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Cataracts

1. Definition

2. Causes

3. Types

4. Relevant anatomy, physiology, biochemistry

5. Symptoms and signs

6. Medical emergencies associated with this medical condition

7. Risk factors

8. Normal values

9. Various diagnostic tests

10. Diagnosis

11. Complications

12. Treatment or management

13. Epidemiology

14. History of this medical condition

15. Prevention

What are the symptoms of cataracts?
What are the different types of cataracts?
What can one expect during cataract surgery?
Are lasers used during cataract surgery?
Cataract specialists at Bascom Palmer
Other Cataract Resources

What are cataracts?

"Cataract" is the name used to describe a condition wherein the lens of the eye becomes opacified or cloudy blocking some light from reaching the retina and interfering with vision. Cataracts are multi-faceted. We don't know all the causes, but we do know that time, aging, and hereditary factors all play a role in cataract development. Cataract formation can be accelerated by trauma, diabetes, sunlight, and certain medications. Typically, cataracts occur in adults ("adult onset"), but may occur as a congenital disorder. More than half of all Americans age 65 and older have a cataract.

What are the symptoms of cataracts?

Early signs of cataracts include blurred or cloudy vision; frequent changes in eyeglass or contact lens prescriptions; night glare and hazy vision; and colors that seem to fade. An ophthalmologist must determine if these symptoms are really caused by a cataract or by some other eye problem that may need treatment.

For an adult, a cataract should be removed only when it interferes with lifestyle and makes it difficult to continue normally enjoyable activities. Generally, there is no such thing as a cataract being "ripe" or "not ripe" for removal. What matters is whether or not the problem interferes with vision. In rare instances, a "hyper-mature" cataract may cause elevated eye pressure or inflammation of the eye. In this case, it must be removed immediately. Otherwise, removal of a cataract is at the patient's discretion.

What are the different types of cataracts?

* Age-related cataract: Most cataracts are related to aging.
* Congenital cataract: Some babies are born with cataracts or develop them in childhood, often in both eyes. These cataracts may not affect vision. If they do, they may need to be removed.
* Secondary cataract: Cataracts are more likely to develop in people who have certain other health problems, such as diabetes. Also, cataracts are sometimes linked to steroid use.
* Traumatic cataract: Cataracts can develop soon after an eye injury, or years later.

What can one expect during cataract surgery?

Cataract surgery is the most frequently performed surgery in the United States - and the most successful. Over 95 percent of those who have cataract surgery regain vision levels between 20/40 and 20/20.

Cataract surgery usually lasts less than one hour and is almost painless. Many people choose to stay awake during surgery and have an anesthetic to numb the nerves in and around the eye.

A lens implant (intraocular lens) inserted during cataract surgery gives the surgeon an opportunity to correct nearsightedness or farsightedness. Current research on intraocular lens implants also may provide high quality correction for astigmatism and for both bifocal and multi-focal vision. Bifocal implants are currently used, but physicians have yet to achieve consistently satisfactory outcomes.

The time required for recuperation after cataract removal depends on the type of procedure performed and the patient's individual rate of healing. The decision as to which procedure is best for an individual's eye is made by the patient's ophthalmologist.

One technique ophthalmologists use is phacoemulsification. This procedure involves making a tiny incision, about 2.5 to 3.5 millimeters in length. A pencil-like instrument, inserted through the opening, is used to emulsify (breakdown into tiny pieces) and aspirate the clouded lens material. Then the intraocular lens is inserted into place.

Other techniques include:

* Phacofracture cataract surgery - the lens is removed through a small incision by "fracturing" it into several small segments

* Extracapsular cataract surgery - the lens is removed in one piece through a larger incision

* Intracapsular surgery - the lens and capsule are completely removed, a rarely used procedure

In some cases after cataract surgery, a haziness develops in the membrane or capsule supporting the intraocular lens implant. When this happens, a laser is sometimes used to create a small opening in the membrane (a capsulotomy) through which the patient can see clearly. Lasers are used because they are able to make a small, very precise opening.

Are lasers used during cataract surgery?

During the past three decades, the techniques and results of cataract surgery in the U.S. have changed dramatically:

* Ophthalmologists have moved from intracapsular cataract extraction as the preferred method to almost exclusive use of extracapsular techniques.

* Smaller incisions have become the standard: Ultrasonic (U/S) phacoemulsification is now the method of choice for most surgeons.

* Improved surgical techniques for removing the anterior lens capsule have decreased the incidence of both intraoperative (during surgery) and postoperative capsular complications.

* Along with these advances have come improved intraocular lens materials and designs, which are especially well suited for use with smaller incisions.

* Improved wound construction allows many wounds to be left unsutured.

* Smaller wounds require shorter recovery time and allow greater intraoperative control and safety.

Despite these advances, however, U/S phacoemulsification techniques are not without potential sight-threatening complications.

Possible complications related to U/S phacoemulsification include corneal or scleral burn, iris trauma, rupture of the posterior capsule, loss of vitreous fluid, cystoid macular edema, and induced astigmatism. These complications may lead to compromised vision prompting investigations into newer techniques of using laser energy to remove cataracts.

The advantages of using a laser to remove cataracts include the ability to use fiber optics with a smaller diameter than typical ultrasonic probes; and direct energy precisely on target tissue by means of a smooth, blunt, stationary probe.

Theoretically, the use of a laser, compared with U/S phacoemulsification:

* reduces heat and vibration in the wound and in the eye
* decreases the chance of capsular rupture
* requires smaller incisions
* allows faster recovery