[COLOR=black][FONT=Trebuchet MS]Are there any optometrist/ophthalmologists in the house?
If someone were to put a lens from a human eye on the table, what would it look like? I don’t want to think about where it came from, we won’t talk about that. I will assume that is cleaned up (no unnecessary gorey parts).
When I pick it up and hold it by the edges, it would feel squishy, right? How squishy? Like Jello, or more like like a soft plastic?
If I held it up to my eye, would it seem to act just like a glass lens? Would it act like a magnifying glass? Could I start a fire with it?
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Here’s the weird thing - removed from the eye, the lens is spheroidal. It’s only in the shape that is in in the eye because it is being pulled at the edges.
I’ve handled human eye lenses (from cadavers – we were taking spectra on them). They’re very jello-like, but with a sort of tougher consistency, so they’re hard to squish apart. They’re very malleable, though.
I wouldn’t call the ones we had spheroidal. They certainly weren’t spherical, but they didn’t have that flattened lenticular sha[pe that give classic lenses their name.
In an anatomy class, I had the opportunity to hold a sheep’s lens, and I assume it’s pretty similar to a human’s. As the other poster says, it was more round than we assume.
It had a texture that I remember being much like stiff gelatin. Jell-o wigglers, where it’s stiff enough to pick up and shake is probably the best example. It also reminded me somewhat of a breast implant.
You couldn’t really see anything through it - there was enough whitish “fog” to prevent you from seeing much. I assume that being dead for a while had clouded the lens. In any event, without muscles to shape it properly, you wouldn’t be able to use it for anything, even fresh and clear.
I recall the guys (and some of the girls) in grade 9 biology throwing the sheep’s lenses (or cow?) around like bouncy-balls. I don’t remember how much they bounced, but everyone kept trying anyways! At the time, it the texture was compared to some of the softer, gooier bouncy-balls you can get.
The lenses I worked with were perfectly clear – otherwise we couldn’t have gotten the light through them to take spectra.
I should point out that they were very fresh. We got them within minutes of being removed from the corpse. This might have helped us get really clear specimens.
The ones I’ve seen were cloudy and yellowish; not fully opaque, but not far from it either. They’d been dead for some time and stored in formaldehyde or some other preservative.
As it happens, I just handled a rainbow trout lens. Verdict for this species: perfectly spherical to my eye, and firm yet jellylike. Kind of like those gel balls that water plants, or maybe like snail eggs but firmer. Also one of the cats, despite being a voracious bastard, wouldn’t eat it.
Cary 14 spectrophotometer. We wanted to see where the lens was absorbing. Actually, a doctor wanted to see this, and was using our equipment. The Cary 14 goes from the UV into the near IR. It’s an old recording spectrophotometer, and is a giant piece of equipment with no digital recording capability. I haven’t seen one since my first job, and I’ll bet they don’t make them anymore.
I don’t know why he wanted the information.
When we were doing the recordings, we placed the lens in a holder, which kept it in a relatively flat shape. I didn’t look through it before mounting, so I couldn’t tell you what it looked like.
I’ve handled plenty of hydrogel contact lenses since, of all prescriptions. Without the support of the eye, they’re floppy and not very good at imaging anything. I suspect the real eye lenses, even though differently shaped and functioning differently, also act this way.