What is Colour Blindness?
At Zacks Eye Clinic in central London our Optometrists can test for colour vision deficiency or ‘colour blindness’ and provide advice on treatment with Chromagen lenses. Chromagen lens filters work by changing the wavelength of each colour going into one or both eyes, which enhances colour perception and colour discrimination. They can be worn discretely as soft contact lenses or made up as glasses.
Colour vision deficiency occurs when the cells in the retina (the nerve tissue which lines the back of the eye) fail to function normally. Colour vision deficiency is often known as colour blindness. However, true colour blindness is when you can see no colour whatsoever and is rare.
Having colour vision deficiency means you struggle to see colours the same way most people do. You may also have difficulty distinguishing between two different colours. Sometimes it’s difficult to know when you have colour vision deficiency, as there are no obvious or physical symptoms.
Colour vision deficiency affects approximately one in 20 men, and is far less common in women, with only one in 200 women affected. In most cases the condition is inherited, although you can develop a colour deficiency as a result of a pre-existing condition or as a side effect of a medicine you may be taking.
- Red-green deficiency is the most frequently diagnosed deficiency. People with this condition can’t distinguish certain shades of red and green. They are either deficient in long wavelength cones (protanopia) or medium wavelength cones (deuteranopia) which is most common.
- Blue-yellow deficiency arising form a deficiency in the short wavelength cones (tritanopia) is rare. This condition makes it difficult to distinguish between blue and green. Yellow can appear as a pale grey or purple.
- Total colour blindness (achromatopsia) is the rarest of the three. In this condition, no colours can be detected because none of the cone cells function normally and everything is seen in shades of black, white and grey. People with this condition have poor sight and are extremely sensitive to light.
