Temperature elevation in the eye of anatomically based human head models for plane-wave exposures

Area of Science:

• Biophysics
• Computational Electromagnetics
• Ophthalmology

Background:

• Understanding eye temperature elevation from electromagnetic (EM) wave exposure is crucial for safety guidelines.
• Previous studies have shown varying results, necessitating a re-evaluation with anatomically accurate models.

Purpose of the Study:

• To investigate temperature elevation in human eye models exposed to plane-wave EM fields.
• To analyze the frequency-dependent heating factor for the eye lens.

Main Methods:

• Utilized the finite-difference time-domain (FDTD) method for EM absorption and thermal analysis.
• Employed anatomically based human head models with average eye dimensions and weight.

Main Results:

• The ratio of maximum lens temperature to eye-average specific absorption rate (SAR), termed 'heating factor for the lens', remained uniform (0.112-0.147 °C kg W⁻¹) below 3 GHz.
• Above 3 GHz, the heating factor increased with frequency, linked to decreased EM wave penetration depth.
• Reconciled differences with prior studies, finding good agreement after compensation.

Conclusions:

• Eye lens heating is relatively consistent at lower frequencies but becomes more pronounced at higher frequencies.
• The study provides a refined understanding of EM-induced eye heating, crucial for setting exposure limits.