A cataract is a clouding or opaque area over the lens of the eye - an area that is normally transparent. As this thickening occurs, it prevents light rays from passing through the lens and focusing on the retina - the light sensitive tissue lining located in the back of the eye. This clouding is caused when some of the protein which makes up the lens begins to clump together and interferes with vision.
In its early stages, a cataract may not cause a problem. The cloudiness may affect only a small part of the lens. However, the cataract may grow larger over time and affect more of the lens, making it harder to see. As less light reaches the retina, it becomes increasingly harder to see and vision may become dull and blurry. While cataracts cannot spread from one eye to another, many persons develop cataracts in both eyes.
Did You Know?
The word "cataract" literally means "waterfall." For persons with an advanced cataract that covers a large portion of the eye lens, vision can be described as trying to see through a waterfall.
Prior to Surgery:
You will see your primary care physician before surgery to make sure you are in good health. You will also visit the Ophthalmology Department for measurements to calculate the power of the artificial lens. At this appointment, you will be able to ask any questions that you have regarding cataract surgery and care after surgery.
Intraocular Lens Measurement
Usually, the method used to calculate the power of the artificial lens (intraocular lens) is very accurate. However, final results may vary for patients who are highly nearsighted, highly farsighted, or have had refractive surgery. If your vision after surgery is considerably different than what was planned based on your measurements, surgical replacement of the artificial lens might be considered in an attempt to improve the situation.
Before cataract surgery, you will receive a prescription for antibiotic eye drops. You will need to start using these drops the day before your surgery to help prevent infection in your eye. Your primary care physician will also review your other medications. You may need to stop taking blood thinners and other medications prior to cataract surgery.
After surgery, you will be sent home wearing a clear eye shield that should be used when napping or sleeping. You will need to wear this shield for at least one week. You will also be prescribed eye drops to use during your immediate recovery.
Your surgeon will examine you the day after your surgery. After this initial appointment, other appointments will be scheduled to check your healing. During recovery, you may resume reasonable activities; avoid strenuous bending or heavy lifting. After one week, you should be able to resume your normal activities and stop using the eye shield.
Cataracts occur as a result of aging, trauma, inflammation, or inherited characteristics. There could be several possible causes including:
- excessive exposure to sunlight
- steroid use
- diuretic use
- certain major tranquilizers
For several of the potential causes listed (i.e., steroids, diuretics, and/or major tranquilizers), additional research is needed to differentiate the effect of the disease from the effect of the drugs themselves.
How are cataracts diagnosed?
In addition to a complete medical history and eye examination, diagnostic procedures for cataracts may include:
- visual acuity test - the common eye chart test (see above), which measures vision ability at various distances.
- pupil dilation - the pupil is widened with eye drops to allow a close-up examination of the eye's retina.
In addition, other tests may also be performed to help your eye care professional learn more about the health and structure of your eye.
Possible risk factors for cataracts include:
Probably the greatest risk factor for cataracts is age. And, although age-related cataracts may develop between 40 and 50 years old, vision is usually not affected greatly until after age 60.
Recent studies have shown that people who live in high altitudes are more at risk for developing a cataract(s).
Excessive sun exposure
Person who spend more time in the sun may develop cataracts earlier than others. The American Academy of Ophthalmology now recommends wearing sunglasses and a wide brimmed hat to lessen exposure to ultraviolet rays.
Signs & Symptoms
The following are the most common symptoms of cataracts. However, each individual may experience symptoms differently. Symptoms may include:
- cloudy or blurry vision
- lights appear too bright and/or present a glare or a surrounding halo
- poor night vision
- multiple vision
- colors seem faded
- increased nearsightedness - increasing the need to change eyeglass prescriptions
- distortion of vision in either eye
Often in the disease's early stages, you may not notice any changes in your vision. Since cataracts tend to grow slowly, your vision will worsen gradually. Certain cataracts can also cause a temporary improvement in close-up vision, but this is likely to worsen as the cataract grows. The symptoms of cataracts may resemble other eye conditions. Consult a physician for diagnosis.
Specific treatment for cataracts will be determined by your physician based on:
- your age, overall health, and medical history
- extent of the disease
- expectations for the course of the disease
- your opinion or preference
- your tolerance for specific medications, procedures, or therapies
In its early stages, vision loss caused by a cataract may be aided with the use of different eyeglasses, a magnifying glass, or stronger lighting. When these measures are no longer helpful, surgery is the only effective treatment available, for most individuals. It is important to note that a cataract only needs to be removed when vision loss interferes with everyday activities such as driving, reading, or watching television. You and your doctor can make that decision together.
According to the National Eye Institute, part of the National Institutes of Health, cataract types are subdivided accordingly:
The majority of cataracts are related to aging.
Some babies are born with cataracts or develop them in childhood, often in both eyes. Some congenital cataracts do not affect vision, but others do and need to be removed.
Secondary cataracts develop primarily as a result of another disease occurrence in the body (i.e., diabetes). Secondary cataract development has also been linked to steroid use.
Eye(s) that have sustained an injury may develop a traumatic cataract either immediately following the incident, or several years later.
Other sources, including the American Academy of Ophthalmology, describe the different types of cataracts according to the cataract location on the eye lens, including:
- Nuclear cataract
- Cortical cataract
- Subcapsular cataract
This is the most common type of cataract, and the most common type associated with aging. Nuclear cataracts develop in the center of the lens and can induce myopia, or nearsightedness - a temporary improvement in reading vision which is sometimes referred to as "second sight." Unfortunately, "second sight" disappears as the cataract grows.
This type of cataract initially develops as wedge-shaped spokes in the cortex of the lens, with the spokes extending from the outside of the lens to the center. When these spokes reach the center of the lens they interfere with the transmission of light and cause glare and loss of contrast. This type of cataract is frequently developed in persons with diabetes, and while it usually develops slowly, it may impair both distance and near vision so significantly that surgery is often suggested at an early stage.
A subcapsular cataract usually starts as a small opacity under the capsule, at the back of the lens. This type of cataract develops slowly and significant symptoms may not occur until the cataract is well developed. A subcapsular cataract is often found in persons with diabetes, myopia, retinitis pigmentosa, and in those taking steroids.