Long-sightedness: why you see badly up close (and sometimes in the distance too)

The name is misleading. ‘Long-sighted’ seems to mean ‘someone who sees far’: if the short-sighted person sees well up close, the long-sighted person should see well in the distance. This is partly true, but only as long as the eye can compensate. Long-sightedness works silently for years and makes itself felt when the reserves start to run down.

It is also a very widespread defect. In the European E3 consortium studies, which pooled almost 62,000 adults, about one in four had long-sightedness of at least one dioptre¹. And at the beginning of life it is almost the rule: most children are born long-sighted².

In this article

1. What long-sightedness is: a slightly short eye
2. Why you see badly up close
3. And sometimes in the distance too: what changes with age
4. How common it is
5. Long-sightedness in children
6. Long-sightedness and angle-closure glaucoma
7. How it is corrected
8. Frequently asked questions
9. Sources

What long-sightedness is: a slightly short eye

To see sharply, light has to be focused exactly on the retina, the sensitive membrane at the back of the eye. The eye’s two natural lenses, the cornea at the front and the lens inside, are calibrated to the length of the eyeball. In long-sightedness the system is too weak for that length, because the eye is shorter than needed or because the cornea and lens are not powerful enough: images would be focused behind the retina.

The eye, however, has a resource. The lens is elastic and can increase its power, like the autofocus of a camera: this is accommodation, the same one we all use to go from far to near. The long-sighted person already uses it to look into the distance, and uses even more of it to read.

In the first years of life, most of us are in this situation. A review on the role of the lens in the development of vision recalls that most children are long-sighted in the early years and that this long-sightedness is usually lost with growth. The eye goes from about 15 millimetres in premature newborns to about 24 in the young adult: a lengthening that would be worth more than 40 dioptres, but which the cornea and lens compensate for by changing their power². Those who remain long-sighted have not fully completed this journey.

Why you see badly up close

As long as the lens is young and elastic, a long-sighted person can see well at all distances without noticing the effort. In children part of the long-sightedness can remain entirely hidden: in a retrospective study of 150 long-sighted children, the defect was ‘latent’ in 35% of cases, that is, it showed up only after drops that temporarily relax focusing (cycloplegia)⁵. This is why studies on children, like those cited further on, measure the dioptres after these drops⁸.

Continuous focusing effort, however, has a cost, which is felt above all up close. A 2026 review on children with moderate long-sightedness concludes that many of them do not see up close as well as their peers and have more difficulty with close vision, early reading and writing skills, reading and attention⁶.

And sometimes in the distance too: what changes with age

The ability to accommodate is not eternal. A review of the mechanisms of focusing describes a steady decline starting from late childhood; accuracy remains good until about 40, when the amplitude of accommodation falls below what is needed for normal near work³. This is presbyopia, which comes to everyone.

For long-sighted people presbyopia adds to a defect that was already using up part of the reserves: difficulties up close tend to be felt sooner, and when the reserves are no longer enough distance vision also loses sharpness. In addition, in the middle-age years refraction tends to shift towards long-sightedness even in those who had none when young². The differences between long-sightedness and presbyopia can be found in the article on presbyopia, and the comparison with the other defects in short-sightedness, long-sightedness, astigmatism and presbyopia.

How common it is

Estimates change with the threshold and with age. A 2018 worldwide meta-analysis reports long-sightedness in 30.9% of adults and 4.6% of children, with European values lower than the world average in adults (23.1%), but with a very wide margin of uncertainty⁴. The E3 consortium figure, 25.2% of European adults with at least one dioptre, comes instead from 15 European population-based studies analysed together¹.

Long-sightedness in children

A little long-sightedness, in the early years, is normal². When it is high, however, it can interfere with the development of vision. A 2026 review of studies that followed children from the age of 6–24 months found that long-sightedness of at least +3.5 dioptres between 8 and 12 months was associated with a much higher risk of lazy eye (amblyopia) and of accommodative esotropia, a squint in which the eye turns towards the nose because of the focusing effort. Glasses prescribed early reduced the risk of lazy eye in some studies, with an overall effect judged to be moderate⁷. In the retrospective study cited above, children with long-sightedness of at least 3.5 dioptres had a 5.2 times higher risk of squint and a 3.7 times higher risk of amblyopia⁵.

It is on precisely this point that the evidence is still incomplete: according to the 2026 review, it is not clear whether correcting moderate long-sightedness allows children to recover from difficulties with near vision, reading and attention, and more studies are needed⁶. We discuss this in the article on long-sightedness in children.

Long-sightedness and angle-closure glaucoma

In some people the angle through which the fluid that nourishes the front of the eye drains is narrow, and can close; long-sighted eyes are among those in which this happens¹⁰. A review published in The Lancet lists older age, long-sightedness and East Asian origin as the main risk factors for primary angle-closure glaucoma⁹. The acute form is an emergency: the most common cause is a blockage of the passage of the fluid in eyes with a narrow angle, like those of long-sighted people, and the pressure rises suddenly¹⁰. We discuss this in the article on open-angle and angle-closure glaucoma.

How it is corrected

Long-sightedness is corrected with converging lenses, which have the plus sign on the prescription: glasses or contact lenses add the power that is missing and spare the lens the work of compensating. Refractive surgery techniques also exist. Whether and when to correct mild long-sightedness, in an adult without symptoms or in a child, is a decision made with the ophthalmologist, taking into account age, dioptres and how one sees.

Frequently asked questions

Does long-sightedness get worse with age?

Often it becomes more evident. Accommodation declines from late childhood and by about 40 it is no longer enough for near vision³; moreover, in middle age refraction tends to shift towards long-sightedness².

What is the difference between long-sightedness and presbyopia?

Long-sightedness depends mainly on the length of the eye and exists from birth; presbyopia is the age-related loss of accommodation, which affects everyone^2,3. The two conditions can add up.

Do all long-sighted children need glasses?

No: a little long-sightedness is normal in the early years and tends to reduce with growth². High long-sightedness, however, is associated with lazy eye and squint⁷, while for moderate long-sightedness the evidence on the benefits of glasses is still uncertain⁶. The decision is for the ophthalmologist.

Can long-sightedness cause glaucoma?

It does not cause it directly, but the long-sighted eye more often has a narrow angle, and this is one of the main risk factors for angle closure^9,10.

Long-sightedness usually makes no noise: the lens compensates for it, as long as it can. Knowing about it helps to read the right signs in children, to put a name to the near-vision tiredness that arrives with the years and to recognise the sudden red, painful eye, when there is no time to lose.