Classification of Vitreous Seeds in Retinoblastoma: Correlations with Patient, Tumor, and Treatment Characteristics.

PURPOSE: To evaluate the patient, disease, and tumor characteristics of the 3 morphologically distinct groups of vitreous seeds in retinoblastoma presenting for treatment with ophthalmic artery chemosurgery (OAC): dust (class 1), spheres (class 2), and clouds (class 3) in primary and recurrent vitreous seeds.

DESIGN: Retrospective cohort study of patients treated for vitreous seeds at Memorial Sloan Kettering Cancer Center between May 2006 and March 2015.

PARTICIPANTS: A total of 135 eyes with active vitreous seeds, presenting for primary treatment with OAC or with recurrent vitreous disease.

METHODS: Vitreous seeds were classified into 3 groups: dust, spheres, and clouds. Indirect ophthalmoscopy, fundus photography, ultrasonography, and ultrasonic biomicroscopy were used to locate and evaluate the extent of retinal and vitreous disease. Patient and disease characteristics (age, laterality of disease, treatment status) were compared among classification groups. A 2-tailed Fisher exact test and paired Student t test were used for statistical analysis.

MAIN OUTCOME MEASURES: Age of patient, laterality of disease, location of retinal disease, extent of vitreous disease, and treatment status.

RESULTS: Primary treated disease: Patients with eyes containing class 3 (cloud) vitreous seeds were significantly older than patients with class 1 or 2 seeds (P < 0.05). The median age of patients with class 1, 2, and 3 seeds was 11, 15.5, and 32 months, respectively. Eyes containing class 3 seeds were significantly more likely to occur in the equator-ora region of the fundus (P < 0.0001), in a diffuse pattern (P < 0.0001), and in patients with unilateral disease (P < 0.05), compared with class 1 and 2 seeds. Recurrent disease: Recurrent vitreous seeds were significantly more common to class 2 (P < 0.05), occurring in a diffuse pattern (P = 0.01) and in patients with bilateral disease (P < 0.001).

CONCLUSIONS: The 3 classes of vitreous seeds have distinct clinical characteristics associated with the age of patient, laterality of disease, and extent and location of tumor-producing seeds. Furthermore, recurrent vitreous seeds appear to have a unique clinical profile compared with seeds receiving primary treatment.