Vitreous seed classification is predictive of response to intravitreal chemotherapy

This retrospective study evaluated outcomes of retinoblastoma treated with intravitreal melphalan as salvage for vitreous seeding.

Study design

The retrospective review included 28 eyes of 25 patients who were treated at Children's Hospital Los Angeles over a 5-year period. All patients received systemic intravenous chemotherapy followed by intravitreal melphalan as salvage treatment for persistent or recurrent vitreous seeding.

Outcomes

Overall, intravitreal chemotherapy was very successful at treating all types of vitreous seeds (dust, spheres, cloud). Clouds required the most injections and took more time to regress than dust or spheres. However, spheres were more likely to recur. There was 100% regression of vitreous seeds after intravitreal melphalan, and no eye was treated with radiation or enucleated for seeding.

Of the 28 treated eyes, the overall globe salvage rate was 68%. Nine eyes were eventually enucleated: 6 eyes because of massive recurrences or recurrences near the optic nerve that were not amenable to local therapy; and 3 from development persistent retinal detachment or neovascular glaucoma with very poor visual prognosis.

Limitations

This study excludes patients who received intra-arterial chemotherapy, yet included those who received intravenous chemotherapy. Therefore, the size of the study is very low for a 5-year period. Also, follow-up data was limited to a small cohort, as a third of these eyes were enucleated.

Clinical significance

This study found that the number of injections and required dose of intravitreal melphalan is dependent on the class of retinoblastoma seed, regardless of primary therapy. Anticipating that patients with clouds may require more injections allows for better counseling of families with children who are undergoing intravitreal chemotherapy.