Cataract is the clouding of the normal clear lens of the eye which causes a decrease in vision. It often develop slowly and can affect one or both eyes. Due to the clouding eye lens, people living with cataract experience difficulties in reading, driving, seeing expressions on people's face and even seeing things from little distance this is because seeing through cloudy eye lenses is like looking through a frosty or fogged-up window.
Cataracts are most commonly due to aging, but may also occur due to trauma, radiation exposure, congenital or occur following eye surgery for other problems. Risk factors of cataracts include: diabetes, smoking tobacco, prolonged exposure to sunlight, and alcohol.
Cataract is the first leading cause of blindness worldwide, followed by glaucoma.
Age-related cataracts are responsible for 51% (20 million) of world blindness. Globally, cataracts cause moderate to severe disability in 53.8 million (2004), 52.2 million of whom are in low and middle income countries.
In countries where surgical services are inadequate, cataracts remain the leading cause of blindness. Even where surgical services are available, low vision associated with cataracts may still be prevalent as a result of long waits for, and barriers to, surgery, such as cost, lack of information and transportation problems. Cataracts is responsible for nearly 60% of blindness in parts of Africa and South America. In the eastern Mediterranean region, cataracts are responsible for over 51% of blindness.
Cataracts affect nearly 22 million Americans age 40 and older. By age 80, more than half of all Americans have cataracts.
Cataracts are of two classes; age-related cataracts and congenital cataracts. Age-related cataracts are of four types; nuclear sclerosis, cortical, and posterior subcapsular cataracts.
CAUSES OF CATARACTS
The lens of the eye functions like a camera lens, focusing light onto the retina for clear vision. It also adjusts the eye's focus, letting us see things clearly both close and far away.
It's mostly made of water and protein. The protein is arranged in a way that keeps the lens clear and lets light pass through it.
As one gets older, some of the protein may clump together and begin to cloud area of the lens. Over time, it grow bigger and cloud more of the lens, making it difficulty to see.
What causes the protein to clump which results to lens clouding (cataracts) as one gets older is not clearly known. Researchers worldwide have indicated factors that may cause cataracts or cause cataracts to develop.
Cataracts may develop dut to the following factors: age, genetic disorders, taruma, medications, radiations, skin diseases
1. Age
Older people are more prone to cataracts, because lens proteins denature and degrade over time, and this process is accelerated by diseases such as diabetes mellitus and hypertension. Environmental factors, including toxins, radiation, and ultraviolet light, have cumulative effects, which are worsened by the loss of protective and restorative mechanisms due to alterations in gene expression and chemical processes within the eye.
2. Trauma
In severe blunt trauma, or injuries which penetrate the eye, the capsule in which the lens sits can be damaged. This allows water from other parts of the eye to rapidly enter the lens leading to swelling and then whitening, obstructing light from reaching the retina at the back of the eye.
3. Radiation
Ultraviolet light, specifically UVB, has been shown to cause cataracts. Microwave radiation has also been found to cause cataracts. The mechanism is unclear, but may include changes in heat-sensitive enzymes that normally protect cell proteins in the lens. Another possible mechanism is direct damage to the lens from pressure waves induced in the aqueous humor. Cataracts have also been associated with ionizing radiation such as X-rays.
4. Skin disease
The skin and the lens have the same embryological origin, hence can be affected by similar diseases. For instance those with atopic dermatitis and eczema occasionally develop shield ulcers cataracts.
5. Genetics Disorder
Certain genetic disorders can lead to development of cataracts. Examples of chromosome abnormalities associated with cataracts include: 1q21.1 deletion syndrome, cri-du-chat syndrome, Down syndrome, Patau's syndrome, trisomy 18 (Edward's syndrome), and Turner's syndrome. Examples of single-gene disorder include Alport's syndrome, Conradi's syndrome, myotonic dystrophy, and oculocerebrorenal syndrome or Lowe syndrome.
6. Medication
Certain medication such as corticosteroids, can induce cataract development. Researchers from the University of Waterloo, Canada, reported in the journal Optometry and Vision Science that people who take statins have a higher risk of developing age-related cataracts. Miotics and triparanol may also increase the risk.
SYMPTOMS OF CATARACTS
Symptoms of cataracts include:
Cloudy, blurry, fuzzy, foggy or filmy vision
A noticeable cloudiness in the pupil
Increased glare from lights eg: from headlights when driving at night
A decrease in distance vision but an improvement in near vision.
Double vision (diplopia)
Frequent changes in eye prescriptions
Impairment of colour vision
Poor vision in sunlight.
< /script>TREATMENT OF CATARACTS
Surgery
Surgery is one of the effective ways to correct cataracts. But prescripted glasses, better lighting or effective sunglasses can be used to improve the early symptoms.
Cataract surgery involves removal of the cataract-damaged lens and replacing it with a clear plastic lens known as an intraocular lens (IOL). The eye is carefully measured before surgery so that the appropriate size of intraocular lensof to be used can be selected. The aim of surgery is to restore vision (particularly distance vision) as much as possible.
Surgery involves making a small incision in the front of the eye, through which the old lens is removed and a new intraocular lens is inserted. The incisions are usually made using a hand-held microscopic blade but, in recent times, laser cataract surgery has allowed computer-guided, bladeless incisions to be made.
Two techniques for the surgical treatment of cataracts are:
Phacoemulsification surgery, and
Extracapsular surgery.
REFERENCE:
https://en.m.wikipedia.org/wiki/Cataract
https://www.southerncross.co.nz/AboutTheGroup/HealthResources/MedicalLibrary/tabid/178/vw/1/ItemID/202/Cataracts-causes-symptoms-treatment-surgery.aspx
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