title: Screening and diagnosis of optic pathway gliomas in children with neurofibromatosis type 1 by using sweep visual evoked potentials.
abstract: OBJECTIVE
  Neurofibromatosis type 1 (NF-1) is an autosomal dominant phakomatosis with a prevalence of 1 in 2000 to 1 in 5000. Up to 24% of these patients have optic pathway gliomas (OPGs). In the present study, the use of sweep visual evoked potentials (SVEPs) was investigated as a screening tool for identifying patients with NF-1 who had OPGs by comparing them to those patients with no OPGs and to normally developing children.
  
  
  METHODS
  Contrast sensitivity and grating acuity were measured with the SVEP. Sixteen children with OPGs (OPG group), 14 children with NF-1 without OPGs (nOPG), and 16 aged-matched control subjects were recruited. All participants had best-corrected visual acuity of 6/9 or better. All were tested monocularly.
  
  
  RESULTS
  Comparisons between groups by using the Tukey B test showed a significant reduction of mean log contrast sensitivity in the OPG group (1.55) compared with the nOPG (1.9, P = 0.006) and control (2.10, P < 0.001) group. There was no significant difference between the nOPG and control groups (P = 0.195). Grating acuity was comparable between groups, and no statistically significant differences were found. Log contrast sensitivity was moderately sensitive in identifying patients with OPG and was highly specific in screening out patients with no OPG.
  
  
  CONCLUSIONS
  Children with OPGs have reduced contrast sensitivity when assessed using the SVEP. Children with no OPGs display no differences in visual functioning compared with control subjects. The findings suggest that the SVEP can be a useful and noninvasive screening tool for early detection of visual pathway gliomas in children with NF-1 and normal visual acuity.
authors.affiliation: Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Canada. benjamin_chang@alexhosp.com.sg
authors.forename: Benjamin C M
authors.initials: BC
authors.lastname: Chang
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mirabella
authors.forename: Ronit
authors.initials: R
authors.lastname: Yagev
authors.forename: Michael
authors.initials: M
authors.lastname: Banh
authors.forename: Eedy
authors.initials: E
authors.lastname: Mezer
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Parkin
authors.forename: Carol A
authors.initials: CA
authors.lastname: Westall
authors.forename: J Raymond
authors.initials: JR
authors.lastname: Buncic
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D015350:Contrast Sensitivity / Q000502:physiology*; D003941:Diagnostic Techniques, Ophthalmological; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008297:Male; D009456:Neurofibromatosis 1 / Q000150:complications / Q000175:diagnosis*; D020339:Optic Nerve Glioma / Q000175:diagnosis* / Q000209:etiology; D019574:Optic Nerve Neoplasms / Q000175:diagnosis* / Q000209:etiology; D015351:Vision Screening / Q000379:methods; D014792:Visual Acuity; D014795:Visual Pathways / Q000473:pathology