• Question: Are most eye conditions hereditary? What are the chances of a child getting it if one parent has an eye condition and the other does not?

    Asked by roisin to Enda, Jean, Tim on 22 Nov 2012.
    • Photo: Enda O'Connell

      Enda O'Connell answered on 22 Nov 2012:

      Hi Roisin,

      According to the World Health Organisation “there are no global statistics which let us know the extent of the burden of visual impairment from genetic causes, it does seem that genetic eye pathology represents a significant percentage of the causes of blindness in industrialized countries.”

      In poorer countries a lot of eye disease is caused by infection, such as Trachoma (caused by the bacteria Chlamydia trachomatis) which affects over 20 million people, over 1 million of whom are blind; or River Blindness (caused by the parasite Onchocerca volvulus which is spread by blackflies).

      In industrialised countries like Ireland, eye infections are much rarer, so the eye conditions we experience, such as cataracts, glaucoma and macular degeneration, are more linked to ageing as we live longer. Some forms of glaucoma are linked to our genes, with certain types more frequent in Africa or Asia.

      Eye conditions like short-sightedness (myopia) which may require you to wear glasses, are however linked to whether your parents are short-sighted. There are a range of figures as to what the exact chances are, but if you have two short-sighted parents you have a better chance of being short-sighted than if you have one or none. In some parts of Asia, myopia is the norm with over 80% of people in Singapore having short-sightedness, while the figure is only about 10 or 20% in Africa.

    • Photo: Jean Bourke

      Jean Bourke answered on 23 Nov 2012:

      Whether or not you get something your parents have is quite a difficult question to answer. There are certain things that are purely genetic (such as huntington’s disease) but most things are based on both nature (genetic) and nurture (environmental).

      If one of your parents has an eye condition it may not be for genetic reasons, it could have resulted from a physical injury or illness or a nutrient deficiency at some point in their lives. Diabetes for example can effect vision as it can damage the optic nerve which carries signals between your eyes and brain (one of the many reason diabetes has to be carefully managed). Similarly, just because your parents have perfect vision, does not mean you will too.

      Most human characteristic are what we call multifactorial which means many genetic factors are involved and you are made of all your genes and also are a product of your environment.