The word Cataract derives from the Latin word ‘cataracta’ that means “waterfall” and the Greek “kataraktes” and “katarrhaktes”, from “katarassein” which means “to dash down” (kata means “down”; arassein means “to strike, dash”).The term may later have been used metaphorically to relate the appearance of mature ocular opacities to the rapidly running water gradually turning white. In Latin, cataracta had another meaning suggesting “portcullis”, the name might have come about to denote the sense of “obstruction”. Early Persian physicians called it “nazul-i-ah” or “descent of the water”. It was then vulgarized into waterfall disease or cataract. It was believed that this kind of blindness was caused by an outpouring of infected humor into the eye. In dialect English a cataract is termed as pearl, as in “pearl eye” and “pearl-eyed”. Early cataract surgery was designed by the Indian surgeon, Sushruta in 6th century BC.
A cataract is a sort of clouding of the eye’s natural lens lying behind the iris and the pupil. It is not visible with the naked eye unless it becomes very cloudy. Cataracts change the clarity of the natural lens inside the eye that gradually affects visual quality. The lens plays a vital role in focusing unhindered light on the retina at the back of the eye. The retina converts light to a neurologic signal that the brain interprets as vision. Major cataracts block and disturb light passing through the lens, resulting in visual symptoms and complaints.
Cataract development is generally a very steady process of normal aging but can occasionally emerge rapidly. Many people are in fact ignorant about the fact that they have cataracts because of the gradual changes in their vision. Cataracts usually affect both eyes, but in most of the cases one eye is affected earlier than the other. Cataracts are very common as it affects approximately 60% of people over the age of 60, and over 1.5 million cataract surgeries take place in the United States each year.
Cataracts are often compared to a foggy windshield of a car or dirty lens of a camera.
Cataracts may cause a variety of complications and visual changes, such as:
- Blurred vision
- Difficulty with glare(often with bright sun or automobile headlights while driving at night)
- Dulled color vision
- Increased nearsightedness along with frequent changes in eyeglass prescription Double vision in one eye.
Some people detect a phenomenon known as “second sight”. In this case one’s reading vision improves due to their increased nearsightedness from swelling of the cataract. A change in glasses may seem to be beneficial initially once vision begins to change from cataracts; however, once cataracts continue to develop and opacify, vision becomes hazy and even stronger glasses or contact lenses will be ineffectual to improve sight.
Cataracts are influenced by a variety of reasons, such as:
- Long-term exposure to ultraviolet light
- Exposure to radiation
- Secondary effects of diseases such as diabetes, hypertension and advanced age
- Trauma (possibly much earlier)
These are typically a result of denaturation of lens protein. Genetic factors are often leads to congenital cataracts. Positive family history may also predispose someone to cataracts at a younger age. This is an incident of “anticipation” in pre-senile cataracts. Cataracts may also happen due to an eye injury or physical trauma. A study among Ice Land air pilots revealed that commercial airline pilots are three times more likely to have cataracts than people with non-flying jobs. This is thought to be caused due to too much exposure to radiation coming from outer space. Cataracts are also unusually familiar with persons exposed to infrared radiation, namely glassblowers who experience “exfoliation syndrome”. Exposure to microwave radiation also results in cataracts. Atopic or allergic conditions are also known to accelerate the progression of cataracts, especially in children.
There are different types of cataracts, for instance:
- Cataracts can also be classified by their location:
- Posterior (due to steroid use)
- Common senile (cataract related to aging)
Cataracts occurring at birth or present very early in life (during the first year of life) are medically termed as congenital or infantile cataracts. These cataracts need quick surgical correction otherwise they may restrict the vision in the affected eye from developing normally.
When the central portion of the lens is largely affected (this is the most common situation), these are called nuclear cataracts.
The outer part of the lens is called the lens cortex, and when opacities are most evident in this region, the cataracts are termed as cortical cataracts.
There is an even more specific change that sometimes takes place. When the opacity develops immediately next to the lens capsule, either by the anterior, or more commonly the posterior portion of the capsule it is called subcapsular cataracts.
Unlike most cataracts, posterior subcapsular cataracts can develop rather rapidly and affect vision all of a sudden unlike nuclear or cortical cataracts.
Exams and Tests
To locate a cataract, the eye-care provider examines your lens. A complete eye examination typically includes the following:
Visual acuity test
An eye chart test is used to evaluate your reading and distance vision.
Your eye specialist should decide if glasses would improve your vision.
Potential acuity testing
This helps the ophthalmologist to have an idea of what changes may occur to your vision after the removal of the cataract. Consider this as the eye’s vision potential if the cataract was not present.
Contrast sensitivity testing
This checks your ability to distinguish different shades of gray, which is often limited by cataracts.
It is a standard test to examine fluid pressure inside the eye (Increased pressure may be an indicative of glaucoma.)
The pupil is made enlarged by applying eye drops so that the ophthalmologist can further examine the lens and retina easily. This is important to determine if there are other conditions which may ultimately limit your vision besides cataracts.
There are three basic techniques for cataract surgery.
|Extracapsular cataract surgery||
|Intracapsular cataract surgery||
Although there is no scientifically proven prevention, some measures can be taken to check other eye diseases that can cause cataract and limiting exposure to factors that encourage cataracts.
Using sunglasses during the day might decrease your chances of developing cataracts or developing problems with the retina. Some sunglasses are designed to filter out UV light, limiting exposure to harmful UV radiation and might delay the formation of cataracts.
Although some people take vitamins, minerals, and herbal extracts to decrease cataract formation no scientific data reveal that these remedies are helpful. No topical or oral medications or supplements are found to reduce the chance of developing cataracts.
Just as a healthy lifestyle helps prevent other diseases in the body it also helps prevent cataract. Follow a proper diet, exercise regularly and take rest. Avoid smoking.
If you are suffering from diabetes, tight blood-sugar control can decelerate the otherwise accelerated development of cataracts.