###Rationale: 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.

###Answer: OPTION B IS CORRECT.
###Question: Earliest field defect in primary open angle glaucoma:
###Options:
A. Reidel's scotoma
B. Scotoma in Bjerrumns field
C. Arcuate scotoma
D. Nasal spur
