Achiasmia in a case of midline craniofacial cleft with seesaw nystagmus.

Achiasmia and unilateral optic nerve hypoplasia in an otherwise healthy infant

“…An extensive review of the literature found only one other case of isolated bilateral aplasia of the optic nerves, chiasm and tracts in an otherwise healthy 2-month-old female infant (Scott et al 1997). The isolated findings in our patient underscored the important distinction between classic congenital achiasmia and many other cases of structural and functional achiasmia with associated developmental anomalies like midline craniofacial clefting (Leitch et al 1996), or achiasmia secondarily induced from tumour growth (Dutton 1994) or trauma. In a study designed to demonstrate that chiasmal hypoplasia or total achiasmia need not be an isolated developmental anomaly, Thompson et al (1999) gathered and clinically analysed data from five young patients who each demonstrated a different degree of afferent fibre paucity at the optic chiasm by VEP and MRI testing.…”

“…A similar case of isolated congenital achiasmia was documented in another 15-year-old girl, but in her case there was only a predominantly horizontal nystagmus, without evidence of a see-saw component (Jansonius et al 2001). See-saw nystagmus was observed in a separate case report involving a 4-month-old female infant with achiasmia, but this patient also had associated brain abnormalities including midline craniofacial cleft lip and nasoethmoidal encephalocele (Leitch et al 1996). Interestingly in this case, there was no horizontal nystagmus or strabismus.…”

“…The result of the VEP of the left eye in our patient was consistent with an achiasmic or non-decussating retinal-fugal fibre syndrome, with no crossing of fibres to the opposite hemispheres and only ipsilateral occipital responses to ocular stimulation (Apkarian et al 1993(Apkarian et al , 1995Dutton 1994;Thompson et al 1999). With appropriate age-dependent misrouting protocols the electrophysiological testing is considered remarkably sensitive and specific for detecting albinism and achiasmia (Leitch et al 1996). However, the lack of a normal response with stimulation of the right eye is unusual for achiasmia alone.…”

Optic nerve axons: life and death before birth

“…237 Achiasmic patients can have good, 238,239 and sometimes remarkably normal vision despite MRI-and fMRI-proven functional achiasmia. 240 In the case studied by Victor et al, 240 vernier acuity was normal, and there was no evidence for the confounding of visual information between the overlapping ipsi-lateral and contralateral representations.…”

“…230,233,238,239,242 Abnormalities of a number of genes 243 and guidance proteins 77 may be associated with chiasmal maldevelopment.…”