Presentation by International Classification of Retinoblastoma grade of disease (not available for one patient)
| Stage* | N | Mean age at presentation/months (SD) | Median age | Laterality of disease (n)† | Median lag /months | |
| Unilateral | Bilateral | |||||
| A | 0 | – | – | – | – | – |
| B | 1 | – | 4.3 | 1 | – | 0.2 |
| C | 8 | 24.8 (16.0) | 27 | 6 | 1 | 1.55 |
| D | 35 | 21.5 (26.8) | 13.8 | 13 | 23 | 1.13 |
| E | 48 | 20.6 (20.7) | 12.1 | 13 | 35 | 1.78 |
*Information on laterality for one stage ‘C’ eye was unavailable.
†In bilateral cases this represents the stage of the more advanced eye.