Effects of embryonic exposure to ethanol on zebrafish visual function.

Across a variety of species, including humans, it has been shown that embryos exposed to ethanol display eye abnormalities as well as deficiencies in visual physiology and behavior. The purpose of this study was to examine the effects of embryonic exposure to ethanol on visual function in zebrafish. Visual function was assessed physiologically, via electroretinogram (ERG) recordings, and behaviorally, by measuring visual acuity with the optomotor response. Zebrafish larvae were exposed to 1.5% ethanol at various times during development, including the period of maximal eye development. The results show that ethanol effects on visual function were most pronounced when exposure occurred during eye development. ERG recordings from ethanol-exposed larvae differed from normal subjects both in shape of the response waveform and in visual thresholds under both light and dark adaptation; the differences were more pronounced under lower levels of adaptation. Also, ethanol-exposed larvae displayed lower visual acuity as determined from the optomotor response. These results indicate embryonic ethanol exposure affects visual function particularly when exposure occurs during eye development. In addition, these findings illustrate the usefulness of the zebrafish as a viable animal model for studying Fetal Alcohol Syndrome (FAS).