Dosimetric study on eye's exposure to wide band radio frequency electromagnetic fields: Variability by the ocular axial length

Abstract

This paper evaluates the variability of specific absorption rate (SAR) in the human eye. This variability results from changes in ocular axial length (OAL), which is common in many ophthalmologic and vision abnormalities, including myopia. A generic eye model was reconstructed according to published data. The feasibility of using the generic model in numerical research of electromagnetic fields (EMF) was demonstrated by means of comparative simulations with eye models reconstructed from magnetic resonance (MR) scans. Free-form deformation (FFD) was used to deform the OAL of the generic eye model. Thus, 64 deformed eyes were created and were categorized according to the OAL increase. The finite-difference time-domain (FDTD) method was applied in the simulations. The results revealed that changing the OAL does not increase EMF absorption in the eyes or the eye tissues. No additional induced temperature rise was produced by the changes of OAL. The results also indicated that the non-pathological increment of the OAL, which is inevitable during the childhood, does not increase the SAR in the eyes.

Detailed modeling of palpebral fissure and its influence on SAR and temperature rise in human eye under GHz exposures

“…and ). Our results agree well with reference results, with a difference of 30% found at 5 GHz, which is acceptable in consideration of different models with different resolutions as discussed by Beard et al [] and Li et al []. We also compared ratios of maximum temperature rise in lens and averaged SARs with selected published studies, −0.1 to 0.16°C kg/W in our study agreeing well with 0.1–0.15°C kg/W in Laakso [], and 0.11–0.14°C kg/W in Hirata et al [].…”

“…Boundary conditions for the air and head interfaces are in the form of where is partial derivative in the direction normal to head surface and H is convection coefficient between air and human tissue. −20 W/(m 2 · °C) was used for the heat convection between air and eyeball, in consideration of evaporation of tear film, convective exchange with the air, and radiation exchange with surrounding objects [Hirata et al, ]; 8 W/(m 2 · °C) was used for heat convection between air and skin [Lagendijk, ; Hirata et al, ; Li et al, ].…”

“…Computational studies on EM power absorption and temperature rise in human eye have been investigated [Hirata et al, , ; Buccella et al, ; Laakso, ; Li et al, ]. Several factors, including size of eye [Hirata et al, ], ocular axial length [Li et al, ], thermal parameter [Hirata et al, ], and spatial resolution [Laakso, ], which could influence Specific Absorption Rate (SAR) and temperature calculations, have been proposed and discussed; but no detailed palpebral fissure features have been included in previous investigations.…”

Assessment of Twin Fetal Exposure to Environmental Magnetic and Electromagnetic Fields

“…The field bias/non‐uniformity was corrected by N3 algorithm [Sled et al, 1998], multi‐level thresholding, morphological operations, regional growing, and the graph cut method. The segmentation was conducted semi‐automatically by using in‐house software [Wu et al, 2013; Li et al, 2014]. Two radiologists were recruited to verify the validity of the results.…”

Generation of infant anatomical models for evaluating electromagnetic field exposures

“…Segmentation was performed on two‐dimensional (2D) slices and 3D volumes. The interactive segmentation tool, iSeg (ZMT, Zurich, Switzerland), and in‐house software [Wu et al, ; Li et al, ] based on Insight Segmentation and Registration Toolkit (ITK) [Ibáñez et al, ] and Visualization Toolkit (VTK) [Schroeder et al, ] were used.…”