[theophrastus]

Thank you for that link (it really helped)

There is anecdotal evidence that the since the proteins in the human lens become opaque (absorptive) in the near infrared (search: crystallin transmission spectrum); that patients who have had their lenses removed for cataract surgery see beyond both traditional limit ends (as the polymer lens replacement has a different transmission spectrum) ... so [semi-serious-only] perhaps it would be more efficacious to have one lens removed? (no lens over a snake's thermal pits etc)

[mikeash]

Just providing one of those anecdotes: my father's cataract surgery extended his vision into the near ultraviolet. We discovered this when we walked past a window of a room containing a black light, and he remarked at the bright purple glow coming from within, whereas I could barely see it. Fascinating stuff.