Differential rates of visual field loss by initial severity of defects

Purpose. To examine whether the rate of progression of visual field loss varies by initial severity of field defects. Methods. A cohort of glaucoma patients were followed for up to 8 years with annual ' 1X30-2 Humphrey visual field tests Changes in the mean threshold level of the field and changes in the volume of scotomata were estimated over the foil' >w-up period for patients classified as having mild (mean threshold > 25 dB), moderate (15-25 dB) or severe (< 15 dB) field loss at baseline. Results. 187 eye: of 132 glaucoma patients with confirmed visual field loss were followed. In patie its with severe initial loss, mean threshold declined linearly by 2.4 dB over 8 yean. The scotoma volume increased by 6% in the 1st 3 years and by 48% in the subsequent years. In patients with moderate initial loss, mean threshold declined by l dB over the 1 st 4 years, and about 4 dB over subsequent years. Scotoma volume shrunk by 28% in the 1st 4 years, increased by 16% in the next 2 years, a id by 72% in the remaining 2 years. For those with mild initial loss, no change v 'as seen in the first 4 years, but there was a decline of 4 dB over the next four yean . Scotoma volume shrunk by 6% in the 1st 2 years, increased by 14% in the next 2 years, and by 70% in the remaining years. Conclusions. These data provide modt st evidence that the rate of progression differs by initial severity of field loss. Patients with the most severe initial loss had the slowest rates of progression.