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What are causes of cataracts?

As we age, some of the protein may clump together and start to cloud a small area of the lens. This is our understanding of the cause of an age-related cataract. Over time, the cataract may become denser or cloud more of the lens, making it more difficult to see through. A cataract is not a growth or tumor.


Because of the UV radiation, pollution, staring electronic screen for long hours, smoking and other different factors, the lens begins to harden and Presbyopia around 40 years old in general. In the age of 50 or above, the lens will be hardened and Presbyopia will gradually evolve into cataracts, which is caused by the degeneration of senile cataract, because about two long lens is affected by various factors in the same environment and normally happened in both eyes.

Secondary cataract

There are many causes of non age-related cataracts or secondary cataracts. Secondary cataracts are a result of similar changes to the protein of the lens, also resulting in visual blurring or visual loss.


(1) Traumatic cataract

Blunt or penetrating injury to the eye may cause secondary cataracts, either immediately after the injury or some weeks to years afterward. A cataract following an injury may appear and then not increase in density (be stationary) or be progressive. Eye surgery for other conditions can also cause cataracts. Excessive exposure to ionizing radiation (X-ray), infrared radiation (as in glass blowers), or ultraviolet radiation cause secondary cataracts.

(2) Complicated cataract

This type of cataract is determined by other things such as iritis, glaucoma, retinopathy and other eye diseases. Inflammatory disease of the eye, such as iritis or uveitis, may cause or accelerate the development of cataract in the involved eye.


(3) Metabolic cataracts

Unlike complicated cataract, this type of cataract is associated with other parts of the body. High blood pressure, high cholesterol and diabetes will uptake nutrients to the eye. When the lens lacks the necessary nutrients, they would gradually evolve into cataracts. Due to low metabolism, rate the lens is possible to turbidity, as the result, diseases such as galactosemia, congenital metabolic diseases, etc., can easily lead to cataracts. 


(4) Drug-induced cataract

There are many medications which, when taken over a long period of time, can cause secondary cataracts. The most common of these are oral corticosteroids, such as prednisone, which are used for a wide variety of medical conditions.


Congenital cataracts


Patients who develop cataracts in both eyes at an early age often have family members who have also developed cataracts prematurely, implying a genetic cause, even in the absence of a recognized underlying disease.


The term "congenital cataract" is used when a baby is born with any clouding of the lens. This may be present in one or both eyes, be stationary or be progressive. Causes include genetic disorders or intrauterine developmental disorders, both often associated with other physical abnormalities of the baby.

There are many genetic illnesses that are associated with the development of secondary cataracts. These include myotonic dystrophy, galactosemia, homocystinuria, Wilson's disease and Down syndrome, plus many others. Congenital infections with herpes simplex, rubella, toxoplasmosis, syphilis, and cytomegalic inclusion disease may also result in cataracts.

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