This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Primary Open-Angle Glaucoma and Related Conditions, Subject name: Ophthalmology
Earliest field defect in primary open angle glaucoma: 
Select and explain. 
A. Reidel's scotoma, B. Scotoma in Bjerrumns field, C. Arcuate scotoma, D. Nasal spur
B: Scotoma in Bjerrumns field
Answer: B: Scotoma in Bjerrumns field 
Explanation: Ans. is 'b' i.e. Scotoma in Bjerrum's field Visual field defects in Glaucoma:Baring of blind spotScotoma in Bjerrum's fieldArcuate scotomaSeidel's scotomaRing or double arcuate scotoma.Roenne's central nasal step.Advanced field defect:At the last only a small island of central vision {tubular vision) and an accompanying temporal island are left.The temporal island is usually extinguished before the central island although occasionally this sequence is reversed.