Toxic effect of fluorouracil on the rabbit retina

We conducted electrophysiologic tests of the toxic effects of fluorouracil on 26 albino rabbit eyes. Fluorouracil concentrations of 10(-7) g/ml, 10(-6) g/ml, and 10(-5) g/ml produced no significant changes in the b-wave amplitudes of the electroretinogram. A concentration of 10(-4) g/ml, however, reduced the b-wave amplitude to 62% +/- 7.3% of the original value after 60 minutes. A concentration of 10(-3) g/ml decreased the value even further, to 41% +/- 12% of the original value. At this concentration the a-wave appeared to be enhanced, probably because the ascending phase of the b-wave was delayed. A concentration of 5 X 10(-3 g/ml resulted in disappearance of the b-wave within approximately three minutes, but removal of the test solution and replacement with a fluorouracil-free medium produced recovery of the b-wave amplitude to 89% +/- 9.9% of the original value within 55 minutes.