Cataract surgery

Definition

Cataract surgery is a procedure performed to remove a cloudy (natural) lens from the eye; usually an intraocular (artificial) lens is implanted at the same time. The removed lens, sometimes also called a crystalline lens, is called a cataract because the originally clear lens has turned cloudy. An ophthalmologist (commonly called an eye surgeon) usually performs such surgeries on an outpatient basis within a surgical center, hospital, or other professional medical facility. The commonly performed procedure, which takes less than an hour, is generally safe and nearly risk free.


Demographics

Nearly all cataract surgeries are performed on older people. As the eyes age, cataracts form on the lens of the eyes, which cause blurry vision, difficulties looking at bright lights, and other such vision problems. According to the National Institutes ofHealth, over 50% of people in the United States over the age of 80 years have a cataract or have had cataract surgery. Normally, people will have cataract surgery when the eyes degrade enough so that it is increasingly difficult to carry out daily activities of life. Often times, people, especially elderly adults, have other eye problems, such as macular degeneration, which are difficult to treat when cataracts are present. In such cases, it is often advisable to have the cataracts removed.

Purpose

The purpose of cataract surgery is to restore clear vision. It is indicated when cloudy vision due to cataracts has progressed to such an extent that it interferes with normal daily activities. Other symptoms of cataracts include colors that fade, excessive glare, inability to see well at night, double vision, and numerous changes in vision prescriptions (for eye glasses or contacts). It is one of the most commonly performed surgical procedures in the world.



Precautions

Cataract surgery is not performed on both eyes at once. To avoid risking blindness in both eyes in the event of infection or other catastrophe, the first eye is allowed to heal before the cataract is removed from the second eye.

The presence of cataracts can mask additional eye problems, such as retinal damage, that neither doctors nor patients are aware of prior to surgery. Since such conditions will continue to impair sight after cataract removal if they are not identified and treated, the eventual outcome of cataract surgery will depend on the outcome of other problems.

In 1997 and 1998, evidence that cataract surgery can contribute to the progression of age-related macular degeneration (ARMD) was published. ARMD is the degeneration of the central part of the retina. However, as of 2010, studies have not shown such a conclusive relationship. Whether cataract surgery contributes to the progression of ARMD is still up to debate in the medical community. Accordingly, ARMD patients with cataracts must weigh the possible risks of the loss of central vision, within four or five years, against shortterm improvement. When an ARMD patient chooses cataract surgery, the surgeon should shield the retina against bright light to protect it from possible lightinduced damage during surgery and install an intraocular lens capable of absorbing ultraviolet and blue light, which seem to do the most damage.

Description

Just before the start of the surgery, eye drops are placed in the eye to dilate the pupil. Local anesthetics are provided to de-sensitive (numb) the area around the eye.A sedative may be provided for anxious patients so they can relax. The patient will remain awake during the surgery but may feel sleepy.

There are two types of cataract surgery: intracapsular and extracapsular. Intracapsular surgery is the removal of both the lens and the thin capsule that surround the lens. This type of surgery was common before 1980, but it has since been displaced by extracapsular surgery. Removal of the capsule requires a large incision and does not allow comfortable intraocular lens implantation. Thus, people who undergo intracapsular cataract surgery have long recovery periods and have to wear very thick glasses.

Extracapsular cataract surgery is the removal of the lens where the capsule is left in place. Each year in the United States, over a million cataracts are removed this way. Physicians and researchers continue to improve cataract surgery methods. Research from France in 2003 said that cataract removal and non-penetrating glaucoma surgery can be combined in glaucoma patients.

There are two methods for extracapsular cataract surgery. The usual technique is phacoemulsification. A tiny incision (about 0.12-inch, or 3-millimeter, long) is made next to the cornea (the eye's outer covering) in the front of the eye, and an ultrasonic probe is used to break up (emulsify) the cataract into minute pieces, which are then removed by suction. Stitches may or may not be used to close the small incision point.

When the lens is too hard to be emulsified ultrasonically, the surgeon will use a slightly different technique called extracapsular extraction, which requires a larger incision. The extracapsular extraction is performed during phacoemulsification. During the process, an incision-one with a length of about 0.37 inch (9 millimeters) long-is made, and the whole lens (without its capsule) is removed through the incision. In this method, stitches are usually necessary. Both kinds of extracapsular cataract surgery leave the back of the capsule intact, so a silicone or plastic intraocular lens can be stably implanted in about the same location as the original lens.

The surgery takes about 30 to 60 minutes for one eye. Once completed the patient will have a clear, artificial lens implanted into the empty capsule. The implant, called an intraocular lens (IOL), is made of acrylic, plastic, or silicone. There are a variety of different IOLs that can be implanted. Some are flexible, while others rigid. Some are made so they block ultraviolet (UV) radiation, while others function like bifocal or trifocal eye glasses.

Preparation

Patients must have a pre-operation eye examination, which will include ultrasound analysis to make sure the retina (the innermost layer of the eye, containing the light receptors) is intact and also to measure eye curvature so that a lens with the proper correction can be implanted. The patient also will have a preoperative physical examination. In addition, patients start a course of antibiotic eye drops or ointment the day before surgery. Medications taken by the patient may be stopped under the advice of the surgeon. Such medications include any that may cause increased bleeding during surgery.

About 12 hours before the surgery, the physician may ask you to stop eating or drinking. The medical staff will also ask the patient to arrange for someone to remain at the surgical site to drive the patient home afterwards.

Aftercare

Proper post-operative care is especially important after cataract surgery. Patients will need someone to drive them home after the surgery and should not bend over or lift anything up for a few days after the surgery, or do anything strenuous for about two weeks. The sight through the repaired eye will be blurry over the first few days after surgery as the eye adjusts to the new lens. Patients should refrain from rubbing or pressing the eye, should wear glasses to protect their eye, and should wear a shield while sleeping so the eye will not be rubbed or bumped accidentally.

The patient will usually continue their antibiotic for two to three weeks and will also take anti-inflammatory medication for about the same length of time. If the patient experiences inflammation, redness, or pain, they should seek immediate medical treatment to avoid serious complications. If complications do not occur, the patient will normally visit the doctor a few days after the surgery and, then again, after a week and finally after a month.

Any type of after care is not necessary for the intraocular lens itself. It becomes a permanent part of the eye. The eye should be completely healed within eight weeks of the surgery.

Risks

Cataract surgery itself is quite safe and is almost always treated successfully; over 90% of the time, complications do not occur. However, complications can occur and should be noted by anyone thinking about cataract surgery. Possible complications include intraocular infection (endophthalmitis), central retinal inflammation (macular edema), post-operative glaucoma, retinal detachment, bleeding under the retina (choroidal hemorrhage), and tiny lens fragments in the back (vitreous) cavity of the eye, all of which can lead to loss of sight.

If the following symptoms occur, contact your doctor immediately:

  • Nausea, vomiting, or disproportionate amount of coughing
  • Loss of vision in the eye
  • Redness in the eye
  • Excessive, persistent pain (especially if pain medications are being used)
  • Flashes of light or floaters (spots) on the front of the eye.

An added risk of complications can also occur when other diseases are present. Such diseases may prevent an otherwise successful surgery from being completed satisfactorily. In such cases, vision may not be improved due to diseases present within the body, and especially those diseases of the eyes, such as glaucoma. Consequently, it may be wise to treat such diseases before having cataract surgery.

Since increased use of the phacoemulsification method of cataract surgery, researchers have noted a decline in cases of infection (endophthalmitis). This probably is because injectable intraocular lenses do not make contact with the ocular surface. In 2004, the FDA approved a new capsular tension ring for use in cataract surgery that helps prevent lens dislocation and other possible complications of surgery.

After cataract surgery, some patients develop posterior capsule opacification (PCO). This complication occurs when the back of the lens capsule becomes cloudy and sight is again degraded. However, if this happens, then a procedure called yttrium-aluminumgarnet (YAG) laser capsulotomy can be performed. The procedure allows light to pass through the clouded capsule, which solves the problem.

Normal results

Ordinarily, according to the National Institutes of Health, about 95% of patients experience improved visual acuity and improved perception of the vividness of colors, leading to increased abilities in many activities, including reading, needlework, driving, golf, and tennis, for example. This improvement in sight should be apparent within a few days after the surgery. In addition, sometimes implanted corrective lenses eliminate the need for eyeglasses or contact lenses. Researchers and manufacturers also continue to work to improve the lenses available in cataract surgeries, so that eventual vision and outcome are improved.