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Cataracts

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of cataracts.


Treatment

Although surgery is the only remedy for cataracts, it is almost never an emergency. Most cataracts cause no problem other than reducing a person's ability to see, so there is no harm in delaying surgery.

Early cataracts may be managed with the following measures:

It is important to note, however, that there are no treatments that will prevent cataract formation or progression or that make a cataract disappear.

Progression of Cataracts. Patients and their families usually have plenty of time to consider options carefully and discuss them with an ophthalmologist. There is no constant rate at which cataracts progress:

Choosing Cataract Surgery

Each year about 2.8 million cataract operations are performed, making it the most common operation in the U.S. for people over age 65. Cataract surgery may be the oldest procedure in the world, having been introduced to Europe from India by Alexander the Great's army.

In the past, cataract surgery was not performed until the cataract had become well developed. Newer techniques, however, have made it safer and even more efficient to operate in earlier stages. In fact, modern cataract techniques not only remove cataracts but are also becoming important procedures for correcting astigmatism. Cataract surgery improves vision in up to 95% of cases and prevents millions of Americans from going blind.

Nevertheless, considerable evidence suggests that, because of the ease and relative safety of the procedure, it may be performed more often than needed. Patients having operations now tend to have better preoperative vision than those operated on 10 or 20 years ago. In a study of 800 cataract operations, 25% of the patients said that clouding had had no obvious effect on their lives before the procedure.

Advantages of Surgery

Cataract surgery is very successful. It has the following advantages:

Indications for Surgery

In general, surgery is indicated for people with cataracts under the following circumstances:

These guidelines are general, however. Whether surgery is appropriate or not further depends on the cataract patient's specific condition and needs. Some examples include the following:

Because of the risks, albeit small ones, of poorer vision or blindness, no one should be forced to have cataract surgery if they don't want it or are not strong enough to undergo the procedure. If there are any doubts about whether or not to undergo cataract surgery, a second opinion should be considered.

Questions for the Ophthalmologist

The patient should ask the ophthalmologist the following questions before agreeing to cataract surgery:

  • Is my cataract surgery an emergency?
  • Are the cataracts the only cause of my poor vision?
  • How much experience do you have with this procedure?
  • Do I have other eye diseases that might complicate surgery or reduce my benefit?
  • Do I have other health problems that might further complicate eye surgery?
  • Will you be able to implant an intraocular lens?
  • What type of procedure will you use?
  • Will I have to stay in the hospital overnight?
  • Afterwards, what are my chances of having poorer vision or becoming totally blind in that eye?
  • How well should I ultimately be able to see out of the operated eye?
  • How long will it take to heal?
  • How long will it take to achieve my best eyesight?
  • Will I have to wear glasses or contact lenses after surgery?
  • When will I get my final eyeglass prescription?
  • How soon after surgery will I be able to see well enough to go back to work? Drive a car? Return to full activity?
  • What will the surgery cost?

Preparation for Surgery

Cataract surgery is now usually done as an outpatient procedure under local anesthesia and takes less than an hour. Preoperative preparations may include:

Surgical Procedures

All cataract procedures involve removal of the cataract-affected lens and replacing it with an artificial lens.

Phacoemulsification. Phacoemulsification ( phaco means lens, emulsification means to liquefy) is now the most common cataract procedure in the United States and accounts for 85% of cases. Benefits are greater than with standard extracapsular surgery, and it may be particularly helpful for people with diabetes.

The procedure generally involves:

Phacoemulsification requires only local anesthesia. Newer methods for administering local anesthesia produce few complications. Most phacoemulsification procedures now take about 15 minutes, and the patient is usually out of the operating room in about an hour. There is little discomfort afterward and visual rehabilitation takes about 1 - 3 weeks.

Phacoemulsification is sometimes combined with viscocanalostomy, a glaucoma surgical procedure, for patients who have both glaucoma and cataracts. Recent research suggests that phacoviscocanalostomy (as this combined procedure is called) is safe and effective for this group of patients.

Surgeons in the U.S. and Europe are currently investigating Microphaco, a new approach to cataract surgery that uses two smaller (micro) incisions. The smaller incisions measure about 1.6 mm compared to the traditional 3 mm. Experts say this procedure is expected to revolutionize refractive and cataract surgery.

Other Lens Removal Techniques . The AquaLase device uses pulses of fluid to wash away the clouded lens. Some experts believe this approach causes less trauma to the eye, and allows for a quicker recovery time for the patient, than the ultrasound used in phacoemulsification.

Extracapsular or Intracapsular Cataract Extraction. Extracapsular cataract extraction was the original standard procedure, but is now generally used only in patients who have an extremely hard lens. It typically involves the following steps:

It takes about 2 - 4 weeks to completely restore vision.

Replacement Lenses and Glasses

With the clouded lens removed, the eye cannot focus a sharp image on the retina. A replacement lens or eyeglass are therefore needed:

Intraocular Lenses (IOL). In about 90% of cataract operations, an artificial lens, known as an intraocular lens (IOLs), is inserted. Until recently, IOLs used a pair of little spring-loaded loops to hold the lens in place. Most IOLs are now foldable, which makes insertion easier. In fact, a prefolded lens is now available that unrolls to fit the eye as body temperature warms it.

IOLs are available as monofocal or multifocal. Monofocal lenses correct only one type of vision range (such as distance vision). Multifocal lenses are designed for patients who need correction for a range of vision– from near through distance. A 2006 study suggested that the Tecnis IOL works particularly well for patients who require a multifocal IOL.

Although all the lens materials are presumably chemically inert, there are some reports of specific problems, notably a risk for causing a reaction that leads to the development of secondary cataracts, a condition called posterior capsular opacification. IOLs include the following materials:

Other materials are under investigation.

IOL brands include:

IOLs are designed to improve specific aspects of vision. The choices include:

The patients and the doctor must make these decisions based on specific visual needs.

Contact Lenses or Cataract Glasses. A few patients do not receive a new lens and rely solely on corrective eyeglasses or contact lenses. Such patients may include:

In such cases, the patient typically returns to the ophthalmologist for a check up the day after surgery, and three additional check-ups are scheduled over a 2-month period. The ophthalmologist can usually give a final prescription for eyeglasses or contact lenses about three months after surgery.

Sometimes a patient has two cataracts and needs to wear glasses between the first and second operation. They are particularly troublesome during this period. The treated eye will see images magnified while the other eye will view them as they actually are, and the brain cannot blend the two images. This is a temporary state that is resolved by the second operation.

Complications of Cataract Surgery

Modern cataract surgery is one of the safest of all surgical procedures. Most complications, even if they occur, are not serious. They can include the following:

Glaucoma
Glaucoma is a condition of increased fluid pressure inside the eye. The increased pressure causes compression of the retina and the optic nerve which can eventually lead to nerve damage. Glaucoma can cause partial vision loss, with blindness as a possible eventual outcome.

Phacoemulsification does have some specific complications, although they are rare, particularly with experienced eye surgeons. They include:

In about 30% of cases patients develop secondary cataracts within 1 - 5 years after either procedure, which require different treatment choices.

Preventing Infection and Reducing Swelling. The ophthalmologist may prescribe the following medications:

In one study, applying an ice pack for 2 hours immediately after phacoemulsification improved comfort level and reduced inflammation, even days after the operation. This simple procedure has no adverse effects and patients should discuss it with their surgeons before the operation.

Factors That Increase Risk for Complications. The risks of complications are greater for the following people:

Postoperative Care

Returning Home and Follow-up Visits.

Protecting the Eye. Postoperative protection of the eye typically involves:

Avoiding Glaucoma. Cataract surgery can cause glaucoma, a condition in which the pressure of fluids inside the eye rises dangerously. It is very important to minimize any activity that increases internal eye pressure. Postoperative cataract patients take the following precautions:

Treatment for Patients with Accompanying Eye Conditions

Cataracts and Glaucoma. For patients with both glaucoma and cataracts, experts recommend:

Cataracts and Corneal Disease. Patients who have both cataracts and corneal disease may undergo one of the following:

Recovery of vision is usually much more rapid after the combined procedure than after the sequential procedures. Performing the procedures sequentially may also carry a higher rejection rate of the implant, although a 2003 study found no differences in failure rates between the two approaches after a year.

In any case, many experts recommend that for most patients the sequential procedures may be the better option because it appears to have fewer of the following complications than with the combined procedure:

The rate of these errors still depends on the skill of the surgeon and the power of the implanted lens no matter what approach is used.

Secondary Cataracts (Posterior Capsular Opacification) and Their Treatments

About 30% of patients who undergo extracapsular cataract surgery develop a secondary "after-cataract" called posterior capsular opacification . Posterior capsular opacification generally occurs because of the following events:

According to a 2001 study, the probability of developing a secondary cataract was 6% at 1 year, 15% at 2 years, 23% at 3 years, and 38% at 9 years. The risk is lower with phacoemulsification. Secondary cataracts are more likely to occur in younger patients, in those with diabetes, or when cataract surgery is combined vitrectomy (clearance of debris from the fluid in the eye).

Preventing Posterior Capsular Opacification. Studies suggest that acrylic lenses pose the lowest risk for posterior capsular opacification. A number of substances to prevent posterior capsular opacification are under investigation, including tranilast eyedrops, new lens materials, special capsular rings inserted during phacoemulsification, and new coatings on the implanted lens.

Treatment Decisions for Cataracts in the Second Eye. If a person has a cataract in a second eye, the issues for decision making are the same as for the first eye. The time of the procedure in the case of two cataracts is unclear. Doctors have long recommended that surgery on the second eye should be postponed until the first eye has healed and the results known (about a year).

One study has called this recommendation into question. It was conducted in England, where for budgetary reasons, there are long waits for second-eye cataract surgeries. In the study, patients who waited 7 - 12 months for the second-eye surgery reported significant difficulty in reading and performing ordinary tasks during the waiting period. Only 1% of patients who had the second surgery within 6 weeks reported having trouble seeing. In addition, 70% of those who waited experienced problems in depth perception, which can cause difficulty in walking and driving; only 12% who didn't wait reported this problem. Patients with double cataracts should discuss all options with their surgeon.

Treatment for Posterior Capsular Opacification. The standard treatment is laser surgery known as a YAG capsulotomy . (Capsulotomy means cutting into the capsule, and YAG is an abbreviation of yttrium aluminum garnet, the laser most often used for this procedure.)

Complications. Laser surgery has become so commonplace that some ophthalmologists use it after cataract surgery to prevent later clouding. However, laser surgery carries its own risks and possible complications, similar to those of cataract surgery itself, and can also lead to poorer vision or blindness. About 1% of laser surgery patients develop a detached retina, which is much higher than the risk from the original cataract surgery.

In some people, particularly those with glaucoma or who are severely nearsighted, the pressure in the eye may spike after laser surgery. Certain drugs used for treating glaucoma, such as dorzolamide (Trusopt) or apraclonidine (Iopidine), may helpful for preventing this occurrence. It is strongly recommended, however, that this surgery not be performed to prevent a secondary cataract, but only if the lens capsule clouds up again.

Treating Cataracts in Children

Infants

Treatment of infants first depends on whether one or both eyes are affected:

  • For infants born with cataracts in one eye, the American Academy of Ophthalmology recommends surgery as soon as possible, by 4 months or ideally even earlier. The procedure is followed by contact lens correction and patching of the unaffected eye. Although this approach is successful in many cases, some children still become blind in the affected eye. There is also a high risk for glaucoma after surgery.
  • In infants with cataracts in both eyes, surgery is not always an option. In some cases, it may be performed sequentially, with the second eye operated on a few days after the first. Phacoemulsification appears to pose a much higher risk for secondary cataracts than standard lens removal.

Toddlers and Older Children

Intraocular lens replacement is now becoming standard treatment for children 2 years and older.


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