We measured the electroretinogram to determine whether ocular toxicity exists in men taking oral fenretinide, 100 mg daily, for prevention of adenocarcinoma of the prostate. Male subjects at an increased risk for prostate cancer were recruited as volunteers. Fenretinide treatment took place over 1 year with a regimen of 100 mg/day for 25 days with 3 day hiatus intervals. Baseline testing included the electroretinogram Ishihara plates, and the Farnsworth-Munsell D-15 test. Subsequent electroretinographic testing was conducted at 4, 8, 12 and 18 months. Thirteen of 14 subjects maintained normal age-matched electroretinographic responses 6 months after fenretinide treatment. Of these 13 subjects, six showed slight decreases, within 1 standard deviation of the normal mean. Two subjects showed a slight gradual decline of rod-mediated a-wave amplitudes, while b-wave amplitudes were steady. One subject, who had glaucoma, unilaterally fell below normal. After treatment ended, all of the 13 subjects had electroretinographic responses at their respective baseline levels. The subject whose responses fell and remained below 1 standard deviation showed an overall decline in responses and, on follow-up, was diagnosed as having branch retinal vein occlusion, which most likely is the main contributor to the decrease in electroretinographic responses. Our results indicate that men taking 100 mg of oral fenretinide per day for 1 year, with a 3 day hiatus each month, do not show toxicity -induced retinal dysfunction, as measured by the electroretinogram.
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