Causes

The following conditions can cause blurry vision to develop slowly:

Nearsightedness (myopia) is difficulty in seeing objects that are far away. Objects close up are seen clearly. People who are nearsighted may hold reading material just a few inches from their noses.

Farsightedness (hyperopia) causes nearby objects to appear fuzzy. Objects at a distance are seen clearly. People who are farsighted often hold their reading material at arm’s length.

Astigmatism can cause areas of blurry vision because the cornea of your eye is not perfectly spherical (circular) as it should be. People with astigmatism may find it hard to see vertical, horizontal, or diagonal lines clearly. Astigmatism can be accompanied by nearsightedness or farsightedness.

Presbyopia is a problem of aging. As you get older, the eye lens hardens and loses its flexibility, making it hard to focus on nearby objects. Eyeglasses with bifocal lenses can correct most cases of presbyopia.

Cataracts cloud the lens of the eye, impairing vision. They usually take several years to develop. Most cataracts are a result of aging, but they can also be caused by injuries, birth defects, too much heat or ultraviolet light, medications, and diabetes. Lenses affected by cataracts can be replaced by surgery if necessary.

Glaucoma, a major cause of blindness, is increased pressure within the eyeball. This pressure can damage the optic nerve, which controls sight. Symptoms of glaucoma include loss of vision to each side (peripheral vision), halos around lights, eye pain, blurred vision, and gradual loss of sight. Glaucoma destroys peripheral vision first, so it often is not caught until a good deal of vision is lost. Early diagnosis through routine glaucoma checks after age 40 is the key to treating this problem.

Macular degeneration causes increasingly blurred central vision and most often strikes elderly people. Reduced or distorted vision caused by macular degeneration is most noticeable when you read. If diagnosed early, laser treatment can sometimes keep it from getting worse.

Vision Changes That Can Signal a Stroke

Most vision problems develop gradually. If any of the following symptoms occur suddenly, they may be signs of a stroke.

• Sudden loss of sight, especially in one eye
• Loss of part of your visual field
• Double vision
• Vision changes with paralysis or weakness

Treatment for Refractive Errors

Refractive errors include nearsightedness, farsightedness, presbyopia, and astigmatism. There are many different treatments available, and what’s best for you depends on your eyes and your lifestyle. 

Corrective lenses
Eyeglasses correct refractive errors by adding or subtracting focusing power to the cornea and lens. They are a good vision correction option for people who can’t wear contact lenses or who aren’t candidates for laser surgery.

Contact lenses continue to undergo advances that make them a good option for more and more people. They are available in soft or hard plastic, disposable, bifocal, tinted—and with many other available features.

Corneal refractive therapy
Corneal refractive therapy, or orthokeratology, is a fairly new treatment to improve nearsightedness. This treatment uses a series of hard contact lenses—which can be worn during the day or while you sleep—to gradually flatten the cornea, improving its ability to refract light and focus. Vision improvement is temporary. After the use of lenses is discontinued, the cornea returns to its original shape, and nearsightedness returns.

Surgery
The shape of your cornea is what determines whether you are nearsighted, farsighted, or have astigmatism. LASIK surgery is a relatively new procedure that can be used to correct these vision problems. The term LASIK is short for laser in-situ keratomileusis, which is a special type of laser surgery. In this procedure, a thick layer of the cornea is folded back using a special instrument. The exposed cornea is then reshaped with a laser, and the corneal flap is returned to its original position. No stitches are needed.

LASIK surgery is performed as an outpatient procedure. Most people recover in a couple of days, and the need for glasses or contacts is reduced or eliminated.

Prevention

• Have regular eye exams—every 3 to 5 years if you don’t have vision problems, every 2 years if you wear eyeglasses or have other vision problems. Your doctor or eye specialist may recommend more frequent exams, especially if you wear contact lenses.
• Wear safety glasses or goggles whenever you use power tools, lawnmowers, or other devices that could cause objects to fly toward your eyes.
• Wear sunglasses with UV protection when you are out in bright sunlight. Be especially careful when sunlight is reflected by water or snow. Too much UV light has been linked to cataracts.
• Don’t smoke. It can put you at higher risk for macular degeneration and other eye problems.
• If you have diabetes or high blood pressure, keep it under control. Both conditions are risk factors for macular degeneration, glaucoma, and other eye problems.