What is Hyperopia?
Hyperopia is the medical term for farsightedness. Farsighted individuals usually have difficulty seeing objects up close, but can see distant objects clearly. Tasks like reading, sewing, or typing can be difficult and can cause blurry vision or eye strain. People with high hyperopic prescriptions will have difficulty seeing objects up close as well as far away. Most children are born with some degree of hyperopia, but this typically corrects itself by around five years of age. Farsightedness affects approximately 5–10 percent of the US adult population. Several factors contribute to farsightedness, such as the shape of the cornea, the placement and shape of the lens, and the length of the eyeball. Normally, images are clearly and directly focused on the retina. With hyperopia, the focal point of the image is behind the retina, so a blurry image is sent to the brain.
People with hyperopia tend to have eyestrain, poor focusing control, spasms of focus, headaches, trouble reading, and eye fatigue. Children with high hyperopia may display crossed eyes (a condition known as strabismus). A child’s behavior may signal that they are having trouble with their vision. Farsighted children sometimes display a lack of interest in school, especially in reading. Children who have vision problems may also squint and rub their eyes often. People who are highly farsighted may experience blurry vision when looking at objects near and far.
Hyperopia is easily treated with corrective glasses or contact lenses. Hyperopia may be a risk factor for a lazy eye in children with high hyperopic prescriptions. Hyperopic eyes, due to their compact shape, may also be more prone to narrow-angle glaucoma. Children with hyperopia may develop problems in school, such as difficulty reading books and chalkboards, which can lead to a lack of interest in learning.
Causes of Hyperopia
Hyperopia typically occurs because the eyeball is shorter than normal or the shape of the cornea is too flat. This causes the image to focus behind the retina rather than on it. In some cases the lenses of the eye may not converge properly due to weakness of the ciliary muscles, which are responsible for changing focus to adjust for variation in distance (a process known as accommodation).
Risk Factors for Hyperopia
The biggest risk factor for hyperopia is genetics. If you have a farsighted family member, chances are you and other relatives will develop the same refractive error as you age. Age plays another role in hyperopia.
Farsightedness is measured in units called diopters. A diopter is the measure of the power of the eyeglasses lens, determined by the distance from the lens surface at which light is brought into perfect focus. On an eyeglass prescription, a plus sign indicates a prescription for farsightedness, which is followed by numbers indicating the degree of hyperopia.
- +0.25 to +1.00 diopters = mild farsightedness
- +1.25 to +4.00 diopters = moderate farsightedness
- +4.25 to +8.00 diopters = severe farsightedness
- +8.00 diopters or higher = extreme farsightedness
Some schools give students vision screenings, but not all of them test for farsightedness. If you or a family member has hyperopia, you should consider taking your child in to see an optometrist or ophthalmologist for a complete eye exam. Annual exams are recommended. To diagnose hyperopia, an eye doctor will perform a visual acuity test as well as a refraction test to determine the amount of correction needed in eyeglasses or contact lenses.
Treatment for Hyperopia
Glasses are prescribed for patients with farsightedness. This corrects for the refractive error, allowing the individual to see well. Like treatments for myopia, treatments for hyperopia are designed to refract or bend light so that it focuses on the retina of each eye, either through corrective lenses or by reshaping the cornea. At a young age, depending on the degree of hyperopia, eyeglasses or contacts are usually the first option. Refractive LASIK Eye Surgery is a popular treatment that eliminates the need for contacts or eyeglasses. Refractive eye surgery is usually not performed until the patient’s eyes have finished growing, which happens around the age of 21. Phakic Intraocular Lenses can be used to correct severe hyperopia. This treatment implants a lens much like a contact lens inside the eye to allow better light refraction. Advancements in Lens Replacement Surgery with technology such as Crystalens or ReSTOR intraocular lenses offer a promising option for patients with hyperopia and don’t want to depend on reading glasses or bifocals after the surgery.
Prognosis for Hyperopia
With proper treatment, vision can be corrected and symptoms reduced.
Farsighted individuals who have flat corneas or short eyeballs cannot prevent hyperopia from developing. Reducing your visual demand may improve symptoms. Modifications to reduce your visual demand include improving lighting or reducing glare, using better quality printed material, and keeping reading material 14–16 inches away from your eyes.