RESUMO
BACKGROUND: The use of drugs of abuse--e.g., cocaine--during pregnancy has been associated with abnormalities of the visual system. The authors studied the effects of prenatal exposure to drugs of abuse, especially cocaine, on the vascular system of the retina in newborn infants and in an experimental model in the rat. METHODS: The animal study was conducted in pregnant Wistar rats injected subcutaneously with cocaine hydrochloride (60 mg/kg body weight/day) from gestation days 8 to 22. Male offspring were killed at postnatal days 7, 14, and 30 and perfused with fixative, and the retinas were dissected and processed for microscopic observation. The ophthalmologic observations were conducted in a population of newborn infants born to women who abused many drugs during pregnancy and in a control group of women with no history of illicit drug use. RESULTS: Vascular disruptive lesions were seen after prenatal exposure to cocaine in the rat: round intraretinal hemorrhages, ischemic and hypoperfused areas located at the temporal part and often extending from the posterior pole to the periphery of the retina. The ophthalmologic observation of the newborns showed a higher incidence of vascular disruptive lesions in infants in whom exposure to drugs of abuse was affirmative during pregnancy. In the cases in which cocaine consumption was reported, they consisted in blot full-thickness hemorrhages with rounded domed contours suggestive of venous occlusion and retinal ischemia, very similar to the lesions seen in the animal model. These hemorrhagic lesions, morphologically similar to neonatal retinal hemorrhages, had a higher incidence than in controls; they also took longer to resolve when compared with the reabsorption time of the neonatal hemorrhages due to birth trauma and the hemorrhagic lesions in newborns of mothers in whom consumption of other drugs--but not cocaine--were reported. CONCLUSION: A topographic and morphologic parallelism can be established between the retinal vascular alterations found in humans consuming cocaine and in the animal model of prenatal exposure to this drug of abuse; although findings from animal studies may be difficult to apply directly to humans, these data strongly support that cocaine can be a causal factor for the occurrence of retinal vascular disruption in newborns.
