, also known as farsightedness
, is a defect
caused by an imperfection in the eye
(often when the eyeball is too short or when the lens
cannot become round enough), causing inability to focus
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 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 vision, asthenopia, accommodative dysfunction, binocular dysfunction, amblyopia, and strabismus.
Hyperopia is often confused with presbyopia , 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.
Classification of hyperopia
Hyperopia is typically classified according to clinical appearance, its severity, or how it relates to the eye's accommodative status
Classification by clinical appearance
- Simple hyperopia
- Pathological hyperopia
- Functional hyperopia
is affected according to the amount of hyperopia, as well as the patient's age, visual demands, and accommodative ability.
Various eye care professionals
, including ophthalmologists
, orthoptists, and opticians
, are involved in the treatment and management of hyperopia. At the conclusion of an eye examination
, an eye doctor may provide the patient with an eyeglass prescription
for corrective lenses
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 value, which causes the light to focus closer than its normal range.
Hyperopia is sometimes correctable with various refractive surgery procedures. It can also be corrected with special concave lenses.