Farsightedness

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Far-sightedness
Other namesHypermetropia, hyperopia, longsightedness, long-sightedness [1]
Hypermetropia color.svg
Far-sightedness without (top) and with lens correction (bottom)
Specialty Ophthalmology, optometry
Symptoms Near blur, Distance and near blur, Asthenopia [2]
Complications Accommodative dysfunction, binocular dysfunction, amblyopia, strabismus [3]
CausesAxial length of eyeball is too short, lens or cornea is flatter than normal, aphakia [2]
Risk factors Ageing, hereditary [2]
Diagnostic method Eye exam
Differential diagnosis Amblyopia, retrobulbar optic neuropathy, retinitis pigmentosa sine pigmento [4]
Treatment Eyeglasses, contact lenses, refractive surgeries, IOL implantation [2]
Frequency~7.5% (US) [5]

Far-sightedness, also known as long-sightedness, hypermetropia, and hyperopia, is a condition of the eye where distant objects are seen clearly but near objects appear blurred. This blur is due to incoming light being focused behind, instead of on, the retina due to insufficient accommodation by the lens. [6] Minor hypermetropia in young patients is usually corrected by their accommodation, without any defects in vision. [2] But, due to this accommodative effort for distant vision, people may complain of eye strain during prolonged reading. [2] [7] If the hypermetropia is high, there will be defective vision for both distance and near. [2] People may also experience accommodative dysfunction, binocular dysfunction, amblyopia, and strabismus. [3] Newborns are almost invariably hypermetropic, but it gradually decreases as the newborn gets older. [6]

Contents

There are many causes for this condition. It may occur when the axial length of eyeball is too short or if the lens or cornea is flatter than normal. [2] Changes in refractive index of lens, alterations in position of the lens or absence of lens are the other main causes. [2] Risk factors include a family history of the condition, diabetes, certain medications, and tumors around the eye. [5] [4] It is a type of refractive error. [5] Diagnosis is based on an eye exam. [5] [8]

Management can occur with eyeglasses, contact lenses, or refractive corneal surgeries. [2] Glasses are easiest while contact lenses can provide a wider field of vision. [2] Surgery works by changing the shape of the cornea. [5] Far-sightedness primarily affects young children, with rates of 8% at 6 years old and 1% at 15 years old. [9] It then becomes more common again after the age of 40, known as presbyopia, affecting about half of people. [4] The best treatment option to correct hypermetropia due to aphakia is IOL implantation. [2]

Other common types of refractive errors are near-sightedness, astigmatism, and presbyopia. [10]

Signs and symptoms

In young patients, mild hypermetropia may not produce any symptoms. [2] The signs and symptoms of far-sightedness include blurry vision, frontal or fronto temporal headaches, eye strain, tiredness of eyes etc. [2] The common symptom is eye strain. Difficulty seeing with both eyes (binocular vision) may occur, as well as difficulty with depth perception. [1] The asthenopic symptoms and near blur are usually seen after close work, especially in the evening or night. [6]

Complications

Far-sightedness can have rare complications such as strabismus and amblyopia. At a young age, severe far-sightedness can cause the child to have double vision as a result of "over-focusing". [11]

Hypermetropic patients with short axial length are at higher risk of developing primary angle closure glaucoma, so, routine gonioscopy and glaucoma evaluation is recommended for all hypermetropic adults. [12]

Causes

Simple hypermetropia, the most common form of hypermetropia, is caused by normal biological variations in the development of eyeball. [2] Aetiologically, causes of hypermetropia can be classified as:

Far-sightedness is often present from birth, but children have a very flexible eye lens, which helps to compensate. [14] In rare instances hyperopia can be due to diabetes, and problems with the blood vessels in the retina. [1]

Diagnosis

Far-sighted vision on left, normal vision on right Hyperopia comparison.jpg
Far-sighted vision on left, normal vision on right
Human eye cross-section Human eye cross-sectional view grayscale.png
Human eye cross-section

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 test, which examines the cornea, conjunctiva, anterior chamber, and iris. [15] [16]

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 can see objects close to the eye in detail and does learn at an early age to see objects in detail.[ medical citation needed ]

Classification

Choroid folds in high hyperopia (fluorescein angiography) 1999 Choroid folds.jpg
Choroid folds in high hyperopia (fluorescein angiography)

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

Clinical classification

There are three clinical categories of hyperopia. [3]

  • 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: [3]

  • Low: Refractive error less than or equal to +2.00 diopters (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: [7] [2]

  • Total hypermetropia: It is the total amount of hyperopia which is obtained after complete relaxation of accommodation using cycloplegics like atropine.
  • 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) [7]

Treatment

Corrective lenses

The simplest form of treatment for far-sightedness is the use of corrective lenses, i.e. eyeglasses or contact lenses. [17] [18] Eyeglasses used to correct far-sightedness have convex lenses. [19]

Surgery

There are also surgical treatments for far-sightedness:

Laser procedures

IOL implantation

Non laser procedures

Etymology

The term hyperopia comes from Greek ὑπέρ hyper "over" and ὤψ ōps "sight" ( GEN ὠπός ōpos). [27]

Related Research Articles

<span class="mw-page-title-main">Myopia</span> Problem with distance vision

Myopia, also known as near-sightedness and short-sightedness, is an eye disease where light from distant objects 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 headaches and eye strain. Severe myopia is associated with an increased risk of macular degeneration, retinal detachment, cataracts, and glaucoma.

<span class="mw-page-title-main">LASIK</span> Corrective ophthalmological surgery

Laser-Assisted in Situ Keratomileusis (LASIK), commonly referred to as laser eye surgery or laser vision correction, is a type of refractive surgery for the correction of myopia, hyperopia, and an actual cure for astigmatism, since it is in the cornea. LASIK surgery is performed by an ophthalmologist who uses a laser or microkeratome to reshape the eye's cornea in order to improve visual acuity.

<span class="mw-page-title-main">Presbyopia</span> Medical condition associated with aging of the eye

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, it affects many adults over the age of 40. A common sign of presbyopia is difficulty reading small print which results in having to hold reading material farther away. Other symptoms associated can be headaches and eyestrain. Different people will have different degrees of problems. Other types of refractive errors may exist at the same time as presbyopia. This condition is similar to hypermetropia or far-sightedness which starts in childhood and exhibits similar symptoms of blur in the vision for close objects.

<span class="mw-page-title-main">Photorefractive keratectomy</span> Refractive eye surgery procrdure

Photorefractive keratectomy (PRK) and laser-assisted sub-epithelial keratectomy (LASEK) are laser eye surgery procedures intended to correct a person's vision, reducing dependency on glasses or contact lenses. LASEK and PRK permanently change the shape of the anterior central cornea using an excimer laser to ablate a small amount of tissue from the corneal stroma at the front of the eye, just under the corneal epithelium. The outer layer of the cornea is removed prior to the ablation.

<span class="mw-page-title-main">Eye surgery</span> Surgery performed on the eye or its adnexa

Eye surgery, also known as ophthalmic surgery or ocular surgery, is surgery performed on the eye or its adnexa. Eye surgery is part of ophthalmology and is performed by an ophthalmologist or eye surgeon. The eye is a fragile organ, and requires due care before, during, and after a surgical procedure to minimize or prevent further damage. An eye surgeon is responsible for selecting the appropriate surgical procedure for the patient, and for taking the necessary safety precautions. Mentions of eye surgery can be found in several ancient texts dating back as early as 1800 BC, with cataract treatment starting in the fifth century BC. It continues to be a widely practiced class of surgery, with various techniques having been developed for treating eye problems.

<span class="mw-page-title-main">Radial keratotomy</span> Refractive surgical procedure to correct myopia (nearsightedness

Radial keratotomy (RK) is a refractive surgical procedure to correct myopia (nearsightedness). It was developed in 1974 by Svyatoslav Fyodorov, a Russian ophthalmologist. It has been largely supplanted by newer, more accurate operations, such as photorefractive keratectomy, LASIK, Epi-LASIK and the phakic intraocular lens.

<span class="mw-page-title-main">Refractive surgery</span> Surgery to treat common vision disorders

Refractive surgery is optional eye surgery used to improve the refractive state of the eye and decrease or eliminate dependency on glasses or contact lenses. This can include various methods of surgical remodeling of the cornea (keratomileusis), lens implantation or lens replacement. The most common methods today use excimer lasers to reshape the curvature of the cornea. Refractive eye surgeries are used to treat common vision disorders such as myopia, hyperopia, presbyopia and astigmatism.

<span class="mw-page-title-main">Intraocular lens</span> Lens implanted in the eye to treat cataracts or myopia

An Intraocular lens (IOL) is a lens implanted in the eye usually as part of a treatment for cataracts or for correcting other vision problems such as short sightedness and long sightedness; a form of refractive surgery. If the natural lens is left in the eye, the IOL is known as phakic, otherwise it is a pseudophakic lens. Both kinds of IOLs are designed to provide the same light-focusing function as the natural crystalline lens. This can be an alternative to LASIK, but LASIK is not an alternative to an IOL for treatment of cataracts.

<span class="mw-page-title-main">Refractive error</span> Problem with focusing light accurately on the retina due to the shape of the eye

Refractive error is a problem with focusing light accurately on the retina due to the shape of the eye and/or cornea. The most common types of refractive error are near-sightedness, far-sightedness, astigmatism, and presbyopia. Near-sightedness results in far away objects being blurry, far-sightedness and presbyopia result in close objects being blurry, and astigmatism causes objects to appear stretched out or blurry. Other symptoms may include double vision, headaches, and eye strain.

<span class="mw-page-title-main">Phakic intraocular lens</span> Lens implanted in eye in addition to the natural lens

A phakic intraocular lens (PIOL) is an intraocular lens that is implanted surgically into the eye to correct refractive errors without removing the natural lens. Intraocular lenses that are implanted into eyes after the eye's natural lens has been removed during cataract surgery are known as pseudophakic.

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 ability to maintain focus (accommodation), high degree of farsightedness (hyperopia), and a deep anterior chamber. Complications include detachment of the vitreous or retina, and glaucoma.

Epikeratophakia is a refractive surgical procedure in which a lamella of a donor cornea is transplanted onto the anterior surface of the patient's cornea. A lamellar disc from a donor cornea is placed over the de-epithelialized host cornea and sutured into a prepared groove on the host cornea. Indications include treatment of keratoconus, refractive errors like myopia and high hypermetropia including aphakia, which cannot be corrected with conservative methods.

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, the resultant change is not as predictable as with other procedures.

<span class="mw-page-title-main">Emmetropia</span> State of vision

Emmetropia is the state of vision in which a faraway object at infinity is in sharp focus with the ciliary muscle in a relaxed state. That condition of the normal eye is achieved when the refractive power of the cornea and eye lens and the axial length of the eye balance out, which focuses rays exactly on the retina, resulting in perfectly sharp distance vision. A human eye in a state of emmetropia requires no corrective lenses for distance; the vision scores well on a visual acuity test.

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 other types of eye surgery. It uses the same principles of laser thermokeratoplasty (LTK) and radial keratocoagulation, although the former uses holmium laser and the latter a 700°C needle to correct hyperopia.

Vision of humans and other organisms depends on several organs such as the lens of the eye, and any vision correcting devices, which use optics to focus the image.

Laser blended vision is a laser eye treatment which is used to treat presbyopia or other age-related eye conditions. It can be used to help people that simply need reading glasses, and also those who have started to need bifocal or varifocal spectacle correction due to ageing changes in the eye. It can be used for people who are also short-sighted (myopia) or long-sighted (hyperopia) and who also may have astigmatism.

Peter S. Hersh is an American ophthalmologist and specialist in LASIK eye surgery, keratoconus, and diseases of the cornea. He co-authored the article in the journal Ophthalmology that presented the results of the study that led to the first approval by the U.S. Food and Drug Administration (FDA) of the excimer laser for the correction of nearsightedness in the United States. Hersh was also medical monitor of the study that led to approval of corneal collagen crosslinking for the treatment of keratoconus.

The eye, like any other optical system, suffers from a number of specific optical aberrations. The optical quality of the eye is limited by optical aberrations, diffraction and scatter. Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of methods to measure and correct ocular astigmatism. It has only recently become possible to measure the aberrations of the eye and with the advent of refractive surgery it might be possible to correct certain types of irregular astigmatism.

Post-LASIK ectasia is a condition similar to keratoconus where the cornea starts to bulge forwards at a variable time after LASIK, PRK, or SMILE corneal laser eye surgery. However, the physiological processes of post-LASIK ectasia seem to be different from keratoconus. The visible changes in the basal epithelial cell and anterior and posterior keratocytes linked with keratoconus were not observed in post-LASIK ectasia.

References

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  17. ↑ Chou, Roger; Dana, Tracy; Bougatsos, Christina (2011-02-01). "Introduction". Screening for Visual Impairment in Children Ages 1-5 Years: Systematic Review to Update the 2004 U.S. Preventive Services Task Force Recommendation (Report). Evidence Syntheses. Vol. 81. Rockville, MD: Agency for Healthcare Research and Quality. PMID   21542544. Archived from the original on 2017-09-08 – via PubMed Health.
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