Compression of the prechiasmatic optic nerve produces a junctional scotoma.

PURPOSE To demonstrate the clinical-radiologic correlation between a junctional scotoma and a focal lesion compressing the prechiasmatic segment of the distal optic nerve. METHODS Case report involving a man with a pituitary adenoma. Clinical correlation was determined by reviewing visual field evaluations and magnetic resonance images. RESULTS The tumor compressed the prechiasmatic segment of the distal optic nerve but not the optic chiasm, producing a junctional scotoma documented by Goldmann and automated perimetry. The visual field defect resolved after neurosurgical decompression of the anterior visual pathway. CONCLUSIONS A junctional scotoma can be caused by focal as well as large and diffuse lesions injuring the anterior visual pathway, specifically at the junction of the optic nerve and chiasm. This finding supports the existence of Wilbrand fibers.