WordNet

mark with diacritics; "point the letter"
a very small circular shape; "a row of points"; "draw lines between the dots" (同)dot
an instant of time; "at that point I had to leave" (同)point in time
repair the joints of bricks; "point a chimney" (同)repoint
a V shape; "the cannibals teeth were filed to sharp points" (同)tip, peak
a linear unit used to measure the size of type; approximately 1/72 inch
a style in speech or writing that arrests attention and has a penetrating or convincing quality or effect
one percent of the total principal of a loan; it is paid at the time the loan is made and is independent of the interest on the loan
the unit of counting in scoring a game or contest; "he scored 20 points in the first half"; "a touchdown counts 6 points"
the gun muzzles direction; "he held me up at the point of a gun" (同)gunpoint
the property of a shape that tapers to a sharp tip (同)pointedness
a wall socket (同)power_point
an outstanding characteristic; "his acting was one of the high points of the movie" (同)spot
a distinguishing or individuating characteristic; "he knows my bad points as well as my good points"
sharp end; "he stuck the point of the knife into a tree"; "he broke the point of his pencil"
a V-shaped mark at one end of an arrow pointer; "the point of the arrow was due north" (同)head
a brief version of the essential meaning of something; "get to the point"; "he missed the point of the joke"; "life has lost its point"
a geometric element that has position but no extension; "a point is defined by its coordinates"
a promontory extending out into a large body of water; "they sailed south around the point"
the object of an activity; "what is the point of discussing it?"
the precise location of something; a spatially limited location; "she walked to a point where she could survey the whole street"
be positionable in a specified manner; "The gun points with ease"
indicate the presence of (game) by standing and pointing with the muzzle; "the dog pointed the dead duck"
mark (a psalm text) to indicate the points at which the music changes
mark (Hebrew words) with diacritics
closely resembling the genuine article; "near beer"; "a dress of near satin"
not far distant in time or space or degree or circumstances; "near neighbors"; "in the near future"; "they are near equals"; "his nearest approach to success"; "a very near thing"; "a near hit by the bomb"; "she was near tears"; "she was close to tears"; "had a close call" (同)close, nigh
being on the left side; "the near or nigh horse is the one on the left"; "the animals left side is its near or nigh side" (同)nigh
near in time or place or relationship; "as the wedding day drew near"; "stood near the door"; "dont shoot until they come near"; "getting near to the true explanation"; "her mother is always near"; "The end draws nigh"; "the bullet didnt come close"; "dont get too close to the fire" (同)nigh, close
having a point
direct and obvious in meaning or reference; often unpleasant; "a pointed critique"; "a pointed allusion to what was going on"; "another pointed look in their direction"
Hawaiian dish of taro root pounded to a paste and often allowed to ferment

PrepTutorEJDIC

〈C〉(針・鉛筆・剣などの)『とがった先』,(…の)先端《+『of』+『名』》 / 〈C〉岬(みさき) / 〈C〉(小数点・句読点などの)点 / 〈C〉(図形上の)点 / 〈C〉(ある特定の)『地点』(spot),場所(place) / 〈C〉(計器の目盛りなどの)『点』,『度』 / 〈C〉時点,瞬間 / 〈C〉《単数形で》(物語・議論などの)『要点』,核心《+『of』(『in』)+『名』》 / 〈U〉(…の)『目的』,『意義』,ねらっている点《+『of』(『in』)+『名』(do『ing』)》 / 〈C〉(全体の中の)個々の項目,細目(item),細部(detail) / 〈C〉特徴(characteristic),特質(trait) / 〈C〉(競技・学校の成績などの)得点 / 〈C〉ポイント(活字の大きさの単位;約1/72インチの大きさ) / (…に)〈銃・指など〉‘を'『向ける』《+『名』+『at』(『to, toward』)+『名』》 / …‘に'『指し示す』《point+名+to+名…に…をさし示す》 / …‘の'先をとがらせる,‘に'先を付ける / …‘に'点を打つ;…‘に'小数点を付ける;…‘に'句読点を付ける / 〈猟犬が〉〈獲物〉‘を'指し示す / (…を)(指などで)『示す』,指し示す《+『at』(『to, toward』)+『名』(do『ing』)》 / 〈猟犬が〉獲物の位置を示す
(空間的・時間的に)(…の)『近くに』,(…に)接近して《+『to』+『名』》 / 《しばしば複合語を作って》『ほとんど』(almost, nearly) / (空間的・時間的に)『近い』,接近した / (関係などが)『身近な』 / 『きわどい』,やっとの / (空間的・時間的に)…『に近く』,『の近くに』 / (状態などが)…に近く,…しそうで / (時間・空間上)…‘に'近づく / 近づく,接近する
「ほとんど…,ほぼ…」の意を表す
『先のとがった』,鋭い / (皮肉など)痛烈な,しんらつな / (ある目標に)向けられた,(はっきりと特定の人に)向けられた,当てこすりの

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/04/29 06:16:20」(JST)

wiki en

Presbyopia is a condition where, with age, the eye exhibits a progressively diminished ability to focus on near objects. Presbyopia’s exact mechanisms are not known with certainty; the research evidence most strongly supports a loss of elasticity of the crystalline lens, although changes in the lens’ 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. Like gray hair and wrinkles, presbyopia is a symptom caused by the natural course of aging. The first signs of presbyopia – eyestrain, difficulty seeing in dim light, problems focusing on small objects and/or fine print – are usually first noticed between the ages of 40 and 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 age 25 (100 mm), and levels off at 0.5 to 1 dioptre at age 60 (ability to focus down to 1–2 meters only). The expected, maximum, and minimum amplitudes of accommodation in diopters (D) for a corrected patient of a given age can be estimated using Hofstetter's formulas: Expected amplitude (D) = 18.5 - 0.3 x (age in years), Maximum amplitude (D) = 25 - 0.4 x (age in years), Minimum amplitude (D) = 15 - 0.25 x (age in years).^[1]

The word presbyopia comes from the Greek word presbys (πρέσβυς), meaning "old man" or "elder", and the ancient Greek word ops (ὤψ), meaning "eye".^[2]

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 extreme presbyopes complain that their arms have become "too short" to hold reading material at a comfortable distance.^[3]

Presbyopia symptoms, like other focus defects, become much less noticeable in bright sunlight due to the action of the iris closing to a smaller diameter.^[4] As with any lens, increasing the focal ratio of the lens increases depth of field by reducing the level of blur of out-of-focus objects (compare the effect of aperture on depth of field in photography).

A delayed onset of seeking correction for presbyopia has been found among those with certain professions and those with miotic pupils.^[5] In particular, farmers and homemakers seek correction later, whereas service workers and construction workers seek eyesight correction earlier. Scuba divers with interest in underwater photography may notice presbyopic changes while diving before they recognize the symptoms in their normal routines due to the near focus in low light conditions.^[6]

Focusing mechanism of the eye

Main article: Accommodation (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.

Without correction, the near point is at 3 inches (7 cm) at age 10, to 6 inches (16 cm) at age 40, to 39 inches (1 meter) at age 60. As a result, a 60-year-old must use corrective lenses to read books or magazines at a comfortable distance.^[7]

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,^[8] 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 become more round, for close vision. This implies 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 farther 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 to focus at close range.^{[citation needed]} This has the counter-intuitive effect of steepening the lens valve cytokinesis centrally (increasing its power) and flattening peripherally.

Interaction with myopia

Many people with myopia (near-sightedness) can read comfortably without eyeglasses or contact lenses even after age 40. However, their myopia does not disappear and the long-distance visual challenges remain. Myopes considering refractive surgery are advised that surgically correcting their nearsightedness may be a disadvantage after age 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. Myopes with astigmatism find near vision better, though not perfect, without glasses or contact lenses when presbyopia sets in, but the more astigmatism, the poorer their uncorrected near vision.

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. Monovision can be created with contact lenses, so candidates for this procedure can determine if they are prepared to have their corneas reshaped by surgery to cause this effect permanently.

Monovision does not work well for spectacles, since the user will not always look through the optical centres of the lenses, causing double images. That problem is not present with contacts or laser surgery.^[9]

Treatment

In the visual system, images captured by the eye are translated into electric signals that are transmitted to the brain where they are interpreted. As such, in order to overcome presbyopia, two main components of the visual system can be addressed: 1) the optical system of the eye or 2) the visual processing of the brain.

Image capturing in the eye - Solutions for presbyopia have advanced significantly in recent years, thanks to widened availability of optometry care as well as over-the-counter vision correction.
Image processing in the brain - Scientific solutions for overcoming the symptoms of presbyopia were developed in recent years and tested successfully in multiple studies. These solutions are available thanks to significant progress in the understanding of the human brain plasticity and the field of perceptual learning.^[10]

Corrective lenses

Corrective lenses provide a range of vision correction, some as high as +4.0 diopter. Some with presbyopia choose varifocal or bifocal lenses to eliminate the need for a separate pair of reading glasses; specialized preparations of varifocals or bifocals usually require the services of an optometrist. Some newer bifocal or varifocal spectacle lenses attempt to correct both near and far vision with the same lens.^[11]

Contact lenses can also be used to correct the focusing loss that comes along with presbyopia. Some people choose contact lenses to correct one eye for near and one eye for far with a method called monovision, which can interfere with depth perception due to loss of focusing ability in the other eye.

Exercises

Available treatment programs based upon exercising the ciliary muscles have not proven effective.^[12]

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. INTRACOR^[13] has now been approved in Europe for treatment of both eyes (turning both corneas into multifocal lenses and so dispensing with the need for reading glasses).

Surgical treatments that reshape the cornea, such as PresbyLASIK and conductive keratoplasty, are also worth consideration, but some use of reading glasses will still remain when light is poor or when reading for extended periods of time, since such procedures do nothing for crystalline lens deterioration.^[14]

Surgical procedures for the correction of presbyopia without reshaping the cornea, using scleral band expansion (SBE) were proposed by Scharcker, M.D.and J.T. Lin, Ph.D., using a laser scleral ablation in US Pat # 6,258,082 (2001). These procedures are different from PresbyLasik, and claim to create the true increase of accommodation of the eye by increasing the space between the ciliary body and lens. SBEs have not been found to provide predictable or consistent results in the treatment of presbyopia.^[15]

Another treatment option for the correction of presbyopia in patients with emmetropia, as well as in patients with myopia, hyperopia and astigmatism is laser blended vision. This procedure uses laser refractive surgery to correct the dominant eye mainly for distance vision and the nondominant eye mainly for near vision, while the depth of field (i.e. the range of distances at which the image is in focus) of each eye is increased. As a result of the increased depth of field, the brain merges the two images, creating a blend zone, i.e. a zone which is in focus for both eyes. This allows the patient to see near, intermediate and far without glasses. Some literature also suggests the benefits achieved include the brain learning to adapt, assimilating two images, one of which is out of focus. Over time, many patients report they are unaware one eye is out of focus.^[16]^[17]^[18]

IsoVision: developed since 2008 by Dr. Frederic HEHN, laser surgery used to correct all refractive errors (myopia, hyperopia, astigmatism) associated with presbyopia. The treatment consists of two phases: one for distance vision and one for near vision. This allows an efficient, sustainable and safe treatment in time.^[19]

Surgically implanted corneal inlays are another treatment option for presbyopia. Corneal inlays typically are implanted in the nondominant eye to minimize impact to binocular uncorrected distance vision.^[20] They seek to improve near vision in one of three ways: The Flexivue Microlens (Presbia) changes the central refractive index, the Kamra (AcuFocus) increases the depth of focus through the use of a pinhole, and the Vue+ (Revision Optics) reshapes the central cornea.^[21]

Brain image processing enhancement

Scientists' understanding of the ability of the adult brain to change, termed neuroplasticity, has been vastly advanced during the last 20 years, giving rise to solutions based on perceptual learning. Perceptual learning, standing for repeated practice on a demanding task, improves visual skills by enhancing the image processing in the brain. Several great achievements in this field include FDA-approved solutions for severe visual problems such as amblyopia, loss of vision resulting from a stroke, and others. Academic research on perceptual learning has been published in leading academic journals, including Nature, Science, PNAS, Vision Research and others,^[22]^[23] including studies showing improved visual performance in presbyopes.^[10]^[24]^[25] Improvements in visual functions following perceptual learning are achieved without changing the optical characteristics of the presbyopic eye, implying enough retained plasticity in the aging brain to offset the natural biological deterioration of the eyes. Thus, the unavoidable deterioration of the eyes with age can be compensated by boosting the speed and quality of image processing in the visual cortex of the brain.^[26]

References

^ Robert P. Rutstein, Kent M. Daum, Anomalies of Binocular Vision: Diagnosis & Management, Mosby, 1998.
^ http://dictionary.reference.com/browse/presbyopia. Missing or empty |title= (help)
^ Robert Abel, The Eye Care Revolution: Prevent and Reverse Common Vision Problems, Kensington Books, 2004.
^ "Presbyopia: Patient Information". Marquette, Michigan, USA: Eye Associates of Marquette. 2008. Retrieved 2010-10-31.
^ García Serrano, JL; López Raya, R; Mylonopoulos Caripidis, T (Nov 2002). "Variables related to the first presbyopia correction" (Free full text). Archivos de la Sociedad Espanola de Oftalmologia 77 (11): 597–604. ISSN 0365-6691. PMID 12410405.
^ Bennett QM (June 2008). "New thoughts on the correction of presbyopia for divers". Diving Hyperb Med 38 (2): 163–4. PMID 22692711. Retrieved 2013-04-19.
^ "Sensory Reception Human Vision Structure and Function of the Eye" Encyolpaedia Britannica 1987
^ Gregory, Richard Langton (1977). Eye and brain : the psychology of seeing. (3rd ed. rev. and update. ed.). New York ; Toronto: McGraw-Hill. ISBN 0070246653.
^ Specsavers: Monovision in glasses, On 25 April 2013 by Simon Kay
^ ^a ^b Polat, U., Schor, C., Tong, J., Zomet, A., Lev, M., Yehezkel, O., Sterkin, A., & Levi, D.M. (2012). Training the brain to overcome the effect of aging on the human eye. Scientific Reports 2, Article number: 278. doi:10.1038/srep00278
^ Li, G; Mathine, DL; Valley, P; Ayräs, P; Haddock, JN; Giridhar, MS; Williby, G; Schwiegerling, J et al. (Apr 2006). "Switchable electro-optic diffractive lens with high efficiency for ophthalmic applications" (Free full text). Proceedings of the National Academy of Sciences of the United States of America 103 (16): 6100–4. doi:10.1073/pnas.0600850103. ISSN 0027-8424. PMC 1458838. PMID 16597675.
^ The lowdown on eye exercises, Harvard Medical School Family Health Guide http://www.health.harvard.edu/fhg/updates/update0903c.shtml
^ http://www.technolaspv.com
^ "LASIK and Presbyopia". Medical Management Services Group, The. Retrieved 2010-10-31.
^ Malecaze, FJ; Gazagne, CS; Tarroux, MC; Gorrand, JM (Dec 2001). "Scleral expansion bands for presbyopia". Ophthalmology 108 (12): 2165–71. doi:10.1016/S0161-6420(01)00591-7. ISSN 0161-6420. PMID 11733253.
^ Reinstein DZ, Couch DG, Archer TJ. LASIK for Hyperopic Astigmatism and Presbyopia Using Micro-monovision With the Carl Zeiss Meditec MEL80. J Refract Surg. 2009;25:37-58
^ Reinstein DZ, Archer TJ, Gobbe M. LASIK for the correction of myopic astigmatism and presbyopia using aspheric ablation profiles and a micro-monovision protocol with the Carl Zeiss Meditec MEL80. J Refract Surg. [In Press]
^ Reinstein DZ, Archer TJ, Gobbe M. Outcomes of Presbyopic Micro-Monovision LASIK for Myopia, Hyperopia and Emmetropia. ESCRS. Berlin, 2008
^ Advanced Isovision: Predictable PresbyLASIK > Femtosecond Laser: Techniques and Technology. JP Medical Ltd. 2012.
^ Chang, Clark. "Novel Approaches to Treating Presbyopia" Review of Cornea & Contact Lenses. September 2011
^ Dalton, Michelle. "Intracorneal Inlays Showing Positive Outcomes" EyeWorld. June 2011
^ Sagi, D. (2011). Perceptual learning in Vision Research. Vision Res, 51(13):1552-66.
^ Fahle, M., & Poggio, T. (2002). Perceptual learning. Cambridge, Massachusetts: MIT Press.
^ Polat, U. (2009). Making perceptual learning practical to improve visual functions. Vision Res, 49 (21), 2566-73.
^ Polat, U. (2009). Perceptual learning induces neuroplasticity, enabling improvement of visual functions. Expert Review of Ophthalmology, 4 (6), 573-576.
^ Uri Polat; Clifton Schor, Jiang-Liang Tong, Ativ Zomet, Maria Lev, Oren Yehezkel, Anna Sterkin, & Dennis M. Levi. "Training the brain to overcome the effect of aging on the human eye". Nature. Retrieved 22 July 2012. Cite uses deprecated parameters (help)

External links

Look up presbyopia in Wiktionary, the free dictionary.

Educational Video About Presbyopia
Vision Over 40
Presbyopia at MedLinePlus Medical Encyclopedia
*Ray Gottlieb, O.D., Ph.D. "Presbyopia Reduction" (PDF). —Chart with exercise proposed to reverse presbyopia.

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English Journal

Chronic fluoxetine exposure alters movement and burrowing in adult freshwater mussels.

Hazelton PD1, Du B2, Haddad SP3, Fritts AK4, Chambliss CK5, Brooks BW2, Bringolf RB6.Author information 1Interdisciplinary Toxicology Program, University of Georgia, Athens, GA, United States; Warnell School of Forestry & Natural Resources, University of Georgia, Athens, GA, United States. Electronic address: peter.hazelton@state.ma.us.2The Institute of Ecological, Earth and Environmental Sciences, Baylor University, Waco, TX, United States.3Department of Environmental Science, Center for Reservoir and Aquatic Systems Research, Baylor University, Waco, TX, United States.4Warnell School of Forestry & Natural Resources, University of Georgia, Athens, GA, United States.5The Institute of Ecological, Earth and Environmental Sciences, Baylor University, Waco, TX, United States; Department of Environmental Science, Center for Reservoir and Aquatic Systems Research, Baylor University, Waco, TX, United States; Department of Chemistry and Biochemistry, Baylor University, Waco, TX, United States.6Interdisciplinary Toxicology Program, University of Georgia, Athens, GA, United States; Warnell School of Forestry & Natural Resources, University of Georgia, Athens, GA, United States. Electronic address: bringo@uga.edu.AbstractThe antidepressant fluoxetine is commonly found in aquatic fauna living near or downstream from point-sources of municipal waste effluent. Continuous release of fluoxetine results in increased effective exposure duration in surface waters, resulting in a chronic exposure for animals downstream, particularly in effluent dominated ecosystems. Fluoxetine is known to cause disruptions in reproductive behavior of freshwater mussels (order Unionoida), including stimulating release of gametes, parturition of glochidia (larvae), and changes in lure display and foot protrusion. However, the ecological relevance of these effects at environmental concentrations is unknown. We conducted a 67-d exposure of adult Lampsilis fasciola to fluoxetine concentrations of 0, 0.5, 2.5, and 22.3μg/L and assessed impacts on behavior (lateral movement, burrowing, and filtering) and metabolism (glycogen storage and respiration). Mussels treated with 2.5 and 22.3μg/L fluoxetine displayed mantle lures significantly (p<0.05) more than controls. Animals treated with 22.3μg/L fluoxetine were statistically more likely to have shorter time-to-movement, greater total movement, and initiate burrowing sooner than control animals. These observations suggest that increased activity of mussels exposed to fluoxetine may result in increased susceptibility to predators and may lead to a reduction in energy stores.
Aquatic toxicology (Amsterdam, Netherlands).Aquat Toxicol.2014 Jun;151:27-35. doi: 10.1016/j.aquatox.2013.12.019. Epub 2013 Dec 28.
The antidepressant fluoxetine is commonly found in aquatic fauna living near or downstream from point-sources of municipal waste effluent. Continuous release of fluoxetine results in increased effective exposure duration in surface waters, resulting in a chronic exposure for animals downstream, part
PMID 24438840

Upper extremity hemodynamics and sensation with backpack loads.

Kim SH1, Neuschwander TB2, Macias BR3, Bachman L Jr4, Hargens AR5.Author information 1Department of Orthopaedic Surgery, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Republic of Korea. Electronic address: drjacobkim@gmail.com.2Department of Orthopaedic Surgery, University of California, UCSD Medical Center, San Diego, USA. Electronic address: tneuschwander@ucsd.edu.3Department of Health & Kinesiology, Texas A&M University, USA. Electronic address: dr.brandonmacias@gmail.com.4Department of Orthopaedic Surgery, University of California, UCSD Medical Center, San Diego, USA. Electronic address: jr@ucsd.edu.5Department of Orthopaedic Surgery, University of California, UCSD Medical Center, San Diego, USA. Electronic address: ahargens@ucsd.edu.AbstractHeavy backpacks are often used in extreme environments, for example by military during combat, therefore completion of tasks quickly and efficiently is of operational relevance. The purpose of this study was to quantify hemodynamic parameters (brachial artery Doppler and microvascular flow by photoplethysmography; tissue oxygenation by near-infrared spectroscopy; arterial oxygen saturation by pulse oximeter) and sensation in upper extremities and hands (Semmes-Weinstein monofilament test and 2-point discrimination test) while wearing a loaded backpack (12 kg) in healthy adults for 10 min. All values were compared to baseline before wearing a backpack. Moderate weight loaded backpack loads significantly decreased upper extremity sensation as well as all macrovascular and microvascular hemodynamic values. Decreased macrovascular and microvascular hemodynamics may produce neurological dysfunction and consequently, probably affect fine motor control of the hands.
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PMID 24075289