hi all….
As rightly answered by aasif dar…that nagative penalty(db) means that we should decrease power so as to reduce the effect of eye closure
i my self thinks now that penalty for eye opening can be both positive and nagative—–gives negative or positive penalty…
I would like to add a link here for more detailed information
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjQgOTZ6LbLAhUDQI4KHRmpA-sQFggbMAA&url=http%3A%2F%2Foptiwave.com%2Fwp-content%2Fuploads%2F2015%2F06%2FAND9075-D.pdf%3Fb82c69&usg=AFQjCNGKHCJi9da1JjS1Ax_KGC9vrTbenw&sig2=34GNVemwRjYBnLqIaw_Y6Q&bvm=bv.116573086,d.c2E
with regards