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Implantable eyelid heater

Treatment for meibomian gland disease
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A small bio-powered heating and sensor unit implanted in or near the supraorbital notch, with a fine silicone-coated heating wire affixed inside the edges of the upper and lower eyelid. The heating element keeps the temperature of the meibomian glands / ducts at between 40-41 degrees Celsius, ensuring proper flow and dispersion into the tear layer at all times.

You could wear existing goofy looking goggles to do this, but an implant would be less hassle - and less goofy looking.

a1, Oct 10 2023

Eyelid Warming Devices https://www.ncbi.nl...rticles/PMC9362510/
The temperature required to soften or liquify pathological meibum is >40c; whereas the melting point for normal meibum is approximately 34c;. [a1, Oct 10 2023]

Biochemistry, tear film https://www.ncbi.nl...ov/books/NBK572136/
[a1, Oct 11 2023]

[link]






       As an alternative to a battery and a sensor set, it could simply be a thin silicone strip embedded with a few micrograms of plutonium 238. Plastic would have to absorb alpha emissions to avoid cataracts though.
a1, Oct 10 2023
  

       It's non trivial to work out how much energy would be required for this. My 1st thoughts were in the ~1W per eye range since we only need ~3°C above the existing temperature provided by blood circulation. But that's incomplete thinking. As soon as you get above 37°C the blood starts to behave like active liquid cooling, then you have to battle increases evaporation of water on the eye surface and any sweat (are there sweat glands around the eye? Would be a silly place to put them). Based on the published glucose fuel cell power density of 43uW/cm2 you'd need ~50,000cm2 to power 2W heaters. That's somewhat impractical.
bs0u0155, Oct 11 2023
  

       Non-trivial, but how would you refine your first guess of 1 watt? Seems too high. I'm only trying to heat up a tiny area in and around the duct work to soften up a likewise tiny amount of stuff.   

       How tiny? The entire tear film is secreted at a rate of between 1 to 2 milligrams per minute (link) and the meibomian secretions are less than half of that. Once they're softened up enough to flow/mix into the lacrimal components, that solves the evaporation problem.
a1, Oct 11 2023
  

       Ah, I thought you were going for the whole eyelid. Lots of variables regarding air temperature and so on. It takes a 10W heater to heat up my microscope objective to around 38C inside a 37C chamber. Now, that objective is a lot more mass but similar area to a pair of eyelids, and I have no idea of the duty cycle of the temperature controller, so I just went with ~10x less. Even if it's 10x less, that's still a lot of fuel cell area.
bs0u0155, Oct 11 2023
  

       I have no idea either and we may not be comparing it to the right things. It's very different than heating my coffee or your microscope. Lipids (not water), confined within tiny ducts, and we just need to soften it enough to squeeze it out when you blink (which may not need to liquify it).   

       How much power do you need to raise 1 milligram of (oil? paraffin?) by 1C in one minute?
a1, Oct 11 2023
  

       //How much power do you need to raise 1 milligram of (oil? paraffin?) by 1C in one minute?//   

       ~2J/g/K. So 2.0x10^-3J. So 0.000003 Watts. That would put you at ~10cm2 of the glucose fuel cell, that's doable since it could be stacked plates in a ~2cm cube. The problem is you're not just heating that 1mg. It's all embedded in epidermis/dermis etc. That's all perfused at the micrometer level by blood-filled capillaries.   

       The way I'd go is a pair of glasses with small heated pads exdending back from the nose pads to contact the right area, even a lithium coin cell should be enough for a few hours.   

       Alternatively you could paint on/embed a tiny coil/resistor and transfer energy using an oscillating electromagnetic field, like a wireless phone charger. Put the charging coils in the glasses too.   

       Another idea might be to paint the whole area to be heated with a fluorophore that emits in the Infra Red... although you'd get the same effect with black.
bs0u0155, Oct 11 2023
  

       Maybe it's my fault for originally suggesting "bio-powered" but I think you're too enamored of glucose metabolism. Let's use plutonium-238. Direct heat output of half a watt per gram initially, with a half life of 87.7 years so it won't diminish significantly during the expected life of the patient.   

       The alpha emissions may even stimulate the glands irrespective of heat output. More research is needed.
a1, Oct 12 2023
  

       No input. Just learning. Fascinating. As you were. (+)   

       Hmm ... there seems to be something in my eye ... [+]
pertinax, Oct 12 2023
  

       //I think you're too enamored of glucose metabolism.//   

       Who do you think I am, Otto Warburg?!*   

       Oxidizing glucose isn't particularly energy dense, but it's quite convenient. the problem is that it's half-oxidized already. Fatty acids by contrast are very reduced. It's a bit like burning alcohol vs diesel. To metabolize fatty acids you have to overcome the fact that they're not water soluble, they're large unwieldy molecules, and you have to use high energy/dangerous biochemistry to break them apart. That's what mitochondria specialize in. They generate a voltage approaching 180mV. Furthermore, there's evidence** that they may be 50C inside. Certainly, they're responsible for the overwhelming majority of body heat in mammals and birds.   

       You can't just do mitochondria on a chip however, they need cells around them for all the life-support biochemistry & molecular biology. We do have tissue specialized in burning fat to make heat: brown fat. Maybe some brown fat could be harvested and carefully deposited around the glands?   

       *A Joke for the metabolism crowd there... **I'm not sure to what level I'm convinced by it.
bs0u0155, Oct 12 2023
  

       That joke will land one day, but we'll have to wait for orbital decay to set in.
pertinax, Oct 12 2023
  

       This morning I though of an entirely practical variant on this idea. was eager to post it on HB as a new idea but found lots of patents. So I'll just hang my not really new idea on to this one.   

       Heated Eyedrops. As long as a dry-eye sufferer is using drops many times during the day, why not heat them up to just a little above a comfortable temperature help unclog the other glands.   

       I tested this on myself this morning - floated some of those little single-use vials in a mug of hot water before use. It did seem to be an improvement but the effect didn't last very long. Maybe a slightly different formulation of drops that are meant to be heated would work better.   

       As I said, I found a lot of patents for similar ideas - but I don't see any products based on this.
a1, Oct 17 2023
  
      
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