Effect Of Prolonged Monocular Occlusion On Latent Nystagms
Neuro-Ophthalmology , Volume 12 - Issue 3 p. 185- 192
The authors recorded nystagmus during seeing with one eye in eight patients with latent nystagmus (LN) before and after two or three days of prolonged occlusion of the better eye (POBE). Before POBE, the slow-phase speed of the nystagmus (SPS) was usually higher when the better eye was covered. After POBE, the SPS during cover of the better eye had decreased and the SPS during cover of the poorer eye had increased (please note the time difference between ‘prolonged occlusion’ and ‘cover'). However, the sum of the two speeds (absolute values, for they were opposite in direction) remained the same in all cases. This indicates that the principal component of the LN, the difference between LN with right-and LN with left-eye cover, remained the same, but a drift towards the poorer eye had been added that decreased the SPS during cover of the better eye and increased the SPS during cover of the poorer eye. In three patients who had oscillopsia during POBE, the oscillopsia gradually decreased over days during POBE, indicating that the drift changes slowly, over a period of days. As regards occlusion therapy in children with amblyopia and latent nystagmus, based on these findings, it seems advisable to occlude the better eye during days per week, rather than during hours per day: Then there is more time for the nystagmus to decrease, so that amblyopia therapy can be more effective.