Effects of fenretinide (4-HPR) on dark adaptation.

OBJECTIVES To assess the alterations in dark adaptation induced by low (200 mg/d) doses of fenretinide (4-HPR), to assess whether these effects were cumulative and whether they were reversible, and to attempt to elucidate the mechanism underlying the changes in night vision. DESIGN Case series. SETTING Outpatient eye clinic. PATIENTS Twenty-two women enrolled in a breast cancer chemoprevention trial, and 18 normal control subjects. INTERVENTION Measurements of absolute luminance thresholds during dark adaptation. MAIN OUTCOME MEASURES Parameters of an exponential model of the dark-adaptation function before, during, and after administration of fenretinide. RESULTS The most conspicuous effect of fenretinide on dark adaptation was a significant delay in the timing of the rod-cone break (P<.001). A minimal elevation of the final cone threshold was also observed. These effects were reversible after fenretinide therapy was discontinued and did not seem to be cumulative. An inverse relationship between delay of the rod-cone break and plasma retinol concentration was found. CONCLUSION The dose of fenretinide used in this study produced clearly measurable, but not severe, changes in night vision, which were rarely symptomatic.