I am not a medical person, just an educated/informed layperson. I’ll take a stab at a couple items until real medical people come along.
I haven’t a clue on this one.
To allow the tissue from the tooth fuse to the lens assembly. In order for that to happen cell growth is required and that means the cells need to be protected and have a good blood supply. Sewing the the stuff under the skin of the chest allows that.
Some other procedures also do this - for example, if someone is in a horrible accident and needs extensive mouth reconstruction part of the jaw bone might be put under the skin of the torso to keep the bone alive until the surgeons can put it back where it belongs. For certain types of head injury part of the skull might be removed to allow the brain to swell (otherwise, the pressure increase might destroy brain tissue) and the piece of skull bone, again, put under the skin of the torso to keep it alive until it can be put back into place. It does sound weird, but if it works it works.
It protects the damaged eye from further damage.
I’m not entirely clear on this part. Yes, your eye has stuff inside although I think it’s more jelly-like than juice-like. The eye can be sewed back up, but replacing the clear eye fluid/jelly and getting the pressure right is difficult. There certainly are ways to get in to the eye for surgery although this is certainly not done lightly.
You have that backward. This will only work if your retina is working correctly, it is intended to correct cornea damage, not retina damage. The woman’s problem was that the surface of her eye, the cornea, was severely scarred. Imagine taking the lens out of a pair of glasses and rubbing it with coarse sandpaper - you might see light through it, but not anything really useful.
You aren’t using the whole tooth, of course. You are creating a disc of very hard substance (the tooth) surrounded by a ring of soft bone that will form attachments. See the third picture over in Stage 1 on your link to see how this works.
The dilemma is how to create a container for the lens out of living tissue. You need something hard enough to create a permanent anchor for the lens and you need it to be able to bond the edges of this implant to the surrounding eye tissue so that it becomes a permanent part of the eye. The tooth is hard enough to hold the lens but too hard for other tissue to attach to. So the strategy is to use a section of tooth right where it is naturally attached to the mandible. The mandible (alveolar) bone there will readily create permanent attachments to soft tissue.
The tooth provides a hard container for the lens. The surrounding bit of mandible contains a living matrix suitable for providing a living attachment to other tissues. Because the hard part (the tooth itself) is attached to the mandibular (jaw) bony matrix, it’s a perfect way to use living tissue.
If you used a prosthetic carrier for the lens, you’d have to have it manufactured in such a way that the central part was rock-hard to carry the lens and there was a surrounding mesh of some sort that could knit to the rest of the eye globe. However whenever possible, implants made from your own tissues are the best, followed by implants made from other humans, followed by implants from animals. Totally artificial implants are usually the last choice.
Implantation under a pocket of skin and the mucosal flap are used to provide a natural layer of connective tissue over the whole thing before it can be used as an implanted graft. Unnecessary tissue covering the lens itself is removed.
Yes there is a clear juice inside the eye. Globes get punctured and sewn back together all the time. Care must be taken not to let the retina detach if the juices run out.
Not sure about the “smart” part. Can I just be a regular medical person explaining this?
I remember a local morning news show (philly, late 70-early 80s) of someone with this condition; apparently, she suffered some disease which fused her eyeball to the inner lining of her eyelid, so doctors built a “periscope” through her eyelid to see.
She had Stevens-Johnson Syndrome. That’s not caused by a particular medication, it’s a bad reaction to a medication (usually - there are other potential causes). It’s not an allergy, but it’s analogous to one in that the person has the reaction to something that in the vast majority of people doesn’t cause that reaction. Blindness is a relatively frequent complication of SJS.