbyopia is a symptom caused by the natural course of aging. The first symptoms (described below) are usually first noticed between the ages of 40-50. The ability to focus on near objects declines throughout life, from an accommodation of about 20 dioptres (ability to focus at 50 mm away) in a child to 10 dioptres at 25 (100 mm) and leveling off at 0.5 to 1 dioptre at age 60 (ability to focus down to 1-2 meters only).

Symptoms

The first symptoms most people notice are, difficulty reading fine print, particularly in low light conditions, eyestrain when reading for long periods, blur at near or momentarily blurred vision when transitioning between viewing distances. Many advanced presbyopes complain that their arms have become "too short" to hold reading material at a comfortable distance.^[1]

Presbyopia, like other focus defects, becomes much less noticeable in bright sunlight. This is a result 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.

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.

Focusing mechanism of the eye

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.

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. However, their myopia does not disappear and the long-distance visual challenges will remain. Myopes with astigmatism will find near vision better though not perfect without glasses or contact lenses once presbyopia sets in, but the greater the amount of astigmatism the poorer their uncorrected near vision. 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. A surgical technique offered is to create a "reading eye" and a "distance vision eye", a technique commonly used in contact lens practice, known as monovision.

Treatment

Template:Cleanup-section Template:Advert 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.

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].

Controversially, eye exercises have been quoted as a way to delay the onset of Presbyopia [1].

Nutrition

At least one scientific study reported that taking lutein supplements or otherwise increasing the amount of lutein in the diet resulted in an improvement in visual acuity,^[4] while another study suggested that lutein supplementation might slow aging of the lens.^[5] Lutein is found naturally in both the lens of the eye and the macula, the central area of the retina.

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.^[6]

References
ISBN links support NWE through referral fees

↑ Robert Abel, The Eye Care Revolution: Prevent and Reverse Common Vision Problems, Kensington Books, 2004.
↑ Garcia Serrano JL, Lopez Raya R, Mylonopoulos Caripidis T. "Variables related to the first presbyopia correction." Arch Soc Esp Oftalmol. 2002 Nov;77(11):597-604. PMID 12410405.
↑ Guoqiang Li et al, Switchable electro-optic diffractive lens with high efficiency for ophthalmic applications", Proceedings of National Academy of Sciences USA, V103, 6100-6104 (2006).
↑ Nutrition Volume 19, Issue 1, pp. 21-24. Retrieved 2008-04-14.
↑ Lens Aging in Relation to Nutritional Determinants and Possible Risk Factors for Age-Related Cataract. Retrieved 2008-04-15.
↑ Malecaze FJ, Gazagne CS, Tarroux MC, Gorrand JM. "Scleral expansion bands for presbyopia." Ophthalmology. 2001 Dec;108(12):2165-71. PMID 11733253.

External links

Credits

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Presbyopia ^history

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History of "Presbyopia"

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[1] Robert Abel, The Eye Care Revolution: Prevent and Reverse Common Vision Problems, Kensington Books, 2004.

[Garcia-2] Garcia Serrano JL, Lopez Raya R, Mylonopoulos Caripidis T. "Variables related to the first presbyopia correction." Arch Soc Esp Oftalmol. 2002 Nov;77(11):597-604. PMID 12410405.

[3] Guoqiang Li et al, Switchable electro-optic diffractive lens with high efficiency for ophthalmic applications", Proceedings of National Academy of Sciences USA, V103, 6100-6104 (2006).

[4] Nutrition Volume 19, Issue 1, pp. 21-24. Retrieved 2008-04-14.

[5] Lens Aging in Relation to Nutritional Determinants and Possible Risk Factors for Age-Related Cataract. Retrieved 2008-04-15.

[6] Malecaze FJ, Gazagne CS, Tarroux MC, Gorrand JM. "Scleral expansion bands for presbyopia." Ophthalmology. 2001 Dec;108(12):2165-71. PMID 11733253.

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[2]

[3]

[4]

[5]

[6]

@@ Line 1: / Line 1: @@
+{{DiseaseDisorder infobox |
+  Name        = Presbyopia |
+  ICD10      = {{ICD10|H|52|4|h|49}} |
+  ICD9        = {{ICD9|367.40}} |
+}}
-==PRESBYOPIA==
+'''Presbyopia''' (Greek word "presbys" (πρέσβυς), meaning "old person") describes the condition where the [[eye]] exhibits a progressively diminished ability to focus on near objects with age. Presbyopia's exact mechanisms are not known with certainty, however, the research evidence most strongly supports a loss of elasticity of the [[Lens (vision)|crystalline lens]], although changes in the lens's curvature from continual growth and loss of power of the [[ciliary muscle]]s (the muscles that bend and straighten the lens) have also been postulated as its cause.
-Presbyopia is an eye condition associated with aging. It’s common among people who fall under the age group between 40 and 50 years.
+[[Image:Specrx-accom.png|right]]
-Usually, when you switch from looking at something at a distance to something up close, the lens in your eye changes shape in order to focus on the close object. With age, the lens loses its elastic qualities and hence the ability to clearly see small things up close. Fine objects close to you look blurred. Although this condition gradually worsens, it does not cause blindness and can easily be corrected with bifocals or reading glasses. It is not the same thing as farsightedness.
+Similar to grey hair and wrinkles, presbyopia is a symptom caused by the natural course of aging. The first symptoms (described below) are usually first noticed between the ages of 40-50. The ability to focus on near objects declines throughout life, from an [[accommodation (eye)|accommodation]] of about 20 [[dioptre]]s (ability to focus at 50 mm away) in a child to 10 dioptres at 25 (100 mm) and leveling off at 0.5 to 1 dioptre at age 60 (ability to focus down to  1-2 meters only).
+==Symptoms==
-==Causes==
+The first symptoms most people notice are, difficulty reading fine print, particularly in low light conditions, [[asthenopia|eyestrain]] when reading for long periods, blur at near or momentarily blurred vision when transitioning between viewing distances. Many advanced presbyopes complain that their arms have become "too short" to hold reading material at a comfortable distance.<ref>Robert Abel, ''The Eye Care Revolution: Prevent and Reverse Common Vision Problems'', Kensington Books, 2004.</ref>
-People with no refractive error tend to notice presbyopia in their mid-40s. Whereas people with farsightedness detect presbyopia earlier, especially when they are not wearing their glasses.
+Presbyopia, like other focus defects, becomes much less noticeable in bright sunlight. This is a result 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.
-Though it’s largely an age related condition and affects alomost everyone, other conditions like diabetes can result in an earlier onset of presbyopia.
+A delayed onset of seeking correction for presbyopia has been found among those with certain professions and those with [[miotic]] [[pupil]]s.<ref name="Garcia">Garcia Serrano JL, Lopez Raya R, Mylonopoulos Caripidis T. "Variables related to the first presbyopia correction." ''Arch Soc Esp Oftalmol.'' 2002 Nov;77(11):597-604. PMID 12410405.</ref>  In particular, farmers and housewives seek correction later, whereas service workers and construction workers seek eyesight correction earlier.
+==Focusing mechanism of the eye==
-==Signs & Symptoms==
+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&nbsp;cm is typically assumed in the design of optical instruments, and in characterizing optical devices such as [[magnifying glass]]es.
-Difficulty in reading fine print up close is the most common indicator, besides decreased focusing ability, eyestrain and frequent headaches.
+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.{{Fact|date=February 2007}} This has the counterintuitive effect of steepening the lens centrally (increasing its power) and flattening peripherally.
-People with presbyopia must hold reading material farther from their eyes. Nearsighted people may need to take off their distance glasses to read. So if you have trouble reading the newspaper or threading a needle, it’s time to see a doctor.
+==Presbyopia and the 'payoff' for the nearsighted==
-Another symptom of early presbyopia is when distance vision stays blurred a few moments after a person looks up from reading. The symptoms become worse with fatigue.
-==Diagnosis==
-The reading card is the most basic test for presbyopia. The patient reads a card with various sized letters and numbers, held 14 or 16 inches away. The patient is then allowed to try different lenses to ascertain what correction is needed.
-This is followed by a general eye examination and tests to determine various measurements:
-*Visual acuity test
-*Refraction test
-*Muscle integrity test
-*Slit-lamp test
-*Retinal examination
+Many people with [[myopia]] are able to read comfortably without eyeglasses or contact lenses even after age 40. However, their myopia does not disappear and the long-distance visual challenges will remain. Myopes with [[Astigmatism (eye)|astigmatism]] will find near vision better though not perfect without glasses or contact lenses once presbyopia sets in, but the greater the amount of astigmatism the poorer their uncorrected near vision. 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 [[accommodation (eye)|accommodate]] or change focus because they will then need to use glasses for reading. A surgical technique offered is to create a "reading eye" and a "distance vision eye", a technique commonly used in contact lens practice, known as monovision.
 ==Treatment==
+{{Cleanup-section|date=August 2008}}
+{{advert|section}}
+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.
-People diagnosed with presbyopia need not go in for correction immediately after symptoms begin, at least for a year or two. Some simple steps can help ease the reading difficulty, like:
-*Changing the reading distance
+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.
-*Increasing illumination
+<ref>Guoqiang Li et al, ''Switchable electro-optic diffractive lens with high efficiency for ophthalmic applications", Proceedings of National Academy of Sciences USA, V103, 6100-6104 (2006).</ref>.
-*Taking frequent breaks while reading
-*If nearsighted, removing the regular glasses to read
-Correction of presbyopia would involve compensating for the lost accommodative power of the lens of the eye. This is achieved by using a plus lens, which is quite similar to a magnifying lens. And as the lens of the eye continues to change with age, upgrading to a stronger reading glass is required every two years until the mid-50s or 60s. Little change is needed after that, provide that other visual problem don’t develop.
+Controversially, eye exercises have been quoted as a way to delay the onset of Presbyopia [http://www.cam.org/~rsilver/presben.htm].
-Several options are available for correcting presbyopia. For most, reading glasses would do the job. Here the whole lens of the eyeglass contains the necessary correction for reading. Which lets you see close objects clearly, but makes distant objects look blurred. For that reason, reading glasses must be removed to see objects in the distance. These glasses are recommended for those who don’t mind switching between two glasses – for reading and otherwise, those who don’t need distance correction and for those who wear contact lenses for distance vision. They are also prescribed for people who cannot wear bifocals.
+;Nutrition
-Reading glasses can be obtained with or without a prescription. Over-the-counter glasses are also available and they cost much less than custom-made glasses. Even the readymade type of glasses is very effective and suits most patients.
+At least one scientific study reported that taking [[lutein]] supplements or otherwise increasing the amount of lutein in the diet resulted in an improvement in [[visual acuity]],<ref>
+{{cite web
+| url = http://www.nutritionjrnl.com/article/S0899-9007(02)00861-4/abstract
+| title = Nutrition Volume 19, Issue 1, pp. 21-24
+| accessdate = 2008-04-14
+}}</ref> while another study suggested that lutein supplementation might slow aging of the lens.<ref>
+{{cite web
+| url = http://archopht.ama-assn.org/cgi/content/abstract/120/12/1732
+| title = Lens Aging in Relation to Nutritional Determinants and Possible Risk Factors for Age-Related Cataract
+| accessdate = 2008-04-15
+}}</ref> Lutein is found naturally in both the lens of the eye and the [[macula]], the central area of the [[retina]].
-People who do not need glasses for distance vision may only need half glasses or reading glasses. Half-glasses leave the top of the glasses open to facilitate distance vision without the need to remove the glasses.
+===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 lens]]es (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.<ref>Malecaze FJ, Gazagne CS, Tarroux MC, Gorrand JM. "Scleral expansion bands for presbyopia." ''Ophthalmology.'' 2001 Dec;108(12):2165-71. PMID 11733253.</ref>
-Then there are bifocals, which have two lenses in one. One segment, usually the one at the bottom, is made to adjust the eye for close focus, and the other one has a different strength for distant focus. Wearing bifocals require patients to make some adjustments, as they need to learn to automatically look through the proper part of the glass.
-Images through the lower segment look like they are in a slightly different place than they really are. As the plus segment magnifies objects, things appear closer to the wearer than they really are. Walking down stairs may be difficult until the person learns to hold a different head position. And as the eyes cross the junction of the distance and near segments, the image jumps up for a split second. Some styles of bifocal lenses can lessen this image jump.
-But after the initial problems of getting used to the glasses, most people find bifocals quite convenient. And for people concerned about their appearance, invisible bifocals or bifocal contact lenses may also be an option.
-Invisible bifocals are glasses that don’t have a visible line dividing the upper and lower segments. These seamless bifocals have the segment line polished so that it is not visible as a distinct line. In the area where both the segments blend, some blurry vision results. This means the wearer experiences more difficulty getting adjusted.
-Patients can also opt for a progressive addition lens or variable-power lens. This has no visible line either. This acts like a trifocal lens that provides clear vision for far distance, intermediate distance and short distances as well. But, unlike bifocals or trifocals, it has a gradual change in power over the area of the lens. With this, objects below the line of direct vision and to the side are somewhat blurred. Progressive addition lenses often take longer to adjust to and may cost more than bifocals.
-Contact lenses can be used to correct one eye for near vision and one eye for far vision. This is termed “monovision”. It eliminates the need for bifocals or reading glasses, but can interfere with depth perception.
-Contact lenses that can correct for both near and far vision with the same lens are also prescribed for some. But bifocal contact lenses aren’t as successful as conventional single-vision contact lenses and some find it extremely inconvenient. The problems associated with bifocal lenses are fluctuating distance vision and poor near vision. But those opting for contact lenses find better image quality with rigid gas- permeable lenses than hydrogel (soft) bifocals.
-Trifocals are prescribed for people with difficulty seeing clearly at an intermediate distance (3-5 feet away) with bifocals. These lenses have a middle section to correct vision for midrange distances. A person wearing trifocals looks through the top segment to see distant objects, through the middle to see just past arm’s length and through the bottom to see close objects.
-For choosing the right kind of reading glasses, it is important to take into consideration the patient’s occupation, hobbies and visual needs.
-There are some new surgical procedures that patients can explore, to do away with wearing glasses or contacts.
 ==References==
-Retrieved from:
+<div class="references-small">
+<!--See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for an explanation of how to generate footnotes using the <ref(erences/)> tags—>
+<references/>
+</div>
-• “http://adsabs.harvard.edu”
+==External links==
+{{Wiktionarypar|presbyopia}}
+*[http://www.ckvisioncare.co.uk/HumanEye.aspx Correct presbyopia using Conductive Keratoplasty (CK)]
+*[http://www.allaboutvision.com/over40/ Eyes over 40]
+*[http://www.eyetopics.com/articles/48/1/Presbyopia Presbyopia]
+*[http://www.eyetopics.com/articles/90/1/Options-for-todays-Presbyopes Options for today's Presbyopes]
+*[http://www.visionover40.com Vision Over 40]
+*[http://www.nlm.nih.gov/medlineplus/ency/article/001026.htm Presbyopia at MedLinePlus Medical Encyclopedia]
-• “http://lasik.wustl.edu”
+== See also ==
+*[[Conductive keratoplasty|Conductive Keratoplasty]]
+*[[Eye examination]]
+*[[Astigmatism (eye)]]
+*[[Eyeglass prescription]], especially the section on [[Eyeglass prescription#Distant vision and near vision|Distant vision and near vision]].
+*[[Hyperopia]]
+*[[Corrective lens]]
+*[[Lens (optics)]]
+*[[Myopia]]
+*[[Ophthalmology]]
+*[[Optician]]
+*[[Optometry]]
-• “http://www.uic.edu”
+{{Eye pathology}}
-• “http://www.nlm.nih.gov”
+[[Category:Life sciences]]
+[[Category:Health and disease]]
+[[Category:Diseases]]
-[[Category:Life sciences]]
+{{credit|Presbyopia|230396550}}
-{{credit|133580419}}

Pathology of the eye (primarily H00-H59)
Eyelid, lacrimal system and orbit	Stye - Chalazion - Blepharitis - Entropion - Ectropion - Lagophthalmos - Blepharochalasis - Ptosis - Xanthelasma - Trichiasis - Dacryoadenitis - Epiphora - Exophthalmos - Enophthalmos
Conjunctiva	Conjunctivitis - Pterygium - Subconjunctival hemorrhage
Sclera and cornea	Scleritis - Keratitis - Corneal ulcer - Snow blindness - Thygeson's superficial punctate keratopathy - Fuchs' dystrophy - Keratoconus - Keratoconjunctivitis sicca - Arc eye - Keratoconjunctivitis - Corneal neovascularization - Kayser-Fleischer ring - Arcus senilis
Iris and ciliary body	Iritis - Uveitis - Iridocyclitis - Hyphema - Persistent pupillary membrane
Lens	Cataract - Aphakia
Choroid and retina	Retinal detachment - Retinoschisis - Hypertensive retinopathy - Diabetic retinopathy - Retinopathy - Retinopathy of prematurity - Macular degeneration - Retinitis pigmentosa - Macular edema - Epiretinal membrane - Macular pucker
Ocular muscles, binocular movement, accommodation and refraction	Strabismus - Ophthalmoparesis - Progressive external ophthalmoplegia - Esotropia - Exotropia - Refractive error - Hyperopia - Myopia - Astigmatism - Anisometropia - Presbyopia - Fourth nerve palsy - Sixth nerve palsy - Kearns-Sayre syndrome - Esophoria - Exophoria - Duane syndrome - Convergence insufficiency - Internuclear ophthalmoplegia - Aniseikonia
Visual disturbances and blindness	Amblyopia - Leber's congenital amaurosis - Subjective (Asthenopia, Hemeralopia, Photophobia, Scintillating scotoma) - Diplopia - Scotoma - Anopsia (Binasal hemianopsia, Bitemporal hemianopsia, Homonymous hemianopsia, Quadrantanopia) - Color blindness (Achromatopsia) - Nyctalopia - Blindness/Low vision
Commonly associated infectious diseases	Trachoma - Onchocerciasis
Other	Glaucoma - Floater - Leber's hereditary optic neuropathy - Red eye - Argyll Robertson pupil - Keratomycosis - Xerophthalmia - Aniridia