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Causes of cataract

The natural lens of the eye is crystalline and transparent to allow unobstructed passage of light and enable vision at different distances by its ability to change shape. It becomes more convex for near vision. The eye lens can get opacities in it called a cataract. Worldwide, cataract is one of the leading causes of blindness in persons over 60 years of age, which has significant socioeconomic consequences. The cost implications to health services is a heavy burden, especially for developing countries. To date, the only real treatment of cataract is cataract surgery, although in the future scientists hope to have ways of preventing or reversing cataract. In many countries and even in Great Britain there are insufficient surgical facilities to manage all of our population with cataract in a timely fashion. In this blog post, I am looking much more closely at the various risk factors for the development of cataract and asking whether you and I can currently do something to prevent or slow down our onset of cataract.  

What are the causes of cataract?

We can classify cataract as having genetic risk factors, ageing risk factors, and can occur with systemic disease, nutritional and trace metal deficiencies, smoking and oxidative stress. There is traumatic cataract and complicated inflammatory cataract. There is also the metabolic diabetic and galactosaemia cataract, and a toxic cataract from drug and alcohol abuse. There is a radiation cataract from ultraviolet and electromagnetic waves. All of these categories are implicated as risk factors in the development of cataract.  Therefore, instantly by reading this list, you know that there are simple things you can do to cut down your risk of cataract.

  • You can look very carefully at your family to see if you have genetic factors.
  • You will want to try and slow down the onset of your hereditary cataract by avoiding other risk factors such as developing systemic diseases, by avoiding smoking, and by making sure that you have nutritional and trace metal supplements, and preventing eye trauma and dehydration.  
  • If you have inflammatory eye disease such as uveitis, you should get this treated rapidly.
  • You should have a healthy low sugar or sugar-free diet to try and avoid developing diabetes, avoid toxic drugs and drinking too much alcohol and avoid excessive exposure to ultraviolet radiation.  

South East Asia and Africa are parts of the world where cataract is endemic in young adults and older adults. Cataract care creates an enormous economic burden on countries, which already have high levels of poverty.  Let’s look more closely at some of the causes of cataract.  

Are there some people more prone to cataract?

A congenital cataract is hereditary and can occur with congenital eye malformation such as microphthalmia, aniridia, inherited retinal degeneration and other multi-system genetic disorders such as chromosome abnormalities, Lowe syndrome and neurofibromatosis. Congenial cataract can also have maternal or foetal risk factors and not just the above genetic factors. If a mother has had malnutrition or severe dehydration during pregnancy, or a maternal infection such as rubella toxoplasmosis, or cytomegalovirus, there is an associated higher risk of congenital cataract. If the mother has had an endocrine disturbance or has been abusing alcohol or drugs, for instance, thalidomide or corticosteroids, or has had exposure to radiation during pregnancy, this increases the risk of cataract in their offspring. Intrauterine hypoxia in the last trimester of gestation, myotonic dystrophy, congenital ichthyosis are all factors that can cause cataract in infants and, of course, researchers have associated galactosaemia with the early development of bilateral cataracts in young adults. Women have a greater incidence of most types of cataract than men probably due to the lack of oestrogen in the post-menopausal years. Research suggests that there are possible protective effects of oestrogen treatment against cataract development.  Race and ethnicity can have a role, and this may be genetic, or it may be environmental. African-Americans and Hispanic Americans appear to have nearly twice the risk of developing cataract than Caucasians. The increased incidence in these populations could also be due to a higher rate of diabetes and the lack of early treatment. The most common cause of cataract remains age-related or senile cataract which is a cataract occurring in people over the age of 50 years and unrelated to any other reason such as mechanical, chemical, endocrine or radiation, although can be aggravated by environmental and systemic factors. It is slowly progressive until it is quite severe and we frequently encounter it in the elderly.  This type of cataract is due to the breakdown and aggregation of protein within the lens with damage to the lens fibre cell membranes. Oxidative damage, elevated calcium and abnormal lens epithelial cell migration all contribute to the development of senile cataract.  Dehydration can contribute to worsening of senile cataract. Hypertension and smoking, especially in the presence of diabetes, can help cause cataract. If you would like to know more about cataract and think you may have one, you should book to see Ms Laura Crawley or Mr Jaheed Khan, the cataract specialists at Clinica London.

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