Farsightedness (hyperopia): what it is, causes and symptoms

The diagnosis of "hyperopia" often comes as a surprise: a person sees reasonably well at a distance and does not understand where the unfamiliar word came from. It can be understood calmly, step by step.

What farsightedness and hyperopia are

Farsightedness (hyperopia, also called "hypermetropia") is a refractive error in which objects located far away are seen better, while near objects are seen poorly. The key feature of the name is precisely the difficulty with near vision: even if a person also sees poorly at a distance, the diagnosis of "farsightedness" may still be given. Approximately every fourth person on Earth has this refractive error.

Age-related farsightedness, or presbyopia, is distinguished separately: it is associated with hardening of the lens — the transparent lens inside the eye — and a person with presbyopia alone sees well at a distance. Hyperopia can affect both eyes; one of the causes is a reduced axial length of the eyeball.

How light refraction works in hyperopia

The cornea — the anterior transparent membrane — and the lens refract light rays so that they converge at a focus on the retina, the light-sensitive layer at the back of the eye. In hyperopia at rest of accommodation, that is, without strain of the eye, the image is focused not on the retina but behind it. This is why near objects are blurry.

At a young age, with mild farsightedness, the eye often copes: the muscles tense, the lens changes its curvature, and the image falls on the retina. This latent form causes no visual complaints, but muscle strain leads to rapid eye fatigue, headache and nausea, and over time the condition becomes manifest.

Causes of hyperopia

The causes of hyperopia are related to how the eye focuses light: a reduced axial length of the eyeball, an altered shape of the cornea, weak congenital refractive power of the lens or cornea, and hardening of the lens with age. Almost all infants are farsighted, but as the eye grows this resolves in most; if vision does not return to normal on its own, it is called congenital farsightedness.

Farsightedness is often passed down from parents, and it cannot be prevented. Very rarely it is caused by other conditions, such as diabetes mellitus or an eye tumor. Age-related farsightedness is a natural condition: the lens's ability to change curvature decreases from about age 25, by age 40–50 this can reduce visual acuity when reading at a distance of 25–30 cm, and by age 65 the eye almost loses accommodation.

Symptoms of farsightedness in adults

Farsightedness occurs at any age but often affects people over 40. Near objects — words in a book, images on a screen — appear blurry, and if they are moved farther from the eyes they are seen more clearly. The eyes become tired after reading or working at a computer, and headaches appear. Common signs of refractive errors also include double vision, haze, glare and halos around bright lights, and the need to squint.

How hyperopia is diagnosed

Vision testing is usually performed by an optometrist — a specialist in assessing vision and prescribing glasses. The person is asked to look at lights or read letters while different lenses are placed in front of the eye. The doctor shines a light into the eye, assessing its posterior part, and may instill drops that dilate the pupil. The examination includes:

• testing visual acuity at different distances with and without correction;
• trial lens selection during the examination;
• examination of the posterior part of the eye using light;
• pupil-dilating drops for a full examination.

When to see an ophthalmologist

You should see a specialist if an adult or a child develops signs of farsightedness: blurriness at near, fatigue and headache after working with small objects or a screen. If a person already wears glasses or lenses and notices changes, a new examination is needed. A separate reason is the latent form, fatigue and headache without obvious deterioration of vision. Young children with marked farsightedness have a higher likelihood of strabismus and amblyopia.

Farsightedness itself is not a reason to call an ambulance; 103/112 — for signs that threaten life, for example signs of stroke or heart attack.

Hyperopia is a condition in which the eye focuses light behind the retina, so near objects are seen worse than distant ones. This material is for reference and does not replace a doctor's consultation: the final answer about your vision is given by an examination by a specialist.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer