The pupils are two naturally present apertures in the iris, one in each eye, though they look to be placed centrally in fact they are slightly shifted medially. A gross shifted of pupil from its usual position is called corectopia. The normal pupil is circular, a distorted pupil is called dyscoria. The size of normal pupil at rest is 2 to 2.5 mm. A small pupil is called miotic pupil and the process is known as miosis. A large pupil at rest is called mydriatic pupil and the process of dilation of the pupil is called mydriasis. Miosis due to neurological and pharmacological causes are associated with spasm of accommodation, i.e. cyclotonia and mydriasis due to neurological causes and para-sympatholytic drugs is associated with abolished or reduced accommodation and, i.e. cycloplegia. A combination of neurological mydriasis and cycloplegia is called internal ophthalmoplegia. The term iridoplegia denotes absence of movement of the pupil to light and near.