Fig. 2. Retinitis pigmentosa. A. Advanced field loss showing dense annular defects. Deficits start in the 20° to 30° middle zone (as compared with Bjerrum's zone defects in glaucoma) and proceed toward fixation and outward toward the periphery. Central fixation is relatively spared, producing “gun-barrel fields.” B. The pseudobitemporal field defects of sector retinitis pigmentosa. Unlike chiasmal interference, the defects cross the vertical meridian. C. Left fundus of patient with nasal-sector retinitis pigmentosa.