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Cataracts

Cataracts are cloudy areas in the eye's lens causing blurred or hazy vision. Some cataracts stay small and don't change your eyesight a lot. Others become large and reduce vision.

PubMed Health Glossary
(Source: NIH - National Institute on Aging)

About Cataracts

A cataract is a clouding of the lens in the eye that affects vision. Most cataracts are related to aging. Cataracts are very common in older people. By age 80, more than half of all Americans 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.

What is the lens?

The lens is a clear part of the eye that helps to focus light, or an image, on the retina. The retina is the light-sensitive tissue at the back of the eye.

In a normal eye, light passes through the transparent lens to the retina. Once it reaches the retina, light is changed into nerve signals that are sent to the brain.

The lens must be clear for the retina to receive a sharp image. If the lens is cloudy from a cataract, the image you see will be blurred.

Are there other types of cataracts?

Yes. Although most cataracts are related to aging, there are other types of cataract:...Read more about Cataracts NIH - National Eye Institute

What works? Research summarized

Evidence reviews

Using medications (antimetabolites) to avoid scarring after cataract surgery, which might cause failure of a previous glaucoma operation

Review question: We reviewed the evidence on the effect of using medications (antimetabolites) to avoid scarring after cataract surgery, which might cause failure of a previous glaucoma operation. We did not find any trials to include in this review.

Non‐steroidal anti‐inflammatory drugs for treating fluid accumulation in the macula after cataract surgery

Cystoid macular oedema (CMO) is the accumulation of fluid in the macula (central retina) due to leakage from capillaries. Clinically significant CMO following cataract surgery is a complication of unknown cause. Acute CMO, defined as oedema of less than four months duration, often gets better spontaneously. This review included seven randomised controlled trials with a total of 266 participants. Four trials studied the effects of non‐steroidal anti‐inflammatory agents (NSAIDs) in chronic CMO while the other three examined the effect of NSAIDs in acute CMO. This review found two trials which showed that topical NSAID (0.5% ketorolac tromethamine ophthalmic solution) has a positive effect on chronic CMO and a third trial which was supportive of this finding (albeit not statistically significantly so). One study suggested no effect and our review suggests further work is needed for a more conclusive decision regarding use of NSAIDS in chronic CMO. Similarly, the effects of NSAIDs in acute CMO remain unclear and this too needs further investigation.

Antioxidant vitamins for preventing and slowing the progression of age‐related cataract

A cataract occurs when the normally clear lens in the eye becomes cloudy. Cataracts are the leading cause of correctable reduced vision worldwide. Most cataracts develop slowly with normal aging. However, cataracts also may be related to genetic diseases and medical conditions such as diabetes. Other factors such as poor nutrition, sun damage, radiation, corticosteroids, smoking, alcohol, eye trauma or other eye surgery may influence cataract formation.

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Summaries for consumers

Cataracts: Cataract surgery

A cataract is an eye condition where the lens of the eye gradually becomes cloudy – usually as part of the natural aging process. The only effective treatment is surgery. Cataract surgery involves removing the cloudy lens and replacing it with an artificial one. Cataracts cause vision loss. Your eyesight becomes increasingly dull and blurry, as if you were looking at things through a veil or fog. You might be more sensitive to bright lights too. If cataracts are left untreated, they can – but do not always – lead to blindness. Some people’s vision is only slightly affected, whereas others might lose their eyesight very quickly. Surgery involves removing the cloudy lens and replacing it with an artificial lens. It is one of the most common surgical procedures performed in Germany, where about 800,000 people have cataract surgery every year.

Using medications (antimetabolites) to avoid scarring after cataract surgery, which might cause failure of a previous glaucoma operation

Review question: We reviewed the evidence on the effect of using medications (antimetabolites) to avoid scarring after cataract surgery, which might cause failure of a previous glaucoma operation. We did not find any trials to include in this review.

Non‐steroidal anti‐inflammatory drugs for treating fluid accumulation in the macula after cataract surgery

Cystoid macular oedema (CMO) is the accumulation of fluid in the macula (central retina) due to leakage from capillaries. Clinically significant CMO following cataract surgery is a complication of unknown cause. Acute CMO, defined as oedema of less than four months duration, often gets better spontaneously. This review included seven randomised controlled trials with a total of 266 participants. Four trials studied the effects of non‐steroidal anti‐inflammatory agents (NSAIDs) in chronic CMO while the other three examined the effect of NSAIDs in acute CMO. This review found two trials which showed that topical NSAID (0.5% ketorolac tromethamine ophthalmic solution) has a positive effect on chronic CMO and a third trial which was supportive of this finding (albeit not statistically significantly so). One study suggested no effect and our review suggests further work is needed for a more conclusive decision regarding use of NSAIDS in chronic CMO. Similarly, the effects of NSAIDs in acute CMO remain unclear and this too needs further investigation.

See all (85)

Terms to know

Accommodative Lens
An accommodative intraocular lens implant has only one focal point, but it acts as if it is a multifocal IOL. Its design allows the focusing muscles to move it back and forth.
Bilateral
Affecting both the right and left sides of the body.
Intraocular Lens (IOL)
Artificial implanted lenses.
Lens in the Eye
A clear disk that focuses light, as in a camera or microscope. In the eye, the lens is a clear, curved structure at the front of the eye behind the pupil. It focuses light rays that enter the eye through the pupil, making an image on the retina (light-sensitive layers of nerve tissue at the back of the eye).
Monofocal Lens
Monofocal intraocular lenses provide vision at one distance only: far, intermediate, or near.
Multifocal Lens
Multifocal intraocular lenses allow the patient to visualize objects at more than one distance.
Ophthalmologist
A doctor who specializes in diagnosing and treating eye problems, including injury and disease.
Retina
The light-sensitive tissue lining at the back of the eye. The retina converts light into electrical impulses that are sent to the brain through the optic nerve.
Unilateral
Having to do with one side of the body.

More about Cataracts

Photo of an adult

Also called: Cataractous

Other terms to know: See all 9
Accommodative Lens, Bilateral, Intraocular Lens (IOL)

Related articles:
How the Eye Works

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