Astigmatism

A common imperfection in the eye's curvature.

With astigmatism, the front surface of the eye or the lens, inside the eye, is curved differently in one direction than the other much like the shape of a rugby ball. A common symptom is blurry vision or shadows arounds objects and letters.

Treatments include prescription eyeglasses or contact lenses. Laser-assisted surgery, such as LASIK, also may help.

Cataract

A cataract is a clouding of the eye's natural lens, which lies behind the iris and the pupil.  Most cataracts are related to aging but can also occur due to injury or disease. For people who have cataracts, seeing through cloudy lenses is a bit like looking through a frosty or fogged-up window. Cataracts are very common in older people. By age 80, more than half of the population either have a cataract or have had cataract surgery. A cataract can occur in either or both eyes. It cannot spread from one eye to the other. If the cataract develops to the point that it affects your daily activities, surgery may be recommended.

Glaucoma

Glaucoma, also known as the “silent thief of sight”  is a condition that causes damage to your eye's optic nerve and gets worse over time. It's often linked to a buildup of pressure inside your eye. Glaucoma tends to be inherited and may not show up until later in life.

The increased pressure, called intraocular pressure, can damage the optic nerve, which transmits images to your brain. If the damage continues, glaucoma can lead to permanent vision loss. Without treatment, glaucoma can cause total permanent blindness within a few years.

Most people with glaucoma have no early symptoms or pain. You need to see your eye doctor regularly so she can diagnose and treat glaucoma before long-term visual loss happens.

If you’re over age 40 and have a family history of the disease, you should get a complete eye exam from an eye doctor every 1 to 2 years. If you have health problems like diabetes or a family history of glaucoma or are at risk for other eye diseases, you may need to go more often.

Hyperopia

Hyperopia, also known as farsightedness, is a common type of refractive error where distant objects may be seen more clearly than objects that are near. However, people experience hyperopia differently. Some people may not notice any problems with their vision, especially when they are young. For people with significant hyperopia, vision can be blurry for objects at any distance, near or far.

Myopia

Myopia is the medical term for nearsightedness. People with myopia see objects more clearly when they are close to the eye, while distant objects appear blurred or fuzzy. Reading and close-up work may be clear, but distance vision is blurry.

Presbyopia

Presbyopia (which literally means "aging eye") is an age-related eye condition that makes it more difficult to see very close. Most presbyopes describe blurred near vision when reading, sewing or working at the computer. When you are young, the lens in your eye is soft and flexible. The lens of the eye changes its shape easily, allowing you to focus on objects both close and far away.

Around age 40, the lens becomes more rigid. Because the lens can’t change shape as easily as it once did, it is more difficult to read at close range. You can't escape presbyopia, even if you've never had a vision problem before. Even people who are nearsighted will notice that their near vision blurs when they wear their usual eyeglasses or contact lenses to correct distance vision.