38 CFR 4.76a: a Computation of average concentric contraction of visual fields.

Table III—Normal Visual Field Extent at 8 Principal Meridians

Meridian Normal degrees

Temporally 85

Down temporally 85

Down 65

Down nasally 50

Nasally 60

Up nasally 55

Up 45

Up temporally 55

Total 500

Example of computation of concentric contraction under the schedule with abnormal findings taken from Figure 1.

Loss Degrees

Temporally 55

Down temporally 55

Down 45

Down nasally 30

Nasally 40

Up nasally 35

Up 25

Up temporally 35

Total loss 320

Remaining field 500° minus 320° = 180°. 180° ÷ 8 = 221⁄2° average concentric contraction.