Configuration of the optic chiasm in humans with albinism as revealed by magnetic resonance imaging.

PURPOSE To determine whether the size and configuration of the optic chiasm in humans with albinism is different from that in normal control subjects. METHODS Seventeen patients and 15 control subjects underwent magnetic resonance imaging of the entire head. Images were reformatted to the chiasm region and analyzed with observer-independent morphometry and measurements by a blinded observer. RESULTS The albino group showed significantly smaller chiasmatic widths, smaller optic nerves and tracts, and wider angles between nerves and tracts. Statistical morphometry showed a different configuration of the optic chiasm. CONCLUSIONS Size and configuration of the optic chiasm in humans with albinism are distinctly different from those in normal control subjects and reflect the atypical crossing of optic fibers.