Nonuniform Exposure to the Cornea from Millimeter Waves.

Area of Science:

• Ophthalmology
• Biophysics
• Electromagnetics

Background:

• Previous studies observed significant corneal temperature variations from millimeter wave (mm-wave) exposure due to wave interference.
• Corneal damage thresholds (ED50) were estimated in prior research on rhesus corneas exposed to 94 GHz mm-waves.

Purpose of the Study:

• To investigate the nonuniform absorption and temperature increases in the human cornea from incident 100 GHz millimeter waves.
• To estimate thresholds for thermal lesions in the cornea resulting from high-intensity pulsed mm-wave exposure.

Main Methods:

• High-resolution simulations of mm-wave absorption and temperature increase in the human cornea at 100 GHz.
• Modeling based on plane wave energy and incorporating wave interference effects.
• Estimating thermal lesion thresholds using infrared energy damage data and a thermal damage model.

Main Results:

• Simulations revealed peak corneal temperature increases 1.7-2.8 times the median increase for short exposures (up to 10 s), dependent on incident energy polarization.
• A simple one-dimensional model accurately estimated the median temperature increase.
• Two distinct estimates for thermal lesion thresholds were provided in terms of minimum incident 100 GHz pulse fluence.

Conclusions:

• Interference effects lead to highly localized energy absorption variations in the cornea and surrounding tissues.
• Understanding these localized variations is crucial for hazard analysis of intense pulsed mm-wave exposures.
• Considered mm-wave pulses exceed current exposure limits and may be relevant to nonlethal weapons systems.