page_title: Cataract
section_title: Surgical
hierarchical_section_title: Cataract / Treatment / Surgical
caption_attribution_description: Aftercataract - Posterior capsular opacification post-cataract surgery(seen on retroillumination)
context_page_description: A cataract is an opacification of the lens of the eye which leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble with bright lights, and trouble seeing at night. This may result in trouble driving, reading, or recognizing faces. Poor vision caused by cataracts may also result in an increased risk of falling and depression. Cataracts cause half of all cases of blindness and 33% of visual impairment worldwide.
  Cataracts are most commonly due to aging but may also occur due to trauma or radiation exposure, be present from birth, or occur following eye surgery for other problems. Risk factors include diabetes, smoking tobacco, prolonged exposure to sunlight, and alcohol. The underlying mechanism involves accumulation of clumps of protein or yellow-brown pigment in the lens that reduces transmission of light to the retina at the back of the eye. Diagnosis is by an eye examination.
  Prevention includes wearing sunglasses, a wide brimmed hat, eating leafy vegetables and fruits, and avoiding smoking. Early on the symptoms may be improved with glasses.
context_section_description: The appropriateness of surgery depends on a person's particular functional and visual needs and other risk factors. Cataract removal can be performed at any stage and no longer requires ripening of the lens. Surgery is usually "outpatient" and usually performed using local anesthesia. About 9 of 10 patients can achieve a corrected vision of 20/40 or better after surgery.
  Several recent evaluations found that cataract surgery can meet expectations only when significant functional impairment due to cataracts exists before surgery. Visual function estimates such as VF-14 have been found to give more realistic estimates than visual acuity testing alone. In some developed countries, a trend to overuse cataract surgery has been noted, which may lead to disappointing results.
  Phacoemulsification is the most widely used cataract surgery in the developed world. This procedure uses ultrasonic energy to emulsify the cataract lens. Phacoemulsification typically comprises six steps:
  Anaesthetic – The eye is numbed with either a subtenon injection around the eye (see: retrobulbar block) or topical anesthetic eye drops. The former also provides paralysis of the eye muscles.
  Corneal incision – Two cuts are made at the margin of the clear cornea to allow insertion of instruments into the eye.
  Capsulorhexis – A needle or small pair of forceps is used to create a circular hole in the capsule in which the lens sits.
  Phacoemulsification – A handheld ultrasonic probe is used to break up and emulsify the lens into liquid using the energy of ultrasound waves.  The resulting 'emulsion' is sucked away.
  Irrigation and aspiration – The cortex, which is the soft outer layer of the cataract, is aspirated or sucked away. Fluid removed is continually replaced with a saline solution to prevent collapse of the structure of the anterior chamber (the front part of the eye).
  Lens insertion – A plastic, foldable lens is inserted into the capsular bag that formerly contained the natural lens. Some surgeons also inject an antibiotic into the eye to reduce the risk of infection. The final step is to inject salt water into the corneal wounds to cause the area to swell and seal the incision.
  A Cochrane review found little to no difference in visual acuity as a function of the size of incisions made for phacoemulsification in the range from ≤ 1.5 mm to 3.0 mm.
  Extracapsular cataract extraction (ECCE) consists of removing the lens manually, but leaving the majority of the capsule intact. The lens is expressed through a 10- to 12-mm incision which is closed with sutures at the end of surgery. ECCE is less frequently performed than phacoemulsification, but can be useful when dealing with very hard cataracts or other situations where emulsification is problematic. Manual small incision cataract surgery (MSICS) has evolved from ECCE. In MSICS, the lens is removed through a self-sealing scleral tunnel wound in the sclera which, ideally, is watertight and does not require suturing. Although "small", the incision is still markedly larger than the portal in phacoemulsion. This surgery is increasingly popular in the developing world where access to phacoemulsification is still limited.
  Intracapsular cataract extraction (ICCE) is rarely performed. The lens and surrounding capsule are removed in one piece through a large incision while pressure is applied to the vitreous membrane. The surgery has a high rate of complications.
caption: Slit lamp photo of posterior capsular opacification visible a few months after implantation of intraocular lens, seen on retroillumination
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