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

Handley, Siân E.; Marmoy, Oliver R.; Gore, Sri; Mankad, Kshitij; Thompson, Dorothy

doi:10.1007/s10633-020-09788-7

Cited by 2 publications

(1 citation statement)

References 35 publications

(51 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To date, all achiasmia cases previously described were considered sporadic. 7 , 30 , 33-35 The literature about ONH is more controversial with multiple aetiologies being reported, including mutations in PAX6 , HESX1 and SOX2 genes or various environmental factors such as maternal diabetes and foetal alcohol syndrome. 47 Further genetic and foetal development studies are needed to further understand these conditions that could be part of the same spectrum.…”

Section: Discussionmentioning

confidence: 99%

Clinical features and imaging characteristics in achiasmia

Pilat,

McLean,

Vanina

et al. 2023

Brain Communications

View full text Add to dashboard Cite

Achiasmia is a rare visual pathway maldevelopment with reduced decussation of the axons in the optic chiasm. Our aim was to investigate clinical characteristics, macular, optic nerve and brain morphology in achiasmia. A prospective, cross-sectional, observational study of 12 participants with achiasmia [8 males and 4 females; 29.6 ± 18.4 years (mean ± standard deviation)] and 24 gender-, age-, ethnicity- and refraction-matched healthy controls was done. Full ophthalmology assessment, eye movement recording, a high-resolution spectral-domain optical coherence tomography of the macular and optic disc, five-channel visual-evoked responses, eye movement recordings and MRI scans of the brain and orbits were acquired. Achiasmia was confirmed in all 12 clinical participants by visual-evoked responses. Visual acuity in this group was 0.63 ± 0.19 and 0.53 ± 0.19 for the right and left eyes, respectively; most participants had mild refractive errors. All participants with achiasmia had see-saw nystagmus and no measurable stereo vision. Strabismus and abnormal head position were noted in 58% of participants. Optical coherence tomography showed optic nerve hypoplasia with associated foveal hypoplasia in four participants. In the remaining achiasmia participants, macular changes with significantly thinner paracentral inner segment (P = 0.002), wider pit (P = 0.04) and visual flattening of the ellipsoid line were found. MRI demonstrated chiasmatic aplasia in 3/12 (25%), chiasmatic hypoplasia in 7/12 (58%) and a subjectively normal chiasm in 2/12 (17%). Septo-optic dysplasia and severe bilateral optic nerve hypoplasia were found in three patients with chiasmic aplasia/hypoplasia on MRI. In this largest series of achiasmia patients to date, we found for the first time that neuronal abnormalities occur already at the retinal level. Foveal changes, optic nerve hypoplasia and the midline brain anomaly suggest that these abnormalities could be part of the same spectrum, with different manifestations of events during foetal development occurring with varying severity.

show abstract

Section: Discussionmentioning

confidence: 99%

Clinical features and imaging characteristics in achiasmia

Pilat,

McLean,

Vanina

et al. 2023

Brain Communications

View full text Add to dashboard Cite

show abstract

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

et al. 2020

Self Cite

View full text Add to dashboard Cite

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 postretinal 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.

show abstract

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

Cited by 2 publications

References 35 publications

Clinical features and imaging characteristics in achiasmia

Clinical features and imaging characteristics in achiasmia

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

Contact Info

Product

Resources

About