For Speedy, in case you don’t find my Chat reply.
https://www.scientificamerican.com/article/eye-opener-why-do-pupils-dialate/
The drops for pupil dilation knock out the nerves to the muscles which constrict the pupil and let the dilating muscles over-ride. They are anti-cholinergics, they mess with the acetylcholine neurotransmitter.
Thanks buffy.
I had no idea that there were two sets of eye muscles working simultaneously. It’s interesting that the eye drops affect only one set of muscles to make pupil dilation occur.
_The iris is made of two types of muscle: a ring of sphincter muscles that encircle and constrict the pupil down to a couple of millimeters across to prevent too much light from entering; and a set of dilator muscles laid out like bicycle spokes that can expand the pupil up to eight millimeters—approximately the diameter of a chickpea—in low light.
Stimulation of the autonomic nervous system’s sympathetic branch, known for triggering “fight or flight” responses when the body is under stress, induces pupil dilation. Whereas stimulation of the parasympathetic system, known for “rest and digest” functions, causes constriction. Inhibition of the latter system can therefore also cause dilation. The size of the pupils at any given time reflects the balance of these forces acting simultaneously._
buffy said:
For Speedy, in case you don’t find my Chat reply.https://www.scientificamerican.com/article/eye-opener-why-do-pupils-dialate/
The drops for pupil dilation knock out the nerves to the muscles which constrict the pupil and let the dilating muscles over-ride. They are anti-cholinergics, they mess with the acetylcholine neurotransmitter.
One thing I’ve been wondering lately. Why don’t pupils dilate during sleep with eyelids closed? I find that when I wake up I’m not dazzled by the brightness of the light.
mollwollfumble said:
buffy said:
For Speedy, in case you don’t find my Chat reply.https://www.scientificamerican.com/article/eye-opener-why-do-pupils-dialate/
The drops for pupil dilation knock out the nerves to the muscles which constrict the pupil and let the dilating muscles over-ride. They are anti-cholinergics, they mess with the acetylcholine neurotransmitter.
One thing I’ve been wondering lately. Why don’t pupils dilate during sleep with eyelids closed? I find that when I wake up I’m not dazzled by the brightness of the light.
Then there is something wrong with your eyes…
Speedy said:
Thanks buffy.I had no idea that there were two sets of eye muscles working simultaneously. It’s interesting that the eye drops affect only one set of muscles to make pupil dilation occur.
_The iris is made of two types of muscle: a ring of sphincter muscles that encircle and constrict the pupil down to a couple of millimeters across to prevent too much light from entering; and a set of dilator muscles laid out like bicycle spokes that can expand the pupil up to eight millimeters—approximately the diameter of a chickpea—in low light.
Stimulation of the autonomic nervous system’s sympathetic branch, known for triggering “fight or flight” responses when the body is under stress, induces pupil dilation. Whereas stimulation of the parasympathetic system, known for “rest and digest” functions, causes constriction. Inhibition of the latter system can therefore also cause dilation. The size of the pupils at any given time reflects the balance of these forces acting simultaneously._
There are other drops which affect the other muscles, which constrict the pupil. When I began in practice, a miotic (pupil constrictor) drug was the drug available for glaucoma treatment. It wasn’t much fun. It made your pupils really pinpoint and gave you browache. It is called Pilocarpine. We were told “patients hate pilo”. But at the time, it’s what there was, and the alternative was going blind from the glaucoma. There are a lot more drugs which are kinder to the patient now, but Pilocarpine is still sometimes used.
mollwollfumble said:
buffy said:
For Speedy, in case you don’t find my Chat reply.https://www.scientificamerican.com/article/eye-opener-why-do-pupils-dialate/
The drops for pupil dilation knock out the nerves to the muscles which constrict the pupil and let the dilating muscles over-ride. They are anti-cholinergics, they mess with the acetylcholine neurotransmitter.
One thing I’ve been wondering lately. Why don’t pupils dilate during sleep with eyelids closed? I find that when I wake up I’m not dazzled by the brightness of the light.
The light reflex is fast.
buffy said:
Speedy said:
Thanks buffy.I had no idea that there were two sets of eye muscles working simultaneously. It’s interesting that the eye drops affect only one set of muscles to make pupil dilation occur.
_The iris is made of two types of muscle: a ring of sphincter muscles that encircle and constrict the pupil down to a couple of millimeters across to prevent too much light from entering; and a set of dilator muscles laid out like bicycle spokes that can expand the pupil up to eight millimeters—approximately the diameter of a chickpea—in low light.
Stimulation of the autonomic nervous system’s sympathetic branch, known for triggering “fight or flight” responses when the body is under stress, induces pupil dilation. Whereas stimulation of the parasympathetic system, known for “rest and digest” functions, causes constriction. Inhibition of the latter system can therefore also cause dilation. The size of the pupils at any given time reflects the balance of these forces acting simultaneously._
There are other drops which affect the other muscles, which constrict the pupil. When I began in practice, a miotic (pupil constrictor) drug was the drug available for glaucoma treatment. It wasn’t much fun. It made your pupils really pinpoint and gave you browache. It is called Pilocarpine. We were told “patients hate pilo”. But at the time, it’s what there was, and the alternative was going blind from the glaucoma. There are a lot more drugs which are kinder to the patient now, but Pilocarpine is still sometimes used.
Only ever see the carpine being used short term these days.
poikilotherm said:
buffy said:
Speedy said:
Thanks buffy.I had no idea that there were two sets of eye muscles working simultaneously. It’s interesting that the eye drops affect only one set of muscles to make pupil dilation occur.
_The iris is made of two types of muscle: a ring of sphincter muscles that encircle and constrict the pupil down to a couple of millimeters across to prevent too much light from entering; and a set of dilator muscles laid out like bicycle spokes that can expand the pupil up to eight millimeters—approximately the diameter of a chickpea—in low light.
Stimulation of the autonomic nervous system’s sympathetic branch, known for triggering “fight or flight” responses when the body is under stress, induces pupil dilation. Whereas stimulation of the parasympathetic system, known for “rest and digest” functions, causes constriction. Inhibition of the latter system can therefore also cause dilation. The size of the pupils at any given time reflects the balance of these forces acting simultaneously._
There are other drops which affect the other muscles, which constrict the pupil. When I began in practice, a miotic (pupil constrictor) drug was the drug available for glaucoma treatment. It wasn’t much fun. It made your pupils really pinpoint and gave you browache. It is called Pilocarpine. We were told “patients hate pilo”. But at the time, it’s what there was, and the alternative was going blind from the glaucoma. There are a lot more drugs which are kinder to the patient now, but Pilocarpine is still sometimes used.
Only ever see the carpine being used short term these days.
It’s pretty horrible for the user.