Purpose: To investigate the toxic effects of perfusion of intravitreal melphalan during vitrectomy on the rabbit retina.
Methods: We performed electoretinography (ERG) in 18 eyes of 18 healthy albino rabbits before and after intraocular melphalan perfusion at concentrations of 5-, 10-, and 20-microg/ml during pars plana vitrectomy. Fellow eyes that underwent vitrectomy without melphalan served as controls. The histopathologic retinal changes were observed in both eyes of two rabbits from each group.
Results: In the 5-microg/ml perfusion group, the ERGs and histology showed no substantial changes compared with control fellow eyes during 28 days postoperatively. In the 10- and 20-microg/ml groups, the mean a-wave amplitude decreased to 52% and 31% respectively of the fellow eye; the mean b-wave amplitude decreased to 52% and 19% respectively. However, the peak implicit time of the a- and b-waves did not significantly differ in the 10- and 20-microg/ml groups during 28 days postoperatively. Histologic sections showed necrosis of the inner nuclear layer and thinning of the outer nuclear layer in the 10-microg/ml group. Loss of the outer nuclear layer and the photoreceptor layer and necrosis of the inner nuclear layer were observed in the 20-microg/ml group.
Conclusion: The intravitreal 5-microg/ml melphalan perfusion during vitrectomy appears to be nontoxic to the retina. This therapeutic modality might be a potential treatment for retinoblastoma with vitreous seeding.