Table 2. Change in standard automated perimetry (SAP) visual field index (VFI) corresponding to different amounts of change in estimated retinal ganglion cell (RGC) counts at different stages of disease.

Stage of disease		Change in VFI (%) for a change of:
VFI (%)	Estimated RGC count (cells)	10,000 RGCs	100,000 RGCs
100	1,150,000	0.03	0.3
95	650,000	0.2	3.0
90	510,000	0.6	7.2
80	380,000	1.1	13.5
60	240,000	1.9	19.8
40	140,000	2.3	22.1

VFI = visual field index.

RGC = retinal ganglion cell.