What is Hyperopia and What Causes it?
Hyperopia is a common eye problem that most people know better as "far-sightedness." Most people have experienced at least temporary far-sightedness after having their eyes dilated with the drops that the eye doctor gives them. However, some people experience chronic problems with hyperopia just like others experience long-term problems with myopia (nearsightedness). A person with hyperopia can usually see things that are far away clearly, but they have trouble making out details of things that are closer to them. However, because of the way that hyperopia works, many times someone with severe hyperopia will have problems with their close-up vision as well as their far-away vision. Hyperopia is so common that about 25% of people in the western world have it, compared to 40% of people in the western world who have myopia.
(People with hyperopia are unable to see near objects clearly, but they can often see distant objects just fine).
There are three types of hyperopia: axial, curvature, and refractive. Axial hyperopia is the most common type of far-sightedness, and it happens when the back of the eye is too close to the front of the eye. The image a person sees is reflected behind the retina, instead of right on the retina. This makes whatever the person sees out of focus. Curvature hyperopia is a problem with the lens of the eye, not the length. Just like a camera lens is usually curved, so is the lens of our eyes. When someone's cornea (eye lens) is too flat, the picture they're seeing can't be redirected properly against the retina. In refractive hyperopia, the lens of the eye just can't refract (bend) the light properly for optimal vision. Refractive hyperopia usually affects older people more than younger people, because the younger a person is, the more elastic their eye lens is. As we get older, our eye lenses become less elastic, and we cannot compensate for problems with our eyes as easily.
Far-sightedness is extremely common in children and babies, but they usually outgrow it as their eyes mature. It is often passed down through families, so there does seem to be a decent genetic component to hyperopia. Sometimes hyperopia is causes by the eyeballs being too small or by the eye not being able to focus properly. Other times, far-sightedness is a result of getting older, having frequent migraine headaches, or an injury or infection that affects the upper face area (like a sinus infection).
Signs and Symptoms
Hyperopia is not usually caught during routine vision screenings, because those usually only test for myopia (near-sightedness). An eye doctor will usually do a more thorough test, and this can help catch hyperopia. The symptoms of hyperopia are similar to other vision problems, including eye pain or strain, headaches, blurriness (of close objects), and sometimes crossed eyes. Children might only express their problems seeing with irritability, nervousness, or bad grades. People with hyperopia get headaches so frequently because the muscles that control and adjust focusing (accommodation muscles) are constantly working really hard to help them see normally. A good way to track the development of hyperopia is by taking frequent vision tests.
Most people with hyperopia do just fine once they receive prescription glasses. The prescription glasses used by people with hyperopia are convex, the opposite of the concave lenses used by people with myopia. The convex lenses make images travel a little longer before hitting the back of the eye (the retina), which helps compensate for any of the physical problems that cause hyperopia. Although hyperopia is not a fatal or directly dangerous condition, children with hyperopia should be given glasses as soon as their far-sightedness is discovered, because not being able to see fine details while their eyes are developing might prevent them from ever being able to see them. Hyperopia in children can also sometimes turn into "lazy eye" and other related problems, which might result in the need for the child to wear an eye patch over the dominant eye until the nerve signals return to normal in the "lazy" eye.
The vast majority of people with hyperopia live full, normal lives, with or without glasses, according to the severity of their far-sightedness. Most of the time people with far-sightedness can even get eye surgery (often done with a laser, see LASIK) to correct their vision back to a normal or almost-normal range. Because eyesight often changes as a person's eyes mature, everyone should have regular eye exams, but someone with hyperopia should pay special attention to any headaches or blurriness they get despite wearing their glasses. Their current prescription might be ineffective due to a gradual change in their eyesight, for better or worse. Most people who have hyperopia are also able to wear contact lenses, giving those who are far-sighted a wide variety of options for managing their vision problems.