|Other names||Hypermetropia, hyperopia, longsightedness, long-sightedness|
|Far-sightedness without (top) and with lens correction (bottom)|
|Symptoms||Close objects appear blurry|
|Complications||Accommodative dysfunction, binocular dysfunction, amblyopia, strabismus|
|Causes||Too short an eyeball, misshapen lens or cornea|
|Risk factors||Family history|
|Diagnostic method||Eye exam|
|Differential diagnosis||Amblyopia, retrobulbar optic neuropathy, retinitis pigmentosa sine pigmento|
|Treatment||Eyeglasses, contact lenses, surgery|
Far-sightedness, also known hypermetropia, is a condition of the eye in which light is focused behind, instead of on, the retina. This results in close objects appearing blurry, while far objects may appear normal. As the condition worsens, objects at all distances may be blurry. Other symptoms may include headaches and eye strain. People may also experience accommodative dysfunction, binocular dysfunction, amblyopia, and strabismus.
The cause is an imperfection of the eyes. Often it occurs when the eyeball is too short, or the lens or cornea is misshapen. Risk factors include a family history of the condition, diabetes, certain medications, and tumors around the eye. It is a type of refractive error. Diagnosis is based on an eye exam.
Management can occur with eyeglasses, contact lenses, or surgery. Glasses are easiest while contact lenses can provide a wider field of vision. 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, affecting about half of people.
Signs and symptoms
The signs and symptoms of far-sightedness are blurry vision, headaches, and eye strain. The common symptom is eye strain. Difficulty seeing with both eyes (binocular vision) may occur, as well as difficulty with depth perception.
As hyperopia results from the visual image being focused behind the retina, it has two main causes:
- Low converging power of eye lens because of weak action of ciliary muscles
- Abnormal shape of the cornea
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, and problems with the blood vessels in the retina.
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.
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]
Hyperopia is typically classified according to clinical appearance, its severity, or how it relates to the eye's accommodative status.
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.
There are also three categories severity:
- Refractive error less than or equal to +2.00 diopters (D).
- Refractive error greater than +2.00 D up to +5.00 D.
- Refractive error greater than +5.00 D.
There are also surgical treatments for far-sightedness:
- Laser eye surgery to reshape the cornea, so that glasses or contact lenses are no longer needed.
- Refractive lens exchange (RLE)
- A variation of cataract surgery where the natural crystalline lens is replaced with an artificial intraocular lens; the difference is the existence of abnormal ocular anatomy which causes a high refractive error.
- Laser epithelial keratomileusis (LASEK)
- Resembles PRK, but uses alcohol to loosen the corneal surface.
- Lowth, Mary. "Long Sight (Hypermetropia)". Patient. Patient Platform Limited. Archived from the original on 2016-03-03. Retrieved 2016-02-26.
- "Facts About Hyperopia". NEI. July 2016. Archived from the original on 8 July 2017. Retrieved 11 July 2017.
- Moore, Bruce D.; Augsburger, Arol R.; Ciner, Elise B.; Cockrell, David A.; Fern, Karen D.; Harb, Elise (2008). "Optometric Clinical Practice Guideline: Care of the Patient with Hyperopia" (PDF). American Optometric Association. pp. 2–3, 10–11. Archived from the original (PDF) on 2006-07-17. Retrieved 2006-06-18.
- Kaiser, Peter K.; Friedman, Neil J.; II, Roberto Pineda (2014). The Massachusetts Eye and Ear Infirmary Illustrated Manual of Ophthalmology E-Book. Elsevier Health Sciences. p. 541. ISBN 9780323225274. Archived from the original on 2017-09-08.
- Castagno, VD; Fassa, AG; Carret, ML; Vilela, MA; Meucci, RD (23 December 2014). "Hyperopia: a meta-analysis of prevalence and a review of associated factors among school-aged children". BMC Ophthalmology. 14: 163. doi:10.1186/1471-2415-14-163. PMC 4391667. PMID 25539893.
- "Complications of long-sightedness". NHS Choices. National Health Service. 2014-07-09. Archived from the original on 2016-03-05. Retrieved 2016-02-26.
- "Normal, near-sightedness, and far-sightedness". MedlinePlus Medical Encyclopedia. Archived from the original on 2016-03-05. Retrieved 2016-02-26.
- "Farsightedness". MedlinePlus Medical Encyclopedia. Archived from the original on 2016-02-24. Retrieved 2016-02-26.
- "Slit-lamp exam". MedlinePlus Medical Encyclopedia. Archived from the original on 2016-03-05. Retrieved 2016-02-26.
- "Facts About Refractive Errors". National Eye Institute. October 2010. Archived from the original on 28 July 2016. Retrieved 30 July 2016.
- 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. 81. Rockville, MD: Agency for Healthcare Research and Quality. Archived from the original on 2017-09-08 – via PubMed Health.
- "Farsightedness (Hyperopia): Treatments". PubMed Health. U. S. National Library of Medicine. Archived from the original on 2017-09-08. Retrieved 2016-02-26.
- "Treating long-sightedness". NHS Choices. National Health Service. Archived from the original on 2016-03-05. Retrieved 2016-02-26.
- Settas, George; Settas, Clare; Minos, Evangelos; Yeung, Ian Yl (2012-01-01). "Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for hyperopia correction". Cochrane Database of Systematic Reviews. 6: CD007112. doi:10.1002/14651858.CD007112.pub3. ISSN 1469-493X. PMID 22696365. Lay summary – PubMed Health (2012-02-17).
- "Laser Eye Surgery". MedlinePlus. Archived from the original on 2016-03-06. Retrieved 2016-02-26.
- Alió, Jorge L.; Grzybowski, Andrzej; Romaniuk, Dorota (2014-12-10). "Refractive lens exchange in modern practice: when and when not to do it?". Eye and Vision. 1: 10. doi:10.1186/s40662-014-0010-2. ISSN 2326-0254. PMC 4655463. PMID 26605356.
- "hyperopia". Online Etymology Dictionary. Douglas Harper. Archived from the original on 2017-09-08.