Abstract
Purpose: :
No differences between nystagmus associated with albinism and idiopathic infantile nystagmus (IIN) have been described. Recently mutations in a novel gene called FRMD7 have been found which allow definitive identification of a homogenous group of idiopathic nystagmus patients. We have compared clinical and eye movement characteristics between albinism and IIN with and without mutations in the FMRD7 gene
Methods: :
Visual acuities and eye movements (infrared pupil tracker) were recorded from 50 albino subjects, 83 subjects with the FRMD7 mutation and 45 subjects without the FRMD7 mutation
Results: :
Mean visual was significantly worse in albinos compared to IIN patients (p<<0.0001). Although there was no significant differences between the groups (p>0.05) for nystagmus amplitude, the frequency of nystagmus was significantly slower in albinism (p<<0.0001). In addition, nystagmus associated with albinism was significantly more likely to be jerk nystagmus rather than pendular nystagmus compared to FRMD7 group (p<<0.0001). The most common waveform associated with albinism was pure jerk nystagmus, whereas non-FRMD7 was more likely to be associated with jerk with extended foveation
Conclusions: :
Contrary to available literature, nystagmus associated with albinism shows distinct differences to IIN both with and without FRMD7 mutations. This suggests the possibility of different underlying mechanisms to albinism and IIN in generating eye oscillations although these are yet to be elucidated
Keywords: nystagmus • genetics • eye movements