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
By pinhole visual acuity is neutralized till: 
Select and explain. 
A. 1 D, B. 2 D, C. 3D, D. 4D
C: 3D
Answer: C: 3D 
Explanation: Ans. (c) 3 DRef.: A.K. Khurana 6th ed. /578* By pinhole test visual acuity can be neutralized till 3 D. It can't accommodate more than that.* It is a test to distinguish a refractive error from organic disease.* A refractive error may, be corrected with glasses, whereas organic disease may signal the development of preventable blindness. If visual acuity is improved after pin hole test, the defect is refractive; if not, it is organic.# Pinhole improves vision: refractive error, peripheral cataract# Pinhole worsen vision: Macular diseases, central lens opacities# Vision static with pinhole: Amblyopia