This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
Earliest field defect in primary open angle glaucoma – 
Select and explain. 
A. Riedel's scotoma, B. Scotoma in Bjerrums field, C. Arcuate scotoma, D. Nasal spur
B: Scotoma in Bjerrums field
Answer: B: Scotoma in Bjerrums field 
Explanation: Paracentral scotoma appears either below or above the blind spot in Bjerrum's area.