Dr Imran Ansari
Colour vision snags among majority in UAE
Dubai, June 10, 2013
Significant colour vision defects were revealed in the vast majority of the Emirati population that was tested in a study that included locals with and without diabetes, according to a report.
Moorfields Eye Hospital Dubai, the first overseas branch of Moorfields Eye Hospital NHS Foundation Trust, has revealed some of the findings of its first UAE colour vision study, undertaken by specialists from the hospital.
The general causes of ‘colour blindness’ (colour vision defects) are well known but more research was needed to assess whether this UAE revelation is due to genetic or acquired factors (such as excessive exposure to sunlight or Vitamin D deficiency), the study said.
Dr Imran Ansari, an ophthalmologist at Moorfields Eye Hospital Dubai, said: “There are different forms of ‘colour blindness’ which may have a variety of long term lifestyle implications as there is no cure.”
“The condition may be acquired or inherited (congenital). It is usually classed as a mild disability and whilst it can be debilitating to some degree, there are also some situations where it can actually be an advantage, such as penetrating certain colour camouflages.
“Of course, there are some occupations in which ‘colour blindness’ is a distinct disadvantage, where recognising colour codes could be an important safety factor, such as when driving cars or flying aircraft, for example,” he added.
What is commonly referred to as ‘colour blindness’ is not blindness at all but rather a colour vision deficiency – an inability or decreased ability to see colour or perceive colour differences under normal lighting conditions, he explained.
The first scientific paper on colour ‘blindness’ was published by an English chemist - John Dalton - in 1798, when he realised that he was colour blind. The paper was titled ‘Extraordinary facts relating to the vision of colours’.
Colour blindness affects a significant number of people and especially isolated communities with a restricted gene pool. More than 95 per cent of all variations in human colour vision involve the red and green receptors in male eyes and it is very rare for males or females to be ‘blind’ to the blue end of the spectrum.
An Ishihara colour test consisting of a series of pictures of coloured spots is the test most often used to diagnose red–green colour deficiencies, with a shape or number embedded in the picture and which can be seen with normal colour vision but not with a colour defect.
The cause of colour blindness is now well known and understood and is related to a fault in the development of one or more sets of retinal ‘cones’ that perceive colour in light and transmit that information to the optic nerve. It is more common amongst men than women because it is linked to the genes, although eye or brain damage can also produce similar symptoms.
Colour blindness can be stationary or progressive in nature and can be linked to other eye conditions such as age related macular degeneration.
It can be total (much less common) or partial and there are two major types of colour blindness: difficulty distinguishing between red and green, difficulty distinguishing between blue and yellow. Around 8 per cent of males but only 0.5 per cent of females are colour blind in some way or another. – TradeArabia News Service
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