What is an Eye Cataract?

Latin: cataracta meaning "waterfall"

Greek: kataraktes and katarrhaktes, from katarassein meaning "to dash down" (kata-, "down"; arassein, "to strike, dash").
As rapidly running water turns white, the term may later have been used metaphorically to describe the similar appearance of mature ocular opacities.

In dialect English a cataract is called a pearl, as in "pearl eye" and "pearl-eyed".

Cross-section illustration of eye, with major structures labeled.

The natural lens

• The natural lens, like the cornea, makes sure that the light rays which enter the eye are refracted.
  
• This results in a sharp image on the retina.
  
• The lens has a diameter of about 9 mm, is 5 mm thick and has a convex front and rear side.

The lens is clear and transparent which enables light to pass through it easily.

Cataract

• In the young, the lens is clear and transparent.
  
• Lens opacity caused by old age or other reasons affects the clarity and the visual acuity. This is a cataract.
• Cataract is the most common cause of vision impairment and blindness in the world.
• Cataract may originate in various different locations in the lens.
• Its onset may be in the middle of the lens, on the side or in other positions.
• Cataract usually starts out in the middle of the lens, in which case it is referred to as nuclear cataract.

Symptoms of cataract

The most common symptoms of cataract are:

• blurred vision (X)
  
• fewer details
• double vision (diplopia)
• sensitivity to light (Photophobia - not scared, med term for sensitive to light) (X)
  
• difficulty reading (X)
• diminished night vision
• changed prescription power for glasses
  

Senile cataract

• Senile cataract is by far the most common type of cataract.
  
• Senile cataract can be compared to getting wrinkles and turning grey.
  
• Due to an aging population, this type of cataract is on the increase.

Cataract caused by a disorder or an accident

Cataract can also occur in young people. In this case, it is usually caused by trauma, for instance when a foreign object gets lodged in the eye or by a blow to the eye. Other causes which may lead to the development of cataract in younger individuals are:

• diabetes;
• a surgical treatment of the eye (vitrectomy)
• long-term exposure to ultraviolet light, sunlight
• long-term use of certain types of medication, such as cortisone
• heavy smoking
• heavy drinking
  

Congenital cataract

In rare cases, cataract can be congenital. Congenital cataract may occur because the mother had rubella during pregnancy. Other problems during pregnancy can also cause cataract. Sometimes congenital cataract is an independent problem, but it can also be part of another syndrome.


http://www.ophtec.com/consumer/en/cataract/what-is-cataract-