About 20 years ago, on a flight from CDG to LHR, in y, the FA whipped past throught the curtain. The edge of the curtain caught this woman sitting across the aisle in the eye, whipped her glasses off, and left her with a cut across her eye and blood streaming down her face. So I pushed the call button - several times, in view of the urgency - and the FA seemed quite put off by the fact that I'd done so, and was relatively unhelpful about either first aid or finding the passengers glasses. Eventually the purser came and that was different - down to wheelchair, ambulance, the whole lot at LHR. But that's the only time I've used the callbutton, and the FA response made me feel quite guilty about it.