Colour Blindness

Colour Blindness

Subject: Science & Tech

Section: Basic science

Context- The Supreme Court has directed the Film and Television Institute of India (FTII) not to exclude candidates suffering from colour blindness from its courses on film making and editing and asked it to make changes to its curriculum instead.

Concept-

What is colour blindness?

• Colour blindness, also known as colour deficiency, is the inability to see colours in the normal way.
• Colour blind individuals often cannot distinguish between certain colours— usually greens and reds, and sometimes blues as well.
• Two types of cells in the retina detect light — the “rods”, which distinguish between light and dark, and the “cones” that detect colour. There are three types of cones that see colour — red, green, and blue — and our brains use the information from these cells to perceive colour.
• Colour blindness can be the result of the absence of one or more of these cone cells, or their failure to work properly. In a situation where all three cone cells are present but one of them is malfunctioning, mild colour blindness may occur.
• Colour blindness may be of different kinds and degrees. Mildly colour blind people often see all colours properly only when the light is good; there are others who cannot tell one colour apart from the another no matter how good the light is.
• In the most severe kind of colour blindness, vision is black-and-white, that is, everything appears as a shade of grey. This is not very common.
• Colour blindness cannot as yet be treated or reversed. However, it can be corrected to some extent by wearing special contact lenses or colour filter glasses. There is some research that suggests gene replacement therapy can help modify the condition.

What causes colour blindness:

• Most colour blind people are born with the condition (congenital colour blindness), but some can develop it later in life.
• Congenital colour vision deficiencies are usually passed on genetically.
• A problem with colour vision that arises later in life could be the result of disease, trauma, or ingested toxins.
• If colour blindness arises out of disease, one eye may be affected differently from the other, and the difficulty could worsen over time.
• Medical conditions that may increase the risk of getting colour blindness include glaucoma, diabetes, Alzheimer’s, Parkinson’s, alcoholism, leukaemia, and sickle-cell anaemia.

Who is at risk?

• Men suffer from a higher incidence of colour blindness than women.
• Around the world, every tenth male is estimated to have some form of colour deficiency.
• Men of Northern European descent are considered to be especially vulnerable.