Session: Poster session A

The effect of prolonged monocular occlusion on the nystagmus waveform in strabismic amblyopia with Manifest Latent Nystagmus

PURPOSE:

Managing strabismic amblyopia in children with manifest latent nystagmus (MLN) can be difficult, as intensity of nystagmus increases with occlusion, which equates to a reduction in visual acuity (VA).  As a result, many do not offer active intervention. In our study, we assessed VA and eye movement recordings in children with MLN and strabismic amblyopia to determine the effect of monocular occlusion.



METHODS:

A prospective case series of 10 children (5-8 years) with strabismic amblyopia and MLN was conducted. Detailed history, full ophthalmic examination and orthoptic assessment were performed. The non-amblyopic eye was occluded continuously for 6 hours.  VA and eye movement recordings were assessed at baseline and at 2-hour intervals, using an EyeLink-1000 video-based eye tracker.



RESULTS:

100% of the children were compliant with continuous occlusion.  80% had previous amblyopia treatment (conventional occlusion therapy/atropine penalization). After 6 hours of continuous occlusion all demonstrated improvement in VA in the amblyopic eye (mean of 0.33 logMAR from baseline), and reduction in velocity and amplitude of nystagmus waveform (mean 9 degrees/second and 8 degrees respectively).

 

CONCLUSIONS:

Evidence reported in literature on the management of MLN is limited.  The fear of worsening the nystagmus (and VA) with occlusion may deprive these children from receiving appropriate treatment to optimise vision during the amblyogenic period. Our study shows that continuous occlusion of the non-amblyopic eye is beneficial in improving the VA and nystagmus parameters in the amblyopic eye and should be considered as a treatment option.