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Far-sightedness, also known as long-sightedness, hypermetropia, or hyperopia, is a condition of the
eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...
where distant objects are seen clearly but near objects appear blurred. This blurred effect is due to incoming light being focused behind, instead of on, the
retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...
wall due to insufficient accommodation by the lens. Minor hypermetropia in young patients is usually corrected by their accommodation, without any defects in vision. But, due to this accommodative effort for distant vision, people may complain of
eye strain Eye strain, also known as asthenopia (from Greek ''a-sthen-opia'', grc, ἀσθενωπία, ), is a common eye condition that manifests through non-specific symptoms such as fatigue, pain in or around the eyes, blurred vision, headache, and ...
during prolonged reading. Some hypermetropes can see clear at distance, but near vision may be blurred due to insufficient accommodation. For this reason, this defect is referred as far-sightedness. If the hypermetropia is high, there will be defective vision for both distance and near. People may also experience accommodative dysfunction, binocular dysfunction,
amblyopia Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to fully process input from one eye and over time favors the other eye. It results in decreased vision in an eye that typically appears normal in other aspects. Amb ...
, and
strabismus Strabismus is a vision disorder in which the eyes do not properly align with each other when looking at an object. The eye that is focused on an object can alternate. The condition may be present occasionally or constantly. If present during a ...
. Newborns are almost invariably hypermetropic, but it gradually decreases as the newborn gets older. There are many causes for this condition. It may occur when the axial length of eyeball is too short or if the
lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...
or
cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power ...
is flatter than normal. Changes in refractive index of lens, alterations in position of the lens or absence of lens are the other main causes. Risk factors include a family history of the condition,
diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
, certain medications, and
tumors A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
around the eye. It is a type of
refractive error Refractive error, also known as refraction error, is a problem with focus (optics), focusing light accurately on the retina due to the shape of the human eye, eye and or cornea. The most common types of refractive error are myopia, near-sightedne ...
. Diagnosis is based on an
eye exam An eye examination is a series of tests performed to assess vision and ability to focus on and discern objects. It also includes other tests and examinations pertaining to the eyes. Eye examinations are primarily performed by an optometrist, oph ...
. Management can occur with
eyeglasses Glasses, also known as eyeglasses or spectacles, are vision eyewear, with lenses (clear or tinted) mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms (known as temples or ...
,
contact lenses Contact lenses, or simply contacts, are thin lenses placed directly on the surface of the eyes. Contact lenses are ocular prosthetic devices used by over 150 million people worldwide, and they can be worn to correct vision or for cosmetic ...
, or refractive corneal surgeries. Glasses are easiest while contact lenses can provide a wider
field of vision The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments". Or simply, visual field can be defined as the entire area that can be seen when an eye is fixed straight at a point ...
. Surgery works by changing the shape of the cornea. Far-sightedness primarily affects young children, with rates of 8% at 6 years and 1% at 15 years. It then becomes more common again after the age of 40, known as
presbyopia Presbyopia is physiological insufficiency of accommodation associated with the aging of the eye that results in progressively worsening ability to focus clearly on close objects. Also known as age-related farsightedness (or age-related long si ...
, affecting about half of people. Best treatment option to correct hypermetropia due to
aphakia Aphakia is the absence of the lens of the eye, due to surgical removal, such as in cataract surgery, a perforating wound or ulcer, or congenital anomaly. It causes a loss of accommodation, high degree of farsightedness (hyperopia), and a deep a ...
is
IOL Cherchell (Arabic: شرشال) is a town on Algeria's Mediterranean coast, west of Algiers. It is the seat of Cherchell District in Tipaza Province. Under the names Iol and Caesarea, it was formerly a Roman colony and the capital of the kin ...
implantation. Other common types of refractive errors are
near-sightedness Near-sightedness, also known as myopia and short-sightedness, is an eye disease where light focuses in front of, instead of on, the retina. As a result, distant objects appear blurry while close objects appear normal. Other symptoms may include ...
,
astigmatism Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at nig ...
, and
presbyopia Presbyopia is physiological insufficiency of accommodation associated with the aging of the eye that results in progressively worsening ability to focus clearly on close objects. Also known as age-related farsightedness (or age-related long si ...
.


Signs and symptoms

In young patients, mild hypermetropia may not produce any symptoms. The signs and symptoms of far-sightedness include
blurry vision Blurred vision is an ocular symptom where vision becomes less precise and there is added difficulty to resolve fine details. Temporary blurred vision may involve dry eyes, eye infections, alcohol poisoning, hypoglycemia, or low blood pressure. ...
, frontal or fronto temporal
headaches Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result of m ...
,
eye strain Eye strain, also known as asthenopia (from Greek ''a-sthen-opia'', grc, ἀσθενωπία, ), is a common eye condition that manifests through non-specific symptoms such as fatigue, pain in or around the eyes, blurred vision, headache, and ...
, tiredness of eyes etc. The common symptom is eye strain. Difficulty seeing with both eyes (
binocular vision In biology, binocular vision is a type of vision in which an animal has two eyes capable of facing the same direction to perceive a single three-dimensional image of its surroundings. Binocular vision does not typically refer to vision where an ...
) may occur, as well as difficulty with depth perception. The asthenopic symptoms and near blur are usually seen after close work, especially in the evening or night.


Complications

Far-sightedness can have rare complications such as
strabismus Strabismus is a vision disorder in which the eyes do not properly align with each other when looking at an object. The eye that is focused on an object can alternate. The condition may be present occasionally or constantly. If present during a ...
and
amblyopia Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to fully process input from one eye and over time favors the other eye. It results in decreased vision in an eye that typically appears normal in other aspects. Amb ...
. At a young age, severe far-sightedness can cause the child to have double vision as a result of "over-focusing". Hypermetropic patients with short axial length are at higher risk of developing primary angle closure glaucoma, so, routine
gonioscopy Gonioscopy a routine ophthalmological procedure that measures the angle between the iris and the cornea (the iridocorneal angle), using a goniolens (also known as a gonioscope) together with a slit lamp or operating microscope. Its use is import ...
and glaucoma evaluation is recommended for all hypermetropic adults.


Causes

Simple hypermetropia, the most common form of hypermetropia, is caused by normal biological variations in the development of eyeball. Aetiologically, causes of hypermetropia can be classified as: * Axial: Axial hypermetropia occur when the axial length of eyeball is too short. About 1 mm decrease in axial length cause 3 diopters of hypermetropia. One condition that cause axial hypermetropia is nanophthalmos. * Curvatural: Curvatural hypermetropia occur when curvature of lens or cornea is flatter than normal. About 1 mm increase in
radius of curvature In differential geometry, the radius of curvature, , is the reciprocal of the curvature. For a curve, it equals the radius of the circular arc which best approximates the curve at that point. For surfaces, the radius of curvature is the radius o ...
results in 6 diopters of hypermetropia. Cornea is flatter in microcornea and cornea plana. * Index: Age related changes in refractive index (cortical sclerosis) can cause hypermetropia. Another cause of index hypermetropia is diabetes. Occasionally, mild hypermetropic shift may be seen in association with cortical or subcapsular cataract also. * Positional: Positional hypermetropia occur due to posterior dislocation of Lens or IOL. It may occur due to trauma. * Consecutive: Consecutive hypermetropia occur due to surgical over correction of myopia or surgical under correction in cataract surgery. * Functional: Functional hypermetropia results from paralysis of accommodation as seen in internal ophthalmoplegia, CN III palsy etc. * Absence of lens: Congenital or acquired aphakia cause high degree hypermetropia. Far-sightedness is often present from birth, but children have a very flexible eye lens, which helps to compensate. In rare instances hyperopia can be due to
diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
, and problems with the
blood vessels The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away f ...
in the
retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...
.


Diagnosis

A diagnosis of far-sightedness is made by utilizing either a retinoscope or an automated refractor-objective refraction; or trial lenses in a trial frame or a phoropter to obtain a subjective examination. Ancillary tests for abnormal structures and physiology can be made via a
slit lamp A slit lamp is an instrument consisting of a high-intensity light source that can be focused to shine a thin sheet of light into the eye. It is used in conjunction with a biomicroscope. The lamp facilitates an examination of the anterior segm ...
test, which examines the cornea,
conjunctiva The conjunctiva is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epithelium ...
, anterior chamber, and
iris Iris most often refers to: *Iris (anatomy), part of the eye *Iris (mythology), a Greek goddess * ''Iris'' (plant), a genus of flowering plants *Iris (color), an ambiguous color term Iris or IRIS may also refer to: Arts and media Fictional enti ...
. In severe cases of hyperopia from birth, the brain has difficulty in merging the images that each individual eye sees. This is because the images the brain receives from each eye are always blurred. A child with severe hyperopia can never see objects in detail. If the brain never learns to see objects in detail, then there is a high chance of one eye becoming dominant. The result is that the brain will block the impulses of the non-dominant eye. In contrast, the child with
myopia Near-sightedness, also known as myopia and short-sightedness, is an eye disease where light focuses in front of, instead of on, the retina. As a result, distant objects appear blurry while close objects appear normal. Other symptoms may include ...
can see objects close to the eye in detail and does learn at an early age to see objects in detail.


Classification

Hyperopia is typically classified according to clinical appearance, its severity, or how it relates to the eye's accommodative status.


Clinical classification

There are three clinical categories of hyperopia. * Simple hyperopia: Occurs naturally due to biological diversity. * Pathological hyperopia: Caused by disease, trauma, or abnormal development. * Functional hyperopia: Caused by paralysis that interferes eye's ability to accommodate.


Classification according to severity

There are also three categories severity: * Low:
Refractive error Refractive error, also known as refraction error, is a problem with focus (optics), focusing light accurately on the retina due to the shape of the human eye, eye and or cornea. The most common types of refractive error are myopia, near-sightedne ...
less than or equal to +2.00
diopters A dioptre (British spelling) or diopter (American spelling) is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, 1 dioptre = 1 m−1. It is normally used to express the optical power of a lens or curv ...
(D). * Moderate: Refractive error greater than +2.00 D up to +5.00 D. * High: Refractive error greater than +5.00 D.


Components of hypermetropia

Accommodation has significant role in hyperopia. Considering accommodative status, hyperopia can be classified as: * Total hypermetropia: It is the total amount of hyperopia which is obtained after complete relaxation of accommodation using cycloplegics like
atropine Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given i ...
. * Latent hyperopia: It is the amount of hyperopia normally corrected by ciliary tone (approximately 1 diopter). * Manifest hyperopia: It is the amount of hyperopia not corrected by ciliary tone. Manifest hyperopia is further classified into two, facultative and absolute. ** Facultative hyperopia: It is the part of hyperopia corrected by patient's accommodation. ** Absolute hyperopia: It is the residual part of hyperopia which causes blurring of vision for distance. So, Total hyperopia= latent hyperopia + manifest hyperopia (facultative + absolute)


Treatment


Corrective lenses

The simplest form of treatment for far-sightedness is the use of
corrective lens A corrective lens is a lens (i.e. a transmissive optical device) that is typically worn in front of the eye to improve daily vision. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glass ...
es, i.e. eyeglasses or contact lenses. Eyeglasses used to correct far-sightedness have
convex lens A lens is a transmissive optics, optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a #Compound lenses, compound lens consists of several simp ...
es.


Surgery

There are also surgical treatments for far-sightedness: Laser procedures *
Photorefractive keratectomy Photorefractive keratectomy (PRK) and laser-assisted sub-epithelial keratectomy (or laser epithelial keratomileusis) (LASEK) are laser eye surgery procedures intended to correct a person's vision, reducing dependency on glasses or contact lenses. ...
(PRK): This is a refractive technique that is done by removal of a minimal amount of the corneal surface. Hyperopic PRK has many complications like regression effect, astigmatism due to epithelial healing, and corneal haze. Post operative epithelial healing time is also more for PRK. * Laser assisted in situ keratomileusis (LASIK): Laser eye surgery to reshape the cornea, so that glasses or contact lenses are no longer needed. Excimer laser LASIK can correct hypermetropia up to +6 diopters. LASIK is contraindicated in patients with
lupus Lupus, technically known as systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Comm ...
and
rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are involv ...
. * Laser epithelial keratomileusis (LASEK): Resembles PRK, but uses alcohol to loosen the corneal surface. * Epi-LASIK:
Epi-LASIK Epi-LASIK is a refractive surgery technique designed to reduce a person's dependency on eyeglasses and contact lenses. Invented by Dr. Ioannis Pallikaris, the technique is basically an automatic LASEK without alcohol; it can be better considered as ...
is also used to correct hyperopia. In this procedure, use of epikeratome eliminates the use of alcohol. * Laser thermal keratoplasty (LTK):
Laser thermal keratoplasty Laser thermal keratoplasty is a non-contact laser refractive surgery. __TOC__ Procedure The procedure employs a holmium laser to place a ring of concentric laser burns on the cornea between 6 mm and 7 mm in diameter. These burns cause a ...
is a laser based non-destructive refractive procedure used to correct hyperopia and presbyopia. It uses Thallium-Holmium-Chromium (THC): YAG laser. IOL implantation * Aphakia correction: High degree hypermetropia due to absence of lens (aphakia) is best corrected using intraocular lens implantation. * Refractive lens exchange (RLE): A variation of
cataract surgery Cataract surgery, also called lens replacement surgery, is the removal of the natural lens of the eye (also called "crystalline lens") that has developed an opacification, which is referred to as a cataract, and its replacement with an intraocu ...
where the natural
crystalline lens The lens, or crystalline lens, is a transparent biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. By changing shape, it functions to change the focal length of the eye so that it can ...
is replaced with an artificial
intraocular lens Intraocular lens (IOL) is a lens implanted in the eye as part of a treatment for cataracts or myopia. If the natural lens is left in the eye, the IOL is known as phakic, otherwise it is a pseudophakic, or false lens. Such a lens is typically i ...
; the difference is the existence of abnormal ocular anatomy which causes a high refractive error. * Phakic IOL:
Phakic intraocular lens A phakic intraocular lens (PIOL) is a special kind of intraocular lens that is implanted surgically into the eye to correct myopia (nearsightedness). It is called "phakic" (meaning "having a lens") because the eye's natural lens is left untouched. ...
are lenses that implanted inside eye without removing the normal crystalline lens. Phakic IOLs can be used to correct hypermetropia up to +20 diopters. Non laser procedures * Conductive keratoplasty (CK):
Conductive keratoplasty 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. It is used to treat mild to moderate hyperopia. It is a non-invasive alternative to ...
is a non laser refractive procedure used to correct presbyopia and low hypermetropia (+0.75D to +3.25D) with or without astigmatism (up to 0.75D). It uses radiofrequency energy to heat and shrink corneal collagen tissue. CK is contraindicated in pregnant/breastfeeding women, central corneal dystrophies and
scarring A scar (or scar tissue) is an area of fibrous tissue that replaces normal skin after an injury. Scars result from the biological process of wound repair in the skin, as well as in other organs, and tissues of the body. Thus, scarring is a na ...
, history of
herpetic keratitis Herpetic simplex keratitis is a form of keratitis caused by recurrent herpes simplex virus (HSV) infection in the cornea. It begins with infection of epithelial cells on the surface of the eye and retrograde infection of nerves serving the corne ...
, type 1 diabetes etc. * Automated lamellar keratoplasty (ALK): Hyperopic
automated lamellar keratoplasty Automated lamellar keratoplasty (ALK), also known as keratomileusis in situ, is a non-laser lamellar refractive procedure used to correct high degree refractive errors. This procedure can correct large amounts of myopia and hyperopia. However, th ...
(H-ALK) and Homoplastic ALK are ALK procedures that corrects low to moderate hyperopia. Poor predictability and the risk of complications limits usefulness of these procedures. * Keratophakia and epi-keratophakia are another two non laser surgical procedures used to correct hypermetropia. Keratophakia is a surgical technique developed by Barraquer for treating high hypermetropia and aphakia. Poor predictability and induced irregular
astigmatism Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at nig ...
are complications of these procedures.


Etymology

The term ''hyperopia'' comes from
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
ὑπέρ ''hyper'' "over" and ὤψ ''ōps'' "sight" (
GEN Gen may refer to: * ''Gen'' (film), 2006 Turkish horror film directed by Togan Gökbakar * Gen (Street Fighter), a video game character from the ''Street Fighter'' series * Gen Fu, a video game character from the ''Dead or Alive'' series * Gen l ...
ὠπός ''ōpos'').


References


External links

{{Portal bar, Medicine Disorders of ocular muscles, binocular movement, accommodation and refraction Wikipedia medicine articles ready to translate Wikipedia neurology articles ready to translate