I ordered my first pair two years ago and I'm just now ordering a replacement set - my current ones aren't shot by any means, but the lens has accumulated minor scratches over time and the nosepiece is wearing out. I wear these in a Semiconductor fab for nearly 12hrsday and I barely notice they're there.
The blue tint is very nice as well - I ordered these because the lens tint color is close to the Irlen page overlays I have, and the blue tint also helps to keep me awake under the orange lights in the fab, especially working nights. I absolutely love these glasses!