Cataracts

A cataract is a clouding of the crystalline lens inside the eye. This lens focuses light into the back of the eye. It is located behind the iris (the colored part of the eye) and pupil. The lens changes shape to focus on objects at different distances. The loss of the ability of the lens to change shape is what causes presbyopia, or the need for reading glasses over the age of forty.

The lens is clear so that light focuses clearly onto the retina. As the lens ages, the structure changes and it becomes more cloudy. Portions of the lens become white instead of being clear. These white or cloudy areas are what eye doctors call a cataract. Most cataracts develop very slowly and affect vision gradually. Many people can have the early stages of a cataract and still have normal vision.

There are many types of cataract depending on where they are in the lens:

A nuclear cataract is a cloudiness or yellowing of the center of the lens and is most often due to normal aging changes.
A cortical cataract is a white cataract in a spoke pattern which starts at the periphery of the lens. They often grow in towards the center of the lens which is when they start to affect vision. They are also due to normal aging changes but are commonly seen in diabetics.
A subcapsular cataract is a cloudiness of the back part of the lens. This type of cataract may cause vision changes very quickly because of its location. Subcapsular cataracts can occur naturally as a normal aging change but are often secondary to other ocular diseases like inflammation, retinitis pigmentosa and diabetic eye changes. They can also be caused by the long-term use of topical or oral steroids.

Cataract Symptoms

Most cataracts affect vision gradually over many years and often people don’t notice the changes until they become pronounced. Many people with cataracts will notice some degree of blurred vision, making it more difficult to read signs and see at distance. Sometimes, cataracts can cause something called “second sight” making it easier to read than before. However, this change is temporary. Many people with cataracts notice they need more light to do tasks like reading or sewing. Cataracts can also cause glare from lights, this is most noticeable when driving at night. Cataracts generally cause dim vision and cause colors to seem less bright.

What Causes a Cataract?

There is no consensus as to why cataracts occur as a normal part of aging for most people. The incidence of cataracts does increase as people age and most people over the age of seventy have some sort of cataract.

Most eye care practitioners believe that exposure to the sun (specifically ultraviolet light) increases the risk of developing cataracts and therefore recommend wearing sunglasses and hats.

Many diabetics develop cataracts at younger than normal ages, however, it has not been determined if this is due to the diabetes itself or the medications diabetics use to control their disease.

Some people have a family history of cataracts occurring at a young age, suggesting a genetic component to the development of cataracts.

Cataract Treatment

Most patients with cataracts do not need cataract surgery until the decrease in vision affects their ability to function in daily life. Often a change in their glasses prescription can help improve vision in the early stages of cataracts. As cataracts advance, changing the prescription does not improve vision and cataract surgery is usually recommended.

Cataract surgery is an outpatient procedure, enabling the patient to return to normal activities fairly quickly after the surgery. It is the most common surgery performed in the United States and results in better vision for most people. Most people have 20/20 to 20/40 vision after cataract surgery.

The cataract surgeon removes the cloudy lens and replaces it with a clear, plastic implant called an intraocular lens. The new intraocular lens sits in the same place as the old cloudy lens enabling the patient to see more clearly. After cataract surgery topical medications to help the eye heal and prevent infection are prescribed. One month after cataract surgery most people have healed completely and are ready for a new pair of glasses. A new glasses prescription is necessary because cataract surgery changes the prescription of the eye.

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