Ocular terminology can be very confusing. When your optometrist diagnoses you or your family members with farsightedness, that’s usually the end of the explanation. Farsightedness can create so many different effects on your eyesight that it may seem like it’s not even a visual condition. Being farsighted (farsighted) usually results in good distance vision, with problems induced by near tasks such as reading and working with the computer. It is a somewhat confusing term since farsightedness is actually an optical error of distance vision, while the symptoms are more common when near vision is used.
To further complicate the situation, if your optometrist determines that your eye prescription is extremely farsighted, you will not see clearly up close or far away. If you are young and have a low to moderate degree of farsightedness, your vision may be clear at all distances. It’s no wonder people have a hard time understanding the concept of farsightedness and why ophthalmologists often avoid trying to explain it. Fortunately, there is a muscle called the ciliary muscle that surrounds the lens of the eye and is attached to the lens with small fibers. Active contraction of this muscle loosens the tension on the lens of the eye and increases the focusing power of the eyes. In lesser amounts of farsightedness if you are under forty, the eye’s focusing ability can adapt to farsightedness and clear your vision both far and near easily. Eye doctors use the words focus and accommodation interchangeably to indicate that the eye muscle has gone to work to increase the eye’s power for near vision.
Farsightedness in even lower amounts has been shown to interfere with reading in some children and adults, but typically within two to three prescription units it begins to create vision-related symptoms. Children and adolescents have a tremendous number of adaptations and sometimes very large prescriptions for farsightedness are not noticed because they can clarify near and far vision by focusing. They will often suffer from headaches and an unconscious aversion to reading due to eyestrain and the constant effort required to maintain clear vision. As we age, we gradually lose the ability to concentrate. This degradation of focus begins between the ages of fifteen and twenty, but affects distances so close to the beginning that we never notice because we don’t use our vision an inch or two away.
Farsighted people have a different type of problem than nearsighted people. They have to constantly focus to keep their distance vision clear, and as objects get closer, they have to further increase their focusing efforts. This isn’t a problem if you’re young and less farsighted, but as you get older or more farsighted, the extra effort you put in starts to show. This occurs initially with reading and computer use, due to the extra effort of concentrating on top of the amount required by distance. In high-tech areas like northern Colorado, there is a higher percentage of the population that uses computers all day and optometrists are seeing more symptoms of farsightedness. Hyperopic vision that is not corrected can be an important component of computer vision syndrome. Frequently, vision patients will be prescribed glasses or contact lenses for near work that only correct distance farsightedness. This reduces the amount of focus needed for near normal levels. The normal effort remaining to read or work on a computer rarely causes visual discomfort. This is another reason your optometrist may not tell you much about your farsightedness. It’s hard for them to explain why a prescription for distance glasses is recommended when you only have near problems.
As farsighted optometry patients enter their forties, they find that they have gradually begun to wear glasses all the time. Many people mistakenly believe that wearing glasses has weakened their eyes and sometimes feel that their ophthalmologist has made them dependent on glasses. This is an incorrect assumption, as the loss of accommodative ability would have occurred without wearing glasses and would have been a problem at a younger age in the absence of corrective glasses. This loss of focusing power is a visual condition specified as presbyopia, which patients often mistake for hyperopia. Although it progresses from a young age as explained above, it is only diagnosed when you reduce your ability to focus so that you cannot see at about sixteen inches, the average reading distance.
Optically, the farsighted eye is often too short and light is focused behind it rather than on the retina for distance. There may also be individual components of the eye that are too weak to focus vision properly. The lens might be underpowered, or the clear corneal tissue at the front of the eye might be slightly less curved than normal. A lens with positive or positive power is used to correct farsightedness. This is a lens that is thicker in the middle and thinner at the edges, like a biconvex lens. The best optical design for clear central and peripheral vision is a lens that is more curved at the front and still curved forward at the back, just to a lesser degree. This results in a lens with a center that is relatively far from the front of the eye, giving it a bulging appearance.
As you move an ophthalmic lens used for farsightedness away from the eye, the eye appears larger, much like the effect of moving a magnifying glass away from an object. This also increases the size of the image seen by the eye. Advanced optical designs have eliminated the resulting type of bug-eye appearance through the use of aspherical lens designs. Aspherical lenses start with a spherical front lens surface in the center (like the curve of a tennis ball), then the curvature gradually decreases or flattens out towards the edge of the lens. This is the traditional design that has an accompanying spherical curvature on the rear surface of the lens. Emerging new free-form lens technology allows aspherical lens curves to be rectified on the back surface of a lens. These lenses are very sophisticated designs that use different degrees of asphericity at different tangential lines to compensate for astigmatism in your prescription.
Either way, the flattened lens design allows the lenses to sit closer to your eyes, reducing magnification or bug-eye. The aspheric design because of the complex quirks of optics also counteracts various forms of optical aberrations (blurred vision) that normally occur when you look down the side of a spherical lens using a flatter lens design. A common misconception is that aspheric lenses improve vision. They do not significantly improve vision, but they do allow for thinner, lighter, and more cosmetically appealing lenses with less magnification. The aspherical design allows these improvements to be achieved without compromising clear peripheral vision. The lenses available to your ophthalmologist have undergone quantum advances in the last five years, probably equivalent to all the advances made in the previous fifty years. Improvements in lens design are beginning to resemble computer chips that double in capacity every eighteen months. The future of glasses has never been so bright!
Some facts about the hyperopic eye:
- Some people are farsighted in one eye and nearsighted in the other. If the amounts are correct, they can see near and far without bifocals.
- President James Buchannan was farsighted in one eye and nearsighted in the other (and had a twitch in his eye).
- President Harry Truman was clairvoyant.
- Latent farsightedness occurs when a child has compensated for it by steadily focusing into the distance for so long that they cannot relax their eyes to get a true reading of the prescription. Only checking the eyeglass prescription after special eye drops have removed the eyes’ focusing ability can produce an accurate prescription reading.
- The Ohio State University has launched a study to see if providing prescriptions that are not strong enough for babies with extreme farsightedness will help their eyes correct themselves.
- The eyes tend to become a little more farsighted (or less nearsighted) between the ages of forty and fifty.
- Young or middle-aged men can develop fluid swelling in the central retina and become hyperopic as a direct result of stress.
- Farsighted children tend to have farsighted brothers and sisters, but not necessarily parents with the eye condition.
- About one in four people is farsighted, but the number is slowly declining as the prevalence of nearsightedness increases.
Contact lenses can be very helpful in correcting farsightedness for a number of reasons. Unlike glasses that tilt away from the eye, contact lenses sit right on the surface of the eye and therefore provide very little magnifying effect. When you wear contact lenses, you are always looking through the optical center of the lens, which is the maximized point for good vision. This is due to the fact that contact lenses move with your eye when you look sideways. With glasses, you see through the lens at an angle when you turn your eyes, and this creates optical aberrations that degrade your vision. These benefits often result in contact lenses being the primary choice for corrective eyewear for higher levels of farsightedness in children and adolescents. This is often an age when your appearance is extremely important to your self-esteem. Who doesn’t want to look their best, especially when the old alternative was bug-eye magnifying glasses that weighed a ton and kept slipping down your nose constantly?
Eye exams are valuable in detecting eye prescription problems, but farsightedness is often missed because children have a great ability to concentrate and pass the 20/20 test. Only a comprehensive eye exam by your ophthalmologist can ensure your children and teens have the correct eye prescription for effective reading and learning in school. Schedule an annual eye exam today. And don’t forget the new options you have as a farsighted adult.