Pupil function after 2+ weeks in a cave

The Thai boys being brought out of the cave are reportedly being fitted with blindfolds and/or sunglasses to limit their exposure to ambient light. How long will they continue to do this? What happens if they don’t do this? Can the kids’ eyes be damaged by bright ambient light (i.e. daylight or “normal” room lighting)?

It’s not the brightness of the light, but the UV radiation. UV rays from sunlight can damage the eyes. Since the pupils will be almost completely dilated, they will be at risk for excessive exposure to UV radiation until their eyes adjust.

There are two additional points: (1) The children may have reduced ability to distinguish color, and certain lenses can help with that. (2) They may have problems with depth perception and balance, and lenses can protect their eyes from falling or bumping into things.

This article might be useful:


The pupillary muscles–particularly two of my three favorite sphincters–actually lose significant ability or speed to contract from disuse?

FTR, traumatic damage to said muscles in my left eye has left me with a pupil permanently at maximum dilation.

:smack: They’re muscles, Einstein.
I got all smarty-pants and side-tracked by the stimulus and refraction curves of rhodopsin, and the phenomenon that children can be blinded permanently if the visual cortex is unstimulated for a long enough time before some cut-off age, despite an otherwise normally functioning optical front end.

It gets weirder than that. They need a variety of visual stimuli early on to assure good vision. Check out this study of cats: one group was exposed only to vertical lines for the first few weeks of their lives, and the other group was exposed only to horizontal lines for the first few weeks of their lives. After this weird upbringing, the first group simply could not see horizontal lines (they wouldn’t jump up onto chairs), and the second group simply could not see vertical lines (they kept banging into chair legs).

Yeah, that makes sense, given the specialization of the cells exactly tuned to filter orientation of light bands.

My interest stems partly from the situation of my eye trauma (referred to above), which happened when I was eight years old, and they tickled and prodded my visual cortex to see if the neurology was still functioning, before any heroic measures to save my eye. Which they did, leaving me blind except for significant light reception, somehow. With a permanently dilated pupil.

I’m the guy who wears an eyepatch at the beach and is never seen in daytime without his cool shades.

Wonder if they got any eye damage from their initial contact with the first diver who found them. He shone a pretty bright light in the cavern and they’d been in pitch darkness for nine days. Of course, he had no choice, but still.

That effect I believe is not damaging, per se, and should be more or less temporarily severe and longer lasting as the gain of the cells adjusts over time (longer for these kids), but still no more than everybody gets when exposed suddenly to light far brighter than what we have dark-adapted to. As said above, the most common danger of (really) bright light is in looking at the sun .and getting zapped by UV.

Although I don’t know if indeed, as occurs with CCD devices, the chemical processes in crazy gain curves can get pushed out of wack, which is not the situation with the kids.

Do your eyes appear to be different colors, a la David Bowie?