Case report: Unilateral optic nerve aplasia and developmental hemi-chiasmal dysplasia with VEP misrouting

• Published in: Documenta ophthalmologica Vol. 142; no. 2; pp. 247 - 255
• Main Authors: Handley, Sian E., Marmoy, Oliver R., Gore, Sri K., Mankad, Kshitij, Thompson, Dorothy A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2021; Springer Nature B.V
• Subjects: Animal models; Aplasia; Case reports; Clinical Case Report; Dysplasia; Electroretinography; Evoked Potentials, Visual; Eye; Humans; Infant; Magnetic resonance imaging; Medicine; Medicine & Public Health; Microphthalmia; Ophthalmology; Optic chiasm; Optic Chiasm - diagnostic imaging; Optic nerve; Optic Nerve - diagnostic imaging; Optic Nerve Diseases - diagnosis; Visual evoked potentials; Chiasm; Misrouting; Visual evoked potential; Optic nerve aplasia; Hemi-chiasm
• ISSN: 0012-4486; 1573-2622
• DOI: 10.1007/s10633-020-09788-7

Purpose To describe the trans-occipital asymmetries of pattern and flash visual evoked potentials (VEPs), in an infant with MRI findings of unilateral optic nerve aplasia and hemi-chiasm dysplasia. Methods A child with suspected left cystic microphthalmia, left microcornea, left unilateral optic nerve aplasia, and hemi-chiasm underwent a multi-channel VEP assessment with pattern reversal, pattern onset, and flash stimulation at the age of 16 weeks. Results There was no VEP evidence of any post-retinal visual pathway activation from left eye with optic nerve aplasia. The VEP trans-occipital distribution from the functional right eye was skewed markedly across the midline, in keeping with significant misrouting of optic nerve fibres at the chiasm. This was supported by the anatomical trajectory of the optic chiasm and tracts seen on MRI. Conclusion This infant has chiasmal misrouting in association with unilateral optic nerve aplasia and unilateral microphthalmos. Chiasmal misrouting has not been found in patients with microphthalmos or anophthalmos, but has been reported after early eye loss in animal models. Our findings contribute to our understanding of the discrepancy between the visual pathway physiology of human unilateral microphthalmia and animal models.