Characteristics of ocular temperature elevations after exposure to quasi- and millimeter waves (18-40 GHz)

Masami Kojima,Yukihisa Suzuki,Yoshitsugu Kamimura,Cheng-Yu Tsai,Hiroshi Sasaki,Kazuyuki Sasaki,Akimasa Hirata,Soichi Watanabe,Masao Taki,Kensuke Sasaki,Kanako Wake

doi:10.1007/s10762-014-0142-4

Abstract

In order to investigate changes in ocular temperature in rabbit eyes exposed to different frequencies (18 to 40 GHz) of quasi-millimeter waves, and millimeter waves (MMW). Pigmented rabbits were anesthetized with both general and topical anesthesia, and thermometer probes (0.5 mm in diameter) were inserted into their cornea (stroma), lens (nucleus) and vitreous (center of vitreous). The eyes were exposed unilaterally to 200 mW/cm2 by horn antenna for 3 min at 18, 22 and 26.5 GHz using a K band exposure system or 26.5, 35 and 40 GHz using a Ka band exposure system. Changes in temperature of the cornea, lens and vitreous were measured with a fluoroptic thermometer. Since the ocular temperatures after exposure to 26.5 GHz generated by the K band and Ka band systems were similar, we assumed that experimental data from these 2 exposure systems were comparable. The highest ocular temperature was induced by 40 GHz MMW, followed by 35 GHz. The 26.5 and 22 GHz corneal temperatures were almost the same. The lowest temperature was recorded at 18 GHz. The elevation in ocular temperature in response to exposure to 200 mW/cm2 MMW is dependent on MMW frequency. MMW exposure induced heat is conveyed not only to the cornea but also the crystalline lens.

Highlights

Quasi-millimeter waves and millimeter waves (MMWs) are prevalent in high-speed wireless communication, automobile collision prevention systems and high-resolution radar imaging
The elevation in ocular temperature in response to exposure to 200 mW/cm2 MMW is dependent on MMW frequency
All eyes were exposed to the same incident power density of MMWs, those exposed to 40 GHz had a 1.6-fold higher corneal temperature than those exposed to 18 GHz

Summary

Introduction

Quasi-millimeter waves and millimeter waves (MMWs) are prevalent in high-speed wireless communication, automobile collision prevention systems and high-resolution radar imaging. Many studies have assessed the effects of microwave exposure on the eye, few studies have evaluated the specific effects of MMWs [2,3,4,5,6]. 107 GHz effectively produced immediate stromal damage, which was generally gone by the day, whereas the effects of 35 GHz were persistent and were almost always present the day [2]. Taken together, these findings suggest that different frequencies have different ocular effects

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Results

Conclusion