Hyperopia, also known as
farsightedness,
longsightedness or
hypermetropia, is a
defectDefect, Defects, or defected may refer to:* Defect , a characteristic of a polyhedron* The Defects, Northern-Irish punk rock band* Defected Records, a music label* Crystallographic defect, a structural imperfection in a crystal...
of
visionThe visual system is the part of the central nervous system which enables organisms to see.It interprets the information from visible light to build a representation of the world surrounding the body...
caused by an imperfection in the
eyeEyes are organs that detect light, and send electrical impulses along the optic nerve to the visual and other areas of the brain. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system...
(often when the eyeball is too short or when the
lensThe lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a sharp real...
cannot become round enough), causing difficulty
focusingIn psychotherapy-related disciples, the term focusing is used to refer to the simple matter of holding a kind of open, non-judging attention to something which is directly experienced but is not yet in words. Focusing can be used to become clear on what one feels or wants...
on near objects, and in extreme cases causing a sufferer to be unable to focus on objects at any
distanceDistance is a numerical description of how far apart objects are. In physics or everyday discussion, distance may refer to a physical length, a period of time, or an estimation based on other criteria . In mathematics, a distance function or metric is a generalization of the concept of physical...
. As an object moves toward the eye, the eye must increase its power to keep the image in focus on the retina.
Hyperopia, also known as
farsightedness,
longsightedness or
hypermetropia, is a
defectDefect, Defects, or defected may refer to:* Defect , a characteristic of a polyhedron* The Defects, Northern-Irish punk rock band* Defected Records, a music label* Crystallographic defect, a structural imperfection in a crystal...
of
visionThe visual system is the part of the central nervous system which enables organisms to see.It interprets the information from visible light to build a representation of the world surrounding the body...
caused by an imperfection in the
eyeEyes are organs that detect light, and send electrical impulses along the optic nerve to the visual and other areas of the brain. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system...
(often when the eyeball is too short or when the
lensThe lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a sharp real...
cannot become round enough), causing difficulty
focusingIn psychotherapy-related disciples, the term focusing is used to refer to the simple matter of holding a kind of open, non-judging attention to something which is directly experienced but is not yet in words. Focusing can be used to become clear on what one feels or wants...
on near objects, and in extreme cases causing a sufferer to be unable to focus on objects at any
distanceDistance is a numerical description of how far apart objects are. In physics or everyday discussion, distance may refer to a physical length, a period of time, or an estimation based on other criteria . In mathematics, a distance function or metric is a generalization of the concept of physical...
. As an object moves toward the eye, the eye must increase its 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.
People with hyperopia can experience
blurred visionIn optics, defocus is the one aberration familiar to nearly everyone who has ever needed eyeglasses or used a camera, videocamera, microscope, telescope, or binoculars, as it simply means out of focus. Optically, defocus refers to a translation along the optical axis away from the plane or surface...
,
asthenopiaAsthenopia or eye strain is an ophthalmological condition that manifests itself through nonspecific symptoms such as fatigue, red eyes, pain in or around the eyes, blurred vision, headache and occasional double vision...
, accommodative dysfunction,
binocular dysfunctionBinocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bini for double, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a...
,
amblyopiaAmblyopia, otherwise known as lazy eye, is a disorder of the visual system that is characterized by poor or indistinct vision in an eye that is otherwise physically normal, or out of proportion to associated structural abnormalities...
, and
strabismusStrabismus is a condition in which the eyes are not properly aligned with each other...
.
Hyperopia is often confused with
presbyopiaPresbyopia describes the condition where the eye exhibits a progressively diminished ability to focus on near objects with age...
, another condition that frequently causes blurry near vision. 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. It is also sometimes referred to as farsightedness, since in otherwise normally-sighted persons it makes it more difficult to focus on near objects than on far objects.
The causes of hyperopia are typically genetic and involve an eye that is too short or a cornea that is too flat, so that images focus at a point behind the retina. People with hyperopia can usually see distant objects well, but have trouble focusing on nearby objects.
Classification of hyperopia
Hyperopia is typically classified according to clinical appearance, its severity, or how it relates to the eye's
accommodative statusAccommodation is the process by which the vertebrate :eye changes optical power to maintain a clear image on an object as its distance changes....
.
Classification by clinical appearance
- Simple hyperopia
- Pathological hyperopia
- Functional hyperopia
Diagnosis
Visual acuityVisual acuity is acuteness or clearness of vision, especially form vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain....
is affected according to the amount of hyperopia, as well as the patient's age, visual demands, and accommodative ability.
Treatment
Various
eye care professionalAn eye care professional is an individual who provides a service related to the eyes or vision. It is a general term that can refer to any healthcare worker involved in eye care, from one with a small amount of post-secondary training to practitioners with a doctoral level of education.-Current...
s, including ophthalmologists, optometrists, orthoptists, and
opticianAn optician is a licensed health care practitioner who provides lenses for the correction of a refractive error. Corrective lenses may be contact lenses, spectacles lenses, low vision aids or ophthalmic prosthetics to those who are partially sighted...
s, are involved in the treatment and management of hyperopia. At the conclusion of an
eye examinationAn eye examination is a battery of tests performed by an ophthalmologist, optometrist, or orthoptist assessing vision and ability to focus on and discern objects, as well as other tests and examinations pertaining to the eyes....
, an eye doctor may provide the patient with an
eyeglass prescriptionAn eyeglass prescription is a written order by an optometrist, ophthalmologist, orthoptist or an optician for eyeglasses. It specifies the refractive power to which the eyeglasses are to be made in order to correct blurred vision due to refractive errors, including myopia, hyperopia, astigmatism,...
for
corrective lensA corrective lens is a lens worn in front of the eye, mainly used to treat myopia, hyperopia, astigmatism, and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye. Contact lenses are worn directly on the surface of the eye...
es.
Minor amounts of hyperopia are sometimes left uncorrected. However, larger amounts may be corrected with convex lenses in eyeglasses or contact lenses. Convex lenses have a positive
dioptric valueA dioptre, or diopter, is a unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres . For example, a 3 dioptre lens brings parallel rays of light to focus at 1/3 metre...
, which causes the light to focus closer than its normal range.
Hyperopia is sometimes correctable with various
refractive surgeryRefractive eye surgery is any 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 or cataract surgery. The most common methods today use excimer lasers to...
procedures (
LASIKLASIK or Lasik is a type of refractive surgery for correcting myopia, hyperopia, and astigmatism. LASIK is performed by ophthalmologists using a laser...
). It can also be corrected with special concave lenses.
External links