OPTO
| Date | Clue |
|---|---|
| 2018-08-10 | Prefix with -metry |
| 2017-07-11 | Vision: Prefix |
| 2012-06-19 | Vision: Prefix |
| 2012-06-07 | Vision: Prefix |
| 2010-02-13 | Prefix with -metry |
| 2010-02-11 | Vision: Prefix |
| 2006-04-28 | Vision: Prefix |
| 2006-01-14 | Vision: Prefix |
| 2002-12-06 | Vision: Prefix |