Long-term effects of fenretinide on retinal function

The long-term effects of the synthetic retinoid fenretinide (4-HPR) on retinal function were studied by electroretinogram (ERG) in 24 women treated for a median of 30.5 months and in 18 untreated controls belonging to a phase III intervention trial. The six outcome measures were: a wave implicit time, peak-to-peak amplitude and implicit time of b wave following both cone stimulation and maximal cone-rod stimulation in the dark-adapted eye. Multivariate analysis of covariance was applied to evaluate the joint effect on the whole set of ERG measures taking into account their inter-relationship. Predictive factors with a significant effect on ERG measures were: (1) a qualitative interaction between age and treatment duration and (2) the squared (parabolic) function of plasma retinol. Individually, the b wave implicit time following cone stimulation was the only ERG measure significantly influenced by the predictors, indicating a primary effect of 4-HPR on retinal photoreceptor sensitivity without significant alterations of the inner nuclear layer. Thus, in contrast to previous reports at higher dose, administration of 4-HPR at 200 mg/day seems to exert subtle alterations of retinal function as measured by ERG.