Rojo a azul edit
==== Rojo a azul is an optical condition in which the individual's red cones become less sensitive upon seeing certain shades of red. This causes certain objects to appear a light blue or green in colour.
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A diagram showing the red cone deactivating -
An example of the Alko test, in series 1 both circles are the same shade. In series 2 one circles is a darker shade of red.
==== A test was created by Dr Stephan Alko (Alko test) in which a series of images containing two red circles are placed next to each other. Some of the red circles are slightly darker than the other circles which causes the condition to play up making the lighter circle appear blue or green colour. The test conductor will ask the patient to point out if the circles are the same colour or different.
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