Coding and registration status for screening
| Red | Never screened (known to DESP) |
| Amber | Overdue screening (known to DESP) |
| Green | Screened within previous 12 months (known to DESP) |
| Not registered | Unknown to DESP and possibly undiagnosed diabetes |
| No action needed | Known to DESP and within specialist ophthalmology clinics / opted out |
DESP = Birmingham, Solihull and Black Country Diabetic Eye Screening Programme.