According to an NCBI study, too high of a temperature could cause injury to the eyelid skin, could cause corneal molding, presbyopia, and cataract.
There is evidence that microwave heating masks can get too dangerously high temperatures.
To optimize efficiency, your heating eye mask must meet these criteria:
Maintain steady heat at around 45 C
Direct contact between the heating unit to the outer eyelid areas including inner and outer corners
Duration for at least 20 minutes (it takes 6 minutes for the heat to reach the oil inside the eyelids)
Eyelids skin injury: The eyelid skin is the thinnest layer of skin on the body. It’s unique because it only has two layers instead of three layers like the rest of the skin in our bodies When the temperature is too hot, irreversible damage to the cells can occur.
Studies showed heat and pressure can change the cornea shape, resulting in changing in your glasses prescription.