Neuroscience 2003 Abstract
| Presentation Number: | 263.11 |
|---|---|
| Abstract Title: | Anatomical abnormalities in the optic chiasm, nerves and tracts of human subjects with albinism as assessed by MRI. |
| Authors: |
von dem Hagen, E. A. H.*1
; Houston, G. C.1
; Hoffmann, M. B.1
; Morland, A. B.1
1Psychology, Royal Holloway Univ. London, Egham, Surrey, United Kingdom |
| Primary Theme and Topics |
Sensory Systems - Vision -- Subcortical visual pathways |
| Secondary Theme and Topics | Development<br />- Development of Sensory and Limbic Systems<br />-- Visual system |
| Session: |
263. Retina: Organization Poster |
| Presentation Time: | Sunday, November 9, 2003 3:00 PM-4:00 PM |
| Location: | Morial Convention Center - Hall F-I, Board # E1 |
| Keywords: | development, albino, retina, LGN |
Albinism causes foveal hypoplasia and an abnormally large number of fibres from temporal retina to cross the chiasmatic midline. Previous MRI work (Schmitz et al 2003 IOVS, 44 16-21) has indicated that the dimensions of the optic chiasm are abnormal in human subjects with albinism. The same subjects also showed a narrowing of the optic nerves and tracts and an increased angle between the nerves and tracts. Thus, abnormal crossing of visual fibres and reduced foveal cell numbers appear to have an effect on the gross anatomy of the optic chiasm. We have made a series of anatomical measurements of the optic chiasm, optic nerves and tracts based on T1-weighted (1x0.98x0.98mm) structural MRI scans of 20 control subjects (mean age, 34±11) and 19 subjects with albinism (mean age, 33±11). Similar to the previous study, we found that the dimensions of the chiasm were different for the two groups (albino width=9.3±1.0mm, control width=11.5±1.9mm , albino height=3.7±0.9mm, control height=3.4±0.7mm), but this only reached significance for the width of the chiasm (p=0.0004). The optic nerves were also narrowed in subjects with albinism (albino=3.5±0.4mm, control=4.3±0.7mm, p<0.0001), but narrowing did not reach statistical significance in the tracts (albino=3.1±0.5mm, control=3.3±0.5mm, p=0.11). The angles between the optic nerves and tracts showed no significant difference between groups (albino=79°±9° and 90°±7° for nerves and tracts, control=76°±9° and 85°±9°, p=0.38 and 0.07). It appears, therefore, that the abnormalities we observe in subjects with albinism are most likely associated with the reduced number of retinal cells characteristic of albinism. However, the reduced cell numbers in the fovea and abnormal fibre crossing at the chiasm do not appear to have an impact on the angle between the optic nerves and tracts in albinism as previously reported.
Supported by The Wellcome Trust, London, UK
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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