This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy, Subject name: Ophthalmology
[{'content': 'How many diopters does Pin hole test neutralize? \nSelect and explain. \nA. ID, B. 2D, C. 3D, D. 4D', 'role': 'user'}, {'content': 'Answer: C \nExplanation: ANSWER: (C) 3DREF: Oxford American Handbook of Ophthalmology By James Tsai Pg 7, Ophthalmology at a glance by J.Olver Ch 8The pinhole (stenopeic slit upto 1.2 mm) can neutralize upto 3 Dioptres of refractive error.It is a useful method of finding out if the patient is suffering from refractive errors. If the vision improves with a pinhole test, it means that the patient has a refractive error. See the diagram below:In emmetropia every point in an object of regard is brought to point focus on the retina and the sum of all the points yields a clear image, i.e. point-to-point correspondenceIf there is a refractive error present, a blur circle is formed on the retina, which is dependent on the size of their pupil (smaller pupil = smaller blur circle)When a pinhole aperture is placed in front of the eye, it acts as an artificial small pupil and the size of the blur circle is abolished/reduced, producing a clearer image', 'role': 'assistant'}]