Visual functioning following prenatal exposure to organic solvents.
Published: 2004
Language: eng
Number of pages: 257
Description: Despite a large body of evidence demonstrating that the visual system is an important target for organic solvent toxicity in adults, little attention has been devoted to the visual functioning of children with prenatal solvent exposure. The aims of the current study were (1) to evaluate prospectively the impact of prenatal solvent exposure on selective aspects of infant visual functioning using visual evoked potential (VEP) techniques, (2) to examine potential dose-response relationships, and (3) to correlate deficits in vision with performance on the Mullen Scales of Early Learning administered between 14 and 24 months of age. Studied were 21 infants born to women who were exposed occupationally to solvents during pregnancy and 27 non-exposed infants. Mothers and their infants were recruited during pregnancy through the Motherisk Program, an antenatal counseling service in Toronto. In addition, 2 children born to a mother who abused volatile inhalants were examined as reference cases for dose-effect data. A sweep VEP technique was used to assess contrast sensitivity and grating acuity by presenting sinusoidal gratings that "swept" across a range of contrasts and spatial frequencies. A transient VEP technique was used to assess responses to equiluminant chromatic- and luminance-modulated sinusoidal gratings presented in pattern onset-offset format. Exposure level was estimated from questionnaire data obtained during pregnancy. Testers were masked to exposure status. Results showed a significant reduction in contrast sensitivity at low spatial frequencies in solvent-exposed infants compared to control infants (P = .001). Infants with high level exposure had significantly lower acuity than those with low exposure, suggesting evidence of a dose-response relation. Regarding colour vision, 26.3% of infants in the exposed group versus 0% in the control group produced abnormal VEP responses to the red-green stimulus (P &lt; .01), but not to the blue-yellow and achromatic stimulus. Finally, there were no significant correlations between visual deficits and outcomes on neurobehavioural tests. Although knowledge on the mechanisms of solvent-induced visual impairment is largely insufficient, some speculations are made to explain the current findings. Overall, the observed loss in contrast detection and abnormal red-green colour vision suggest a vulnerability of the visual system to prenatal organic solvent exposure.
Notes: Adviser:  Joanne Rovet.

Thesis (Ph.D.)--University of Toronto, 2004.

Electronic version licensed for access by U. of T. users.

Source: Dissertation Abstracts International, Volume: 65-10, Section: B, page: 5452.