| POAG Stage | Defect Score Interval (in decibels) |
| No POAG | No visual field defect |
| Early | −0.01 to −6.00 dB |
| Moderate | −6.01 to −12.00 dB |
| Advanced | −12.01 to −20.00 dB |
| Severe Visual Impairment | −20.01dB or worse |