This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Retina, Subject name: Ophthalmology
Phenomenon in which all colors are seen as grey due to decreased sensitivity of cones is called 
Select and explain. 
A. Stile Crawford effect, B. Purkinje shift, C. Dark adaptation, D. Color blindness
B: Purkinje shift
Answer: B: Purkinje shift 
Explanation: Phenomenon in which all colors are seen as grey due to decreased sensitivity of cones is called Purkinje shift. The Stiles-Crawford effect is the phenomenon where light entering the eye near the edge of the pupil produces a lower photoreceptor response compared to light of equal intensity entering near the center of the pupil.