The neuroscience of after-images is a lot more complicated. It's certainly possible to cause them by "bleaching" photo-pigments, but this requires extremely br

The neuroscience of after-images is a lot more complicated. It's certainly possible to cause them by "bleaching" photo-pigments, but this requires extremely bright light. Other mechanisms likely produce the after-effects you normally encounter, and even there, eye movements (large and small) should help counter-act them unless the stimulus is very large and bright. I have no doubt that overly contrast-y web pages can cause eye strain, but it's usually not because they're exhausting photoreceptors.