Only when I wear contacts. I use re-wetting drops while wearing the contacts and when I take them out, I use B&L Opcon-A to cleanse my eyes. I will also sometimes just squeeze some saline in my eyes to make them feel fresh. Inside the plane, the air becomes very dry causing my contacts to also become dry, even though I use hydrated contacts. I wear my contacts when flying, instead of glasses because I can wear sunglasses without having to keep switching back and forth between regular glasses and sunglasses.