What isocoricas pupil is incorrectly written and should be written as 'isocoricas pupils' being its meaning: They are those that are the same size in both eyes. The pupil is the dark central area of the iris of the human eye which you can shrink or expand according to the amount of light, which serves as a window to the retina to see the physical reality that interprets the brain. Isochoric is a medical term derived from the Greek ( isos ise ison: equal and choros chorou: space, extension, ) This term is not in the RAE dictionary.