Farsightedness
The prescription nobody warned you about: what a "plus" number actually means
Most babies are born farsighted, and it usually corrects itself. Here's how to tell whether your child's plus number is one of those โ or one that needs glasses now.
Buddy's quick answer
Nearly every baby is born farsighted, averaging around +2.00 diopters, and that number normally drifts toward zero through the first five years as the eye grows. A high plus number โ commonly flagged once it's above roughly +3.50 to +4.50, depending on age โ is a different situation: it sits outside the range guidelines expect to self-correct, and it's linked to lazy eye and crossed eyes if left uncorrected. A +5.00 in one eye only, like the case that inspired this article, is above those thresholds at any age and unevenly split between the eyes, which is a second reason it's being taken seriously rather than watched.
The basics
What does a "plus" number actually mean?
A plus sign in front of a prescription number means hyperopia โ farsightedness. The lens is shaped to bend light inward so it focuses correctly on the retina; a minus sign (myopia, nearsightedness) does the opposite. The bigger the plus number, the harder the eye has to work to focus, whether on a book six inches away or a face across the room.
Why almost every baby starts out this way
Farsighted at birth is the default, not the exception
Most infants are born meaningfully farsighted, averaging around +2.00 D. Over the first year, and continuing more slowly through about age five, the eye grows โ its length increasing from roughly 17mm to 21mm โ and that growth pulls the focus point back toward normal. The American Academy of Ophthalmology calls this emmetropization, and by around age six the average child is still only mildly farsighted, about +0.75 D.
When the number stops being reassuring
How much farsightedness is "too much" at a given age?
Pediatric vision screening commonly uses age-banded cutoffs to separate ordinary childhood farsightedness from the amount considered a real risk factor โ worth treating rather than watching. The cutoff gets stricter as a child gets older, because normal farsightedness is supposed to be shrinking on its own: a number that's unremarkable at 18 months is a flag at four.
| Typical for age | Commonly flagged for a closer look | |
|---|---|---|
| 12โ30 months | Roughly +2.00 to +3.00 D | Above about +4.50 D |
| 2.5โ4 years | Roughly +1.50 to +2.50 D | Above about +4.00 D |
| 4+ years | Trending under +2.00 D, toward +0.75 D by six | Above about +3.50 D |
These bands are the kind commonly used in pediatric vision screening, not a single universal rule, and they mark when to look closer โ not a prescribing formula. A single +5.00 clears the "look closer" line at every age in this table.
Why doctors don't just wait and see
What a high number can lead to if it's left uncorrected
To see clearly through a high plus prescription, a child's eyes have to work harder to focus โ a reflex called accommodation. Because accommodation and eye-turning (convergence) are wired together, heavy accommodative effort can drag the eyes inward, and if a child can't counteract that pull, the result is accommodative esotropia, a form of crossed eyes. The American Academy of Ophthalmology notes the average hyperopic correction found in these cases is +4.75 D, in a typical range of +1.50 to +7.00 D โ putting a +5.00 prescription squarely inside the range where this actually happens, not at its edge. Separately, uncorrected high hyperopia is its own recognized risk factor for amblyopia (lazy eye): a consistently blurred image during early visual development can keep one eye from ever learning to see clearly.
It's not necessarily forever
Children whose hyperopia is on the lower side (under about +3.00 D) discontinue glasses at meaningfully higher rates than children with higher amounts, who tend to need correction for longer.
Myopia does the opposite
Nearsightedness typically worsens through childhood and the teen years. Ordinary childhood farsightedness does the reverse โ it shrinks. See our guide to childhood myopia for the contrast.
One eye can hide behind the other
A child with one strong eye and one weak eye can still seem fine day to day, because the brain simply favors the better eye โ which is exactly why the weaker eye needs its own correction, not just a passing overall grade.
Buddy-picked
Frames that hold up through a new prescription
Common questions
Farsightedness in kids โ the questions parents ask most
Is +5.00 a high prescription for a 3-year-old?
Yes. The age-based screening ranges pediatric eye doctors commonly use flag hyperopia above roughly +4.00 to +4.50 D at that age, so a single-eye +5.00 is above the range considered typical and self-correcting. Being in one eye only, rather than both, is a second reason it's being taken seriously.
Do farsighted kids grow out of it?
Often, if it's mild. Most children are born meaningfully farsighted and that number shrinks steadily over the first five years as the eye grows; by kindergarten the average child is only mildly farsighted, around +0.75 D. Higher amounts are less likely to fully resolve and more likely to need glasses for longer.
What's the difference between farsighted and nearsighted?
Farsighted (hyperopia, a plus number) means the eye focuses images behind the retina without help, making close-up focusing harder. Nearsighted (myopia, a minus number) is the opposite โ distance objects blur while close vision stays sharp. The two need opposite lens shapes to correct.
Can farsightedness cause crossed eyes?
Yes, in a specific way. A high uncorrected plus prescription forces extra focusing effort, and because focusing and eye-turning are linked, that effort can pull the eyes inward โ a condition called accommodative esotropia. Glasses that correct the farsightedness typically correct the eye-turning too.
Will my child need glasses forever?
Not necessarily. Children with lower amounts of hyperopia (under about +3.00 D) discontinue glasses at higher rates than children with higher prescriptions, who more often need correction for longer. Your child's eye doctor will re-check the number at follow-up visits and adjust from there.
Does a plus number mean my child can't see up close?
Not always โ and that's what makes farsightedness easy to miss. Young children can often focus hard enough to see clearly up close and even pass a basic eye chart despite a real prescription, because a child's focusing muscles are unusually strong. See our article on why a child can pass the eye chart and still need glasses.
Keep exploring
Helpful next reads
If your child passed a vision screening but still got a prescription, read why she read the chart perfectly and still needs glasses. For the exam itself, see how doctors test a toddler who can't talk and what happens at your child's first eye exam. If crossed eyes are part of the picture, read our guide to strabismus in kids. For the opposite end of the spectrum, see why nearsightedness gets worse with age. And for what your child's prescription paperwork should include, see our prescription guide.
Where this comes from
Sources
American Academy of Ophthalmology โ Refractive Development ยท American Academy of Ophthalmology โ Accommodative Esotropia ยท Review of Optometry โ Prescribing for Young Children
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