Farsightedness

Farsightedness, or hyperopia, is a common eye condition that causes blurry near vision due to the eye's inability to focus light correctly on the retina, often manageable with corrective lenses or surgery.

Overview

Farsightedness, also known as hyperopia, is an eye condition that causes blurry near vision. Individuals with this condition typically have more trouble seeing objects that are close up, such as when reading or using a computer, than objects that are far away, such as when driving.

For normal vision, light passes through the clear cornea at the front of the eye and is focused by the lens onto the surface of the retina, which is the lining of the back of the eye that contains light-sensing cells. In people with farsightedness, the eyeballs may be too short from front to back, or the cornea or lens may be abnormally shaped. These structural changes cause light entering the eye to be focused too far back, behind the retina instead of on its surface. This misalignment is what causes nearby objects to appear blurry. In some cases, one eye may be more farsighted than the other.

Most infants are born with a mild degree of farsightedness, which typically resolves on its own as the eyes grow. However, in some children, the condition persists or is more severe. Children with a severe degree of farsightedness, described as high hyperopia, are at an increased risk of developing other eye conditions, particularly amblyopia ("lazy eye") and strabismus (eyes that do not look in the same direction). These conditions can cause significant visual impairment.

Older adults also frequently experience difficulty seeing things close up; this condition is known as presbyopia. Presbyopia develops as the lens of the eye becomes thicker and less flexible with age and the muscles surrounding the lens weaken. Although it is sometimes described as "farsightedness," presbyopia is caused by a different mechanism than hyperopia and is considered a separate condition.

Symptoms & Complications

If not treated with corrective lenses or surgery, farsightedness can lead to various physical symptoms and functional difficulties. Common signs and symptoms include:

• Eye strain
• Excess tearing
• Squinting
• Frequent blinking
• Headaches
• Difficulty reading
• Problems with hand-eye coordination

It is important to note that some children with the eye changes characteristic of farsightedness do not notice any blurring of their vision or related signs and symptoms early in life. Other parts of the visual system are able to compensate, at least temporarily, for the changes that would otherwise cause light to be focused in the wrong place.

Causes & Risk Factors

Genetic Factors

Farsightedness is a complex condition. Multiple genetic variations, each with a small effect, likely influence whether a person is farsighted. Few genes associated with the condition have been identified, and none of the identified genes appears to play a major role in the development of farsightedness. At least some of the genes that influence farsightedness play roles in eye development, particularly in determining the length of the eyeball from front to back (also known as the axial length).

In many farsighted people, this vision problem is not part of a larger genetic syndrome. However, farsightedness (especially high hyperopia) can be a feature of other disorders with a genetic cause. Genetic conditions with farsightedness as a characteristic feature include:

• Microphthalmia
• Achromatopsia
• Aniridia
• Leber congenital amaurosis
• X-linked juvenile retinoschisis
• Senior-Løken syndrome
• Gorlin-Chaudhry-Moss syndrome
• Down syndrome
• Fragile X syndrome

Environmental Factors

It is possible that environmental factors also contribute to a person's risk of being farsighted, but these have not been well-studied.

Frequency

Farsightedness is a relatively common vision abnormality, although it is much less common than nearsightedness (myopia) or presbyopia. The prevalence of hyperopia decreases with age: most infants are farsighted at birth, but less than 4 percent of children have the condition at age 1. The prevalence continues to decrease into adulthood. Most cases are mild.

For unknown reasons, farsightedness is reported more frequently among Native Americans, African Americans, and Pacific Islanders than in people of other backgrounds.

Inheritance

Farsightedness is a complex condition that usually does not have a clear pattern of inheritance. The risk of developing this condition is greater for relatives of affected individuals (such as siblings or children) as compared to the general public.

When farsightedness is a feature of a genetic syndrome, it follows the inheritance pattern of that syndrome.

Other Names for This Condition

• Far-sightedness
• Farsighted
• Hypermetropia
• Hyperopia
• Long-sighted
• Long-sightedness