Cataract surgery

Anatomy or system affected: Eyes

Definition: The surgical management of cataracts

Indications and Procedures

Cataract surgery refers to the surgical removal and replacement of the lens from the eye, generally because of a decrease in vision or other visual complaints, such as difficulty with night vision, glare, or loss of contrast, due to cataracts. Cataracts form when the lens of the eyes becomes clouded or discolored. Although cataracts can form during early childhood, they are most common in adults over the age of sixty-five. The decision to undergo cataract surgery depends most often on the individual’s subjective threshold for what constitutes unacceptable vision.

Every eye contains a lens that allows images to be focused on the retina, much like a camera focuses light. Cataracts can develop in two different ways: the protein within the lens of the eye clumps together, causing blurred vision, or the lens develops a yellow or brown tint, reducing the clarity of vision. With age, most people develop some degree of opacity in their lens, which can only be remedied by surgically removing the lens and replacing it with an artificial one. The artificial lens can be made from a variety of materials, such as silicone, acrylic, or other biocompatible synthetic substances.

Because of the refinement in instrumentation and technique, general anesthesia is rarely indicated in cataract surgery, and the procedure is often performed on an outpatient basis. Local anesthesia is generally administered by injection of the anesthetic solution around the eye or by placing anesthetic drops on the eye. The surgical approach to lens extraction depends to some extent on the nature of the cataract and the surgeon’s preference. Most surgeons use a high-frequency ultrasound device to break the cataract into small fragments, which are then aspirated with the same device (phacoemulsification). This procedure is often performed through a very small incision, which may be left to close by itself or be closed with one small suture. Under certain circumstances, the ophthalmologist may elect to remove the entire lens in a single piece (extracapsular surgery), in which case a larger opening is needed into the eye to gain access to the cataract.

Once the cataract is removed, a clear artificial intraocular lens (IOL) is often placed in its position to allow the eye to continue to focus light properly. The IOL may be single-focus (focusing at only one distance) or multifocal (focusing at both near and far distances). In general, if cataracts have formed in both eyes, cataract surgery is performed on one eye at a time, allowing the first eye to heal prior to the second procedure. The length of the procedure is often less than one hour, provided there are no complications or special needs.

In most cases, the patient returns home the same day and may wear a patch over the eye until the next postoperative day, when they are seen for follow-up. The patient is asked to start taking a combination of antibiotics and anti-inflammatory agents to prevent infection and reduce inflammation. Some ophthalmologists also suggest using these drops prior to surgery to minimize the risk of infection and inflammation even further. Visual recovery varies greatly among individuals and may be as short as a day or as long as eight weeks. Following surgery, patients are instructed by the surgeon not to take part in strenuous activities, rub their eyes, or lift heavy weights for at least one week or longer. No water, soap, dirt, or dust may get into the eye during recovery.

Uses and Complications

Although cataracts are mostly a condition affecting older adults, they can occur at any age and even in newborns. Cataracts may have various causes, although the most common is related to simple aging and does not necessarily reflect a significant disease of the eye or the body. The presence of cataracts in young children or young adults must be promptly addressed, especially in newborns. Potentially more serious conditions may mask themselves as cataracts in the young child. Therefore, unlike the adult cataract, the progression of which can be carefully followed over time, the cataract in the newborn must be quickly referred to an ophthalmologist for surgical care.

With the many refinements in technique and technology, the overall morbidity of this procedure has significantly diminished, and most patients who undergo cataract surgery find it to be a positive life-altering experience. As with most surgical procedures, infection and bleeding can occur during cataract surgery. Although exceedingly rare, a resulting eye infection, known as endophthalmitis, can have devastating consequences and must be addressed immediately. The signs and symptoms of endophthalmitis include decreased vision, pain, and redness. A more common complication of surgery is swelling of the retina (macular edema). This condition may lead to suboptimal vision following surgery but can generally be treated with anti-inflammatory drops. Finally, one or more fragments of the lens may become dislodged in the eye as a result of a rupture of the capsule surrounding the cataract. If the surgeon deems it unsafe to proceed further, then the eye may be closed and approached at a later time with the help of a retinal surgeon, who can then safely remove any remaining fragments from the eye. It is not uncommon for a secondary cataract to form on the implanted IOL; this is treated using a laser technique called "posterior capsulotomy." Other rare but potential complications include the loss of the clarity of the cornea, retinal detachment, glaucoma, or long-standing inflammation.

Perspective and Prospects

The word “cataract” is derived from a Greek and Latin word meaning “waterfall,” referring to the visible veil that forms in the pupil. Cataracts constitute the most common cause of preventive blindness throughout the world. Globally, cataracts are the leading cause of blindness, accounting for 50 percent of its incidence. No medicinal treatments are currently available for cataracts. There is some evidence that a healthy lifestyle with proper precaution against ultraviolet (UV) light can slow the formation or progression of cataracts. Risk factors for developing cataracts include diabetes, certain genetic disorders, cigarette smoking, heavy alcohol use, high blood pressure, and obesity. Still, more than half of Americans will develop cataracts by the time they reach eighty years old.

Future trends in the management of cataracts point to less invasive surgical approaches, with smaller incisions and devices that produce less collateral heat. Laser devices for cataract surgery continue to improve and may one day equal or surpass ultrasound devices in their ability to address most cataracts safely. In the twenty-first century, doctors began using a tool called intraoperative aberrometry (ORA), which takes a more accurate measurement of the synthetic lens that is used to replace the original lens with the cataract.

Significant progress continues to be made in the realm of artificial intraocular lenses. Many IOLs can now be folded or injected into the eye through very small incisions. Some progress has been made to manufacture lenses that provide true accommodation, much like a young individual’s eyes, thus obviating the need for reading glasses. Finally, with the advent of better antibiotic solutions, the potential risk of infection is significantly reduced.

Bibliography

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