[Study on conservative treatment of retinoblastoma--effect of intravitreal injection of melphalan on the rabbit retina].

Effects of an intravitreal injection of melphalan on the electroretinogram and on the retinal structure were studied in albino rabbits to establish the non-toxic dose for its intravitreal use. The a-wave, the b-wave, the c-wave, the oscillatory potential and the retinal structure remained unchanged after 10-micrograms injection, but moderately changed after 20-micrograms injection and greatly deteriorated after 90-micrograms injection. A 10-micrograms injection is equal to an intravitreal concentration of about 5.9 micrograms/ml, if evenly diffused in the rabbit vitreous. Considering that colony formation of in vitro retinoblastoma cells is completely suppressed by melphalan at 4 micrograms/ml concentration, an intravitreal application of melphalan could be used as a non-surgical treatment for retinoblastoma.