FACTOID # 7: The top five best educated states are all in the Northeast.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
RELATED ARTICLES
People who viewed "Cataracts" also viewed:
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Cataracts

Cataract is also used to mean a waterfall or where the flow of a river changes dramatically. It comes from the Greek word meaning "downrush" or "to dash down" or the Latin "cataract" meaning a waterfall, a floodgate or a portcullis.



Enlarge
Normal vision. Courtesy NIH National Eye Institute
Enlarge
The same view with a cataract.

A cataract is any opacity which develops in the crystalline lens of the eye or in its envelope. Cataracts form for a variety of reasons, including infrared and microwave exposure, secondary effects of diseases such as diabetes, or simply due to advanced age; they are usually a result of denaturation of lens proteins. Genetic factors are often a cause of congenital cataracts and may also play a role in predisposing someone to cataracts. Some cataract formation is to be expected in any person over the age of 70. Fully half of all people between the ages of 65 and 74 and about 70% of those over 75 have some cataract formation. Cataracts may also be produced by eye injury or physical trauma.


Cataracts may be partial or complete, stationary or progressive, hard or soft. An early technique to remove cataracts was couching, which involved using a thin needle to remove the clouding. This technique is known to have existed in Roman times and continued to be used throughout the Middle Ages and continues to be used in underpriveleged "Third world" countries today.


The most effective and common treatment for is cataract surgery to remove the cloudy lens. There are two types of surgery that can be used to remove cataracts, extra-capsular and intra-capsular surgery. Extra-capsular surgery consists of removing the lens but leaving the back half of the lens capsule intact. High frequency sound waves (phacoemulsification) are sometimes used to break up the lens before extraction. Intra-capsular surgery involves removing the entire lens of the eye, including the lens capsule, but it is rarely performed in modern practice. The lens is then replaced with a plastic lens (an intraocular lens implant) which remains permanently in the eye.


Cataract operations are mostly performed under a local anaesthetic and the patient will be allowed to go home the same day. Complications after cataract surgery are uncommon. Many people (up to 50%) can develop a posterior capsular opacification after initial cataract surgery. This is a thickening and clouding of the lens capsule (which was left behind when the cataract was removed) and it can be easily corrected using a laser to make holes in the capsule for the person to see through.


Previously, polymethylmethacrylate was used as the lens material. Advances have brought about the use of silicone acrylate which is a soft material. This allows the lens to be folded and injected into the eye through a smaller incision.

Enlarge
Human eye cross-sectional view. Courtesy NIH National Eye Institute

External links

  • NHS Best Treatments Site (http://www.besttreatments.co.uk/btuk/electsurgery/cataract_surgery)
  • eMedicine Health (http://www.emedicinehealth.com/articles/14319-1.asp)



  Results from FactBites:
 
Cataract - Wikipedia, the free encyclopedia (1249 words)
Cataracts form for a variety of reasons, including long-term ultraviolet exposure, secondary effects of diseases such as diabetes, or simply due to advanced age; they are usually a result of denaturation of lens proteins.
Genetic factors are often a cause of congenital cataracts and positive family history may also play a role in predisposing someone to cataracts at an earlier age, a phenomenon of "anticipation" in pre-senile cataracts.
In either extra-capsular surgery or intra-capsular surgery, the cataractous lens is removed and replaced with a plastic lens (an intraocular lens implant) which remains permanently in the eye.
Cataract (526 words)
A cataract is a cloudy or opaque area in the lens of the eye.
Cataracts are accelerated by environmental factors, such as smoking or exposure to other toxic substances, or they may develop at any time after an eye injury.
Congenital cataracts can also be caused by infections of the mother during pregnancy such as rubella, or associated with metabolic disorders such as galactosemia.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m