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Cataract and Cataract Surgery

Cataract - a common cause of gradual vision loss ­is opacity of the lens or the lens capsule of the eye. The clouded lens blocks light shining through the cornea. This, in turn, blurs the image cast onto the retina. As a result, the brain interprets a hazy image.

Cataracts commonly affect both eyes, but each cataract progresses independently. Exceptions are traumatic cataracts, which are usually unilateral, and congenital cataracts, which may remain stationary. Cataracts are most prevalent in people over age 70. Surgery restores vision in about 95% of patients.


Cataracts are classified by their causes:

  • Senile cataracts develop in elderly people, probably because of chemical changes in lens proteins.
  • Congenital cataracts occur in neonates from inborn errors of metabolism or from maternal rubella infection during the first trimester; these cataracts may also result from a congenital anomaly or from genetic causes. Transmission is usually autosomal dominant; however, recessive cataracts may be sex-linked.
  • Traumatic cataracts develop after a foreign body injures the lens with sufficient force to allow aqueous or vitreous humor to enter the lens capsule.
  • Complicated cataracts occur secondary to uveitis, glaucoma, retinitis pigmentosa, or retinal detachment. They can also occur with systemic disease, such as diabetes, hypoparathyroidism, or atopic dermatitis or from ionizing radiation or infrared rays.
  • Toxic cataracts result from drug or chemical toxicity with ergot, dinitrophenol, naphthalene, and phenothiazines.


The following are the most common symptoms ofcataracts. However, each individual may experience symptoms differently. Symptoms may include:

  • cloudy or blurry vision
  • lights appear too bright and/or present a glare or a surrounding halo
  • poor night vision
  • multiple vision
  • colors seem faded
  • increased nearsightedness - increasing the need to change eyeglass prescriptions
  • distortion of vision in either eye

Often in the disease's early stages, you may not notice any changes in your vision. Since cataracts tend to grow slowly, your vision will worsen gradually. Certain cataracts can also cause a temporary improvement in close-up vision, but this is likely to worsen as the cataract grows. The symptoms ofcataracts may resemble other eye conditions. Consult a physician for diagnosis.

Diagnostic tests

  • Standard ophthalmic exam , including slit lamp examination
  • Ultrasonography of the eye in preparation for cataract surgery

Other tests that may be done (rarely) include:

  • Glare test
  • Contrast sensitivity test
  • Potential vision test
  • Specular microscopy of the cornea in preparation for cataract surgery


Surgical lens extraction and implantation of an intraocular lens (IOL) to correct the visual deficit is the treatment for a patient with cataract. The surgery is usually performed as a same-day, or outpatient, procedure.

Surgical procedures include the following:

  • Extracapsular cataract extraction, the most common procedure, involves removing the anterior lens capsule and cortex and leaving the posterior capsule intact. In this procedure, the surgeon implants a posterior chamber IOL where the patient's own lens used to be. This procedure is used for patients of all ages.
  • Intracapsular cataract extraction involves removing the entire lens within the intact capsule by cryoextraction (the moist lens sticks to an extremely cold metal probe for easy and safe removal with gentle traction). After the surgeon removes the lens, he implants an IOL in either the anterior or posterior chamber. If the patient doesn't receive an IOL, he'll use contact lenses or aphakic glasses to correct vision.
  • Phacoemulsification relies on ultrasonic vibrations to fragment the lens. The broken pieces are removed by aspiration.

Possible complications of surgery include loss of vitreous (during surgery), wound dehiscence from loosening of sutures and flat anterior chamber or iris prolapse into the wound, hyphema, pupillary block glaucoma, retinal detachment, and infection. In addition, a patient with an IOL implant may experience improved vision almost immediately; however, the IOL corrects distance vision only. The patient also needs either corrective reading glasses or a corrective contact lens, which can be fitted 4 to 8 weeks after surgery.

If the patient didn't receive an IOL, he may receive temporary aphakic cataract glasses. Then, sometime between 4 and 8 weeks after surgery, he has a refraction examination for permanent glasses.

Some patients who have an extracapsular cataract extraction develop a secondary membrane in the posterior lens capsule (which has been left intact), causing decreased visual acuity. This membrane can be removed by the Nd:YAG laser, which cuts an area from the membrane center, thus restoring vision. However, laser surgery alone can't remove a cataract.


Although cataracts have no scientifically proven prevention, it is sometimes said that wearing ultraviolet -protecting sunglasses may slow the development of cataracts. Regular intake of antioxidants (such as vitamin C and E) is theoretically helpful, but this is also not proven.

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