Purpose: To determine when patients with a family history of retinoblastoma and previously normal eye exam develop intraocular disease, and where the new retinoblastoma tumors occur.
Methods: A retrospective chart review of retinoblastoma patients.
Results: Sixty-two percent of the first eyes (eyes having a previously normal examination) were diagnosed with retinoblastoma by 6 months of age, 90% by 12 months and 100% by 28 months. For the second eye, 27% were identified by 6 months, 64% by 12 months, 91% by 30 months and 100% by 44 months. The younger the age at initial diagnosis of retinoblastoma, the greater the likelihood that tumors will initially be found in the posterior pole. Macular tumors were diagnosed very early (mean 4 months) and once a retinoblastoma focus had appeared in one eye no new tumors developed in the macula of either eye.
Conclusion: The timing, location, and number of new retinoblastoma tumors follows a predictable pattern.