Nearsightedness

Introduction

Nearsightedness (myopia) is a common vision condition in which you can see objects near to you clearly, but objects farther away are blurry.

The degree of your nearsightedness determines your focusing ability. People with severe nearsightedness can see clearly only objects just a few inches away, while those with mild nearsightedness may clearly see objects several yards away.

Nearsightedness may develop gradually or rapidly, often worsening during childhood and adolescence. Nearsightedness tends to run in families.

A basic eye exam can confirm nearsightedness. You can easily correct the condition with eyeglasses or contact lenses. Another treatment option for nearsightedness is surgery.

Signs and symptoms

Being nearsighted may mean:

• Distant objects appear blurry
• You need to squint to see clearly
• You have headaches caused by excessive eyestrain

Nearsightedness is often first detected during childhood, from early school years through the later teens. A child with nearsightedness may:

• Persistently squint
• Sit very close to the television, movie screen or chalkboard
• Hold books very close while reading
• Seem to be unaware of distant objects

Causes

CLICK TO ENLARGE

	Anatomy of the eye
	Nearsightedness (myopia)

Your eye has two parts that focus images:

• The cornea, the clear front surface of your eye
• The lens, a clear structure inside your eye that changes shape to help focus objects

In a perfectly shaped eye, each of these focusing elements has a perfectly smooth curvature like the surface of a rubber ball. A cornea and lens with such curvature bend (refract) all incoming light in such a way as to make a sharply focused image on the retina, at the back of your eye.

A refractive error
However, if your cornea or lens isn’t evenly and smoothly curved, light rays aren’t refracted properly, and you have a refractive error. Nearsightedness is one type of refractive error. Nearsightedness can occur when your cornea is curved too much or when your eye is longer than normal. Instead of being focused precisely on your retina, light is focused in front of your retina, resulting in a blurry appearance for distant objects.

Other refractive errors
In addition to nearsightedness, other refractive errors include:

• Farsightedness (hyperopia). This occurs when your cornea is curved too little or your eye is shorter from front to back than normal. The effect is the opposite of nearsightedness. Light is focused beyond the back of your eye, making nearby objects blurry. You’re usually able to see faraway objects clearly.
• Astigmatism. This occurs when your cornea is curved more steeply in one direction than in another. Uncorrected astigmatism blurs your vision. Typically, the images you see will be blurred more in one direction than another. For example, horizontal images may be more out of focus than are vertical or diagonal images.

When to seek medical advice

If your degree of nearsightedness is pronounced enough that you can’t perform a task as well as you wish, or if your quality of vision detracts from your enjoyment of activities, see an eye doctor. He or she can determine the degree of your nearsightedness and advise you of your options to correct your vision.

Screening and diagnosis

Nearsightedness is diagnosed by a basic eye exam. Three kinds of eye specialists, each with different training and experience, can provide routine eye care:

• Ophthalmologists. An ophthalmologist is an eye specialist with a doctor of medicine (M.D.) degree who provides full eye care, including performing complete eye evaluations, prescribing corrective lenses, diagnosing and treating common and complex eye disorders, and performing eye surgery when it’s necessary.
• Optometrists. An optometrist has a doctor of optometry (O.D.) degree. Optometrists are trained to evaluate vision, prescribe corrective lenses and diagnose common eye disorders. Complicated eye conditions, including those requiring surgery, must be treated by an ophthalmologist.
• Opticians. An optician is an eye specialist who fills prescriptions for eyeglasses — assembling, fitting and selling them. In some states, opticians are also allowed to sell and fit contact lenses.

A complete eye examination involves a series of tests. Your eye doctor may use odd-looking instruments, aim bright lights directly at your eyes and request that you look through an array of lenses. Each test allows your doctor to examine a different aspect of your vision.

According to the American Academy of Ophthalmology, recommendations for regular eye exams include:

Adults
If you don’t wear glasses or contacts, have no symptoms of eye trouble and are at a low risk of developing eye disease, it’s recommended that you have an eye exam at the following intervals.

• At least once between ages 20 and 39
• Every three to five years between the ages of 20 and 29 if you’re at high risk of certain eye diseases, such as glaucoma
• Every two to four years between ages 40 and 64
• Every one to two years beginning at age 65

However, if you wear glasses or contacts, have your eyes checked every year. And if you notice any problems with your vision, schedule an appointment with your eye doctor as soon as possible, even if you’ve recently had an eye exam. Blurred vision, for example, may suggest you need a prescription change.

Children and adolescents
Children need to be screened for eye disease and have their vision tested by a pediatrician, an ophthalmologist or another trained screener at the following ages and intervals.

• Between birth and 3 months
• Between 6 months and 1 year
• Around 3 years
• Around 5 years

Additionally, it’s recommended that school-aged children be screened at school or through community programs approximately every two years to check for vision problems.

Your child or adolescent may need more frequent visits if he or she experiences any problems with vision or has symptoms of eye trouble. In addition, children and adolescents who have a disease that puts their eyes at risk, such as diabetes, may need more frequent eye exams.

Complications

Nearsightedness may be associated with several complications, such as:

• Reduced quality of life. Uncorrected nearsightedness can affect your quality of life. You might not be able to perform a task as well as you wish, and your limited vision may detract from your enjoyment of day-to-day activities.
• Eyestrain. Squinting to see in the distance can cause eyestrain and headaches.
• Impaired safety. For your own safety and that of others, don’t drive or operate heavy equipment if you have an uncorrected vision problem.
• Glaucoma. Severe nearsightedness increases your risk of developing glaucoma, a potentially serious eye disease.
• Retinal tear and detachment. If you’re significantly nearsighted, it’s possible that the retina of your eye is thin. The thinner your retina, the higher your risk of developing a retinal tear or retinal detachment. If you experience a sudden onset of flashes, floaters or a dark curtain or shadow across part of your eye, seek medical assistance immediately. Retinal detachment is a medical emergency, and time is critical. Unless the detached retina is promptly surgically reattached, this condition can cause permanent loss of vision in the affected eye.

Treatment

The goal of treating nearsightedness is to help focus light on your retina through the use of corrective lenses or refractive surgery.

Corrective lenses
Wearing corrective lenses treats nearsightedness by counteracting the increased curvature of your cornea or the increased length of your eye. Types of corrective lenses include:

• Eyeglasses. Also called spectacles, eyeglasses come in a wide variety of styles and are easy to use. Eyeglasses can correct a number of vision problems at once, such as myopia and astigmatism. Eyeglasses may be the most economical correction alternative.
• Contact lenses. A wide variety of contact lenses are available — hard, soft, extended wear, disposable, rigid gas permeable (RGP) and bifocal. Ask your eye doctor about their pros and cons and what might be best for you.

Refractive surgery
This treatment corrects nearsightedness by reshaping the curvature of your cornea. Refractive surgery methods include:

• Laser-assisted in-situ keratomileusis (LASIK). LASIK is a procedure in which an ophthalmologist uses an instrument called a keratome or a special laser called a femtosecond laser to make a thin, circular hinged cut into your cornea. Your eye surgeon then uses a different type of laser, called an excimer laser, to remove layers from the center of your cornea to flatten its domed shape.
• Laser-assisted subepithelial keratomileusis (LASEK). Instead of creating a flap in the cornea, the surgeon creates a flap only in the cornea’s thin protective cover (epithelium). Your surgeon will use an excimer laser to reshape the cornea’s outer layers and flatten its curvature and then reposition the epithelial flap. To encourage healing, a bandage contact lens is worn for several days after this procedure.
• Photorefractive keratectomy (PRK). This procedure is similar to LASEK, except the surgeon removes the epithelium. It will grow back naturally, conforming to your cornea’s new shape. Like LASEK, PRK requires the use of a bandage contact lens following the procedure.
• Anterior chamber intraocular lens (IOL) implant. These lenses are surgically implanted into the eye, in front of the eye’s natural lens. They may be an option for people with moderate to severe myopia, although their use is controversial and they aren’t widely used.

All eye surgeries have some degree of risk, and possible complications from these eye procedures include infection, corneal scarring, vision loss and visual aberrations, such as seeing halos around lights at night. Discuss the potential risks with your doctor.

Prevention

Although a number of scientific attempts have been made to halt or slow the progression of nearsightedness, there are no proven ways to prevent the condition from occurring or progressing.

Self-care

Although you can’t prevent nearsightedness, you can help protect your eyes and your vision. Follow these steps:

• Have your eyes checked. Regardless of how well you see, have your eyes checked regularly for problems.
• Control chronic health conditions. Certain conditions, such as diabetes and high blood pressure, can affect your vision if you don’t receive proper treatment.
• Recognize symptoms. Sudden loss of vision in one eye, sudden hazy or blurred vision, flashes of light, black spots, or halos or rainbows around lights may signal a serious eye problem, such as retinal tear or detachment, requiring urgent medical attention. Similar symptoms can be caused by other serious medical problems, such as acute glaucoma or a stroke. Talk to your doctor immediately if you experience any of these symptoms.
• Protect your eyes from the sun. Wear sunglasses that block ultraviolet (UV) radiation. This is especially important if you spend long hours in the sun or are taking a prescription medication that increases your sensitivity to UV radiation.
• Eat healthy foods. Maintain a healthy diet that includes plenty of fruits and vegetables, which have shown to enhance eye health. Try foods that contain vitamin A and beta carotene, such as carrots, yams and cantaloupe.
• Don’t smoke. Just as smoking isn’t good for the rest of your body, it can affect your eye health as well.
• Use the right glasses. The right glasses optimize your vision. Having regular exams will ensure that your eyeglass prescription is correct.
• Use good lighting. Use adequate light for optimal vision.

Powered by MightyAdsense