Unreferenced date January 2010 Infobox disease Name Asthenopia ICD10 H53.1 ICD9 ICD9 368.13 Asthenopia aesthenopia or eye strain is an ophthalmology ophthalmological condition that manifests itself through nonspecific symptom s such as fatigue, pain in or around the eyes, blurred vision, headache and occasional diplopia double vision . Symptoms often occur after reading, computer work, or other close activities that involve tedious visual tasks. When concentrating on a visually intense task, such as continuously focusing on a book or computer monitor, the ciliary muscle tightens. This can cause the eyes to get irritated and uncomfortable. Giving the eyes a chance to focus on a distant object at least once an hour usually alleviates the problem. A Cathode ray tube CRT computer monitor with a low refresh rate 70 Hertz Hz or a CRT television can cause similar problems because the image has a visible flicker. Aging CRTs also often go slightly out of focus, and this can cause eye strain. Liquid crystal display LCDs do not go out of focus and are less susceptible to visible flicker. Causes Sometimes, asthenopia aesthenopia can be due to specific visual problems, such as uncorrected refraction error s or binocular vision problems like accommodative insufficiency or heterophoria . Quite frequently it s caused by looking at screens such as those of computers or phones. See also Computer vision syndrome Photophobia Eye examination Vision therapy Astigmatism Ophthalmic astigmatism Astigmatism External links wiktionary asthenopia http www.mayoclinic.com health eyestrain DS01084 Mayo Clinic entry on Eyestrain http www.eyesite.ca english public information eye facts reducing.htm Reducing Eye Strain Eye pathology Category Visual disturbances and blindness eye stub ar de Asthenopie hr Astenopija it Astenopia ja pl Astenopia pt Astenopia ru tl Astenopya ... more details
Holographic display is a display technology that has the ability to provide all four eye mechanism binocular disparity , motion parallax , Accommodation eye accommodation and Convergence eye convergence . The Three dimensional space 3D objects can be viewed without wearing any special glasses and no Asthenopia visual fatigue will be caused to human eyes. Electro holographic display Electro holographic display is a type of holographic display that uses electroholography for recording and reconstructing a 3D objects. This display has advantages over other 3D displays for example it can reconstruct 3D images with full parallax . See also Holography Holographic screen Computer generated holography Volumetric display Display technology Emerging technologies Category Display technology Category Holography Category 3D imaging Category Emerging technologies Tech stub el ... more details
Pseudomyopia refers to an intermittent and temporary shift in refraction of the eye towards myopia , in which the focusing of light in front of the retina is due to a transient spasm of the ciliary muscle causing an increase in the refractive power of the eye. It may be either organic, through stimulation of the parasympathetic nervous system , or functional in origin, through eye strain or fatigue of ocular systems. It is common in young adults who have active accommodation eye accommodation , and classically occurs after a change in visual requirements, such as students preparing for an exam, or a change in occupation. The major symptom is intermittent blurring of distance vision particularly noticeable after prolonged periods of near work, and symptoms of asthenopia . The vision may clear temporarily using concave minus lenses. The diagnosis is done by cycloplegia cycloplegic refraction using a strong cycloplegic like atropine or homatropine eye drops. Accommodative amplitude and facility may be reduced as a result of the ciliary muscle spasm. Treatment is dependent on the underlying aetiology. Organic causes may include systemic or ocular medications, brain stem injury, or active ocular inflammation such as uveitis . Functional pseudomyopia is managed though modification of working conditions, an updated refraction, or through appropriate ocular exercises. References Reflist cite journal author Chan R, Trobe J title Spasm of accommodation associated with closed head trauma. journal J Neuroophthalmol volume 22 issue 1 pages 15 7 year 2002 pmid 11937900 cite journal author Chentsova O, Shatalov O title Comparative analysis of the efficacy of some methods of conservative treatment of accommodation spasms and myopia in children journal Vestn Oftalmol volume 118 issue 6 pages 10 2 year 2002 pmid 12506647 See also Refraction Category Diseases of the eye and adnexa ... more details
Infobox disease Name Anisometropia ICD10 ICD10 H 52 3 h 49 ICD9 ICD9 367.31 Anisometropia IPAc en icon n a s m t r o p i USdict an &prime s m tr &prime p is the condition in which the two human eye eye s have unequal refractive power that is, are in different states of myopia nearsightedness , hyperopia farsightedness or in the extreme, antimetropia wherein one eye is myopic and the other is hyperopic , the unequal refractive states cause unequal rotations thus leading to diplopia and asthenopia . Anisometropia can adversely affect the development of binocular vision in infants and children if there is a large difference in clarity between the two eyes. The brain will often suppress the vision of the blurrier eye in a condition called amblyopia , or lazy eye. The name is from four Greek language Greek components an not, iso same, metr measure, ops eye. One study estimated that 6 of those between the ages of 6 and 18 have anisometropia. ref Czepita D, Goslawski W, Mojsa A. Occurrence of anisometropia among students ranging from 6 to 18 years of age. Klin Oczna. 2005 107 4 6 297 9. Polish. PMID 16118943. ref Spectacle correction For those with large degrees of anisometropia, spectacle correction may cause the person to experience a difference in image magnification between the two eyes which could also prevent the development of good binocular vision. The solution for spectacle wearers to the problem that spectacle correction may cause the person to experience a difference in image magnification between the two eyes is spectacles incorporating iseikonic lenses. Iseikonic lenses present adjusted image sizes to the eye compared to standard lenses. The formula for iseikonic lenses without cylinder is Magnification 1 1 t n P X 1 1 hF where t center thickness in meters n refractive index P front base curve h vertex distance in meters F back vertex power essentially, the prescription for the lens see Practical Optical Dispensing by David Wilson If the di ... more details
Infobox Disease Name Convergence Insufficency Image Caption DiseasesDB ICD10 ICD10 H 51 1 h 49 ICD9 ICD9 378.83 ICDO OMIM MedlinePlus eMedicineSubj oph eMedicineTopic 553 MeshID D015835 Convergence insufficiency or Convergence Disorder is a sensory and neuromuscular anomaly of the binocular vision system, characterized by an inability of the Human eyes eyes to turn towards each other, or sustain Convergence eye convergence . Symptoms The symptoms and signs associated with convergence insufficiency are related to prolonged, visually demanding, near centered tasks. They may include, but are not limited to, diplopia double vision , asthenopia eye strain , transient blurred vision, difficulty sustaining near visual function, abnormal fatigue, headache , and abnormal postural adaptation, among others. Note that some Internet resources confuse convergence and divergence dysfunction, reversing them. Diagnosis Diagnosis of convergence insufficiency is made by an eye care professional skilled in binocular vision dysfunctions to rule out any organic disease. Convergence insufficiency characterized by one or more of the following diagnostic findings High exophoria at near, reduced accommodative convergence accommodation eye accommodation ratio, receded near point of convergence , low fusional vergence ranges and or facility. Treatment Convergence insufficiency may be treated with convergence exercises prescribed by an eyecare specialist trained in vision therapy, orthoptics, and binocular vision anomalies. Some cases of convergence insufficiency are successfully managed by prescription of eyeglasses with therapeutic Prism optics prisms and or lens optics lenses in addition to the therapy regime. In 2005, the Convergence Insufficiency Treatment Trial CITT published two randomized clinical studies. The first, published in Archives of Ophthalmology demonstrated that computer exercises when combined with in office based vision therapy was more effective than pencil pushups or comp ... more details
Infobox disease Name Hypermetropia ICD10 ICD10 H 52 0 h 49 ICD9 ICD9 367.0 Hyperopia , also known as farsightedness , longsightedness or hypermetropia , is a wikt defect defect of visual system vision caused by an imperfection in the Human eye eye often when the eyeball is too short or the Lens anatomy lens cannot become round enough , causing difficulty focusing on near objects, and in extreme cases causing a sufferer to be unable to focus on objects at any distance . As an object moves toward the eye, the eye must increase its optical power to keep the image in focus on the retina. If the power of the cornea and lens is insufficient, as in hyperopia, the image will appear blurred. Image Hypermetropia.svg thumb 250 px right Hyperopia, and restoring of vision with convex lens. People with hyperopia can experience defocus aberration blurred vision , asthenopia , accommodation eye Accommodative dysfunction accommodative dysfunction , binocular vision binocular dysfunction , amblyopia , and strabismus . ref name AOA Hyperopia American Optometric Association. http www.aoa.org documents CPG 16.pdf Optometric Clinical Practice Guideline Care of the patient with hyperopia. 1997. ref Hyperopia is often confused with presbyopia , ref name WebMD http www.webmd.com content article 63 72009 Eye Health Presbyopia and Your Eyes. WebMD.com. October, 2005. Accessed September 21, 2006. ref ref Chou B. http www.refractivesource.com patients ref error pres.htm Refractive Error and Presbyopia. Refractive Source.com Accessed September 20, 2006. ref another condition that frequently causes blurry near vision. ref name AOA Presbyopia American Optometric Association. http www.aoa.org documents CPG 17.pdf Optometric Clinical Practice Guideline Care of the patient with presbyopia. 1998. ref Presbyopes who report good far vision typically experience blurry near vision because of a reduced accommodative amplitude brought about by natural aging changes with the crystalline lens . ref name AOA P ... more details
skills required for reading process reading , asthenopia eye strain , visually induced headaches ... insufficiency is a common binocular vision disorder characterized by asthenopia , eye fatigue and discomfort ... Retrieved August 2, 2006. ref Asthenopia may be aggravated by close work and is thought by some ... of asthenopia and the convergence eye convergence ability of the eyes. ref cite journal last1 Scheiman ... more details
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