Cataract surgery, which is also called lens replacement surgery, is the removal of the natural lens (also called the "crystalline lens") of the human eye that has developed a cataract, an opaque or cloudy area. The eye's natural lens is usually replaced with an artificial intraocular lens (IOL).
Over time, metabolic changes of the crystalline lens fibres lead to the development of a cataract, causing impairment or loss of vision. Some infants are born with congenital cataracts, and environmental factors may lead to cataract formation. Early symptoms may include strong glare from lights and small light sources at night, and reduced visual acuity at low light levels.
During cataract surgery, the cloudy natural lens is removed, either by emulsification in place or by cutting it out. An IOL is usually implanted in its place to restore useful focus. Cataract surgery is generally performed by an ophthalmologist in an out-patient setting at a surgical centre or hospital. Local anaesthesia is normally used; the procedure is usually quick, and causes little or no pain and minor discomfort to the patient. Recovery sufficient for most daily activities usually takes place in days and full recovery about a month.
Well over 90% of operations are successful in restoring useful vision, and there is a low complication rate. Day care, high-volume, minimally invasive, small-incision phacoemulsification with quick post-operative recovery has become the standard of care in cataract surgery in the developed world. Manual small incision cataract surgery (MSICS), which is considerably more economical in time, capital equipment, and consumables, but provides comparable results, is popular in the developing world. Both procedures have a low risk of serious complications.
Description
Cataract surgery, also called lens replacement surgery, is the removal of the natural lens (also called the "crystalline lens") of the human eye that has developed a cataract, an opaque or cloudy area. The eye's natural lens is usually replaced with an artificial intraocular lens (IOL) to restore focus within a useful range of distances. It is the definitive treatment for vision impairment due to lens opacification.
A cataract is a cloudy area in the lens of the eye that causes visual impairment. Cataracts usually develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurred or double vision, halos around lights, sensitivity to glare from bright lights, and night blindness. This may result in difficulty driving, reading, or recognizing faces. Poor vision caused by cataracts may also increase the risk of falling and depression.
Cataracts most commonly occur due to aging, but may also be caused by trauma or radiation exposure, be present since birth, or may represent a complication of eye surgery aimed to solve other health problems. Risk factors include diabetes, longstanding use of corticosteroid medication, tobacco smoking, extended hyperbaric oxygen therapy, prolonged exposure to sunlight, and consumption of alcohol. Cataracts form when clumps of proteins or yellow-brown pigment accumulate in the lens, which reduces transmission of light to the retina at the back of the eye. Cataracts can be diagnosed via an eye examination.
Early symptoms of cataract may be improved by wearing specific types of glasses; if this does not help, cataract surgery is the only effective treatment. Surgery with implants generally results in better vision and an improved quality of life: however, the procedure is not readily available in many countries.
About 20 million people worldwide are blind due to cataracts, which cause 51% of all cases of blindness and 33% of visual impairment. They are the cause of approximately 5% of all cases of blindness in the United States, and nearly 60% of all cases in parts of Africa and South America. Blindness from cataracts occurs in between 10 and 40 children per 100,000 in the developing world, and between 1 and 4 children per 100,000 in the developed world. Cataracts become more common with age. In the United States, cataracts occur in 68% of those over the age of 80 years. They are more common in women, and less common in Hispanic and Black people.
Contraindications
Contraindications to cataract surgery include cataracts that do not cause visual impairment and medical conditions that predict a high risk of unsatisfactory surgical outcomes.