Types of Cataracts

An eye consists different layers. The outermost layer is the capsule, the layer inside capsule is cortex & the inner most layer is the nucleus. Cataract can develop in any of these layer and are named depending on its location.

• A nuclear cataract is located in the center of the lens. The nucleus tends to darken, changing from clear to yellow and sometimes brown.
  
  
• A cortical cataract affects the layer of the lens surrounding the nucleus. The cataract looks like a wedge or a spoke.
  
  
• A posterior capsular cataract is found in the back outer layer of the lens. This type often develops more rapidly.
  
  

What Causes Cataracts?

The lens is mostly made of protein and water, changes in protein and lens fiber can cause clouding. Most cataracts are caused because of age related changes in the eye that causes clouding. Some other known reasons for clouding of lens are as follows:

• Diabetes mellitus: People with diabetes are at higher risk for cataracts.
  
  
• Drugs: Certain medications are associated with cataract development. These include:
  
  • Corticosteroids
    
  • Chlorpromazine and other phenothiazine-related medications
    
• Ultraviolet radiation: Studies show an increased chance of cataract formation with unprotected exposure to ultraviolet (UV) radiation.
  
  
• Smoking: There is possibly an association between smoking and increased lens cloudiness.
  
  
• Alcohol: Several studies show increased cataract formation in patients with higher alcohol consumption compared with people who have lower or no alcohol consumption.
  
  
• Nutritional deficiency: Although the results are inconclusive, studies suggest an association between cataract formation and low levels of antioxidants (for example, vitamin C, vitamin E and carotenoids). Further studies may show that antioxidants can help decrease cataract development.
  

Cataract are rarely present during birth or can develop shortly after, this can be inherited or because of infection such as rubella in mother during pregnancy. A cataract may also develop following an eye injury or surgery for another eye problem, such as glaucoma.

How is Cataract diagnosed?

Cataract can be diagnosed by comprehensive eye examination which includes visual activity to measure up to what distance is a cataract limiting clear near & distant vision, refraction to check need for changing lens or eyeglass prescription, Evaluation of the lens under high magnification and illumination to determine the extent and location of any cataracts, Evaluation of the retina of the eye through a dilated pupil, Measurement of pressure within the eye, Supplemental testing for color vision and glare sensitivity.

Further testing may be required to determine how much is cataract affecting vision or are the other eye disease affecting the vision.

How Is a Cataract Treated?

The treatment of Cataract is based on the amount of visual impairment they cause. If cataract hardly affects vision or not at all affects it, no treatment may be required. In some cases changing eyeglasses lens may be the only needed, whereas when cataract progresses to point where it affects normal daily tasks, surgery may be required.

Cataract surgery involves removing of affected lens and replacing it with an artificial lens. Such lens requires no special care and can help improving vision. As with any surgery, Cataract surgery also have risk of infection and bleeding and increased chances of retinal detachment.

Two approaches to cataract surgery are generally used:

• Small-incision cataract surgery: This involves making an incision in the side of the cornea (the clear outer covering of the eye) and inserting a tiny probe into the eye. The probe emits ultrasound waves that soften and break up the lens so it can be suctioned out. This process is called phacoemulsification.
  
  
• Extracapsular surgery: This requires a somewhat larger incision in the cornea so that the lens core can be removed in one piece. The natural lens is replaced by a clear plastic lens called an intraocular lens (IOL). When implanting an IOL is not possible because of other eye problems, contact lenses and, in some cases, eyeglasses may be an option for vision correction.
  

Cataract surgery is one of the safest and most effective types of surgery performed in the United States today. Approximately 90 percent of cataract surgery patients report better vision following the surgery.