Investigation of ocular damage threshold by millimeter wave exposure … · ·...

Investigation of ocular damage threshold by millimeter wave threshold by millimeter wave

exposure (40, 75, 95 GHz)

M. Kojima 1,2), Y. Suzuki 3), K. Sasaki 4), T. Tasaki 1)

T. Okuno 3), K. Wake 4), S. Watanabe4), M. Taki 3)

H S ki 1 2)H. Sasaki 1,2)

1 Division of Vision Research for Environmental Health Medical1. Division of Vision Research for Environmental Health, MedicalResearch Institute, Kanazawa Medical University

2. Department of Ophthalmology, Kanazawa Medical University3 Department of Electrical Engineering Tokyo Metropolitan University3. Department of Electrical Engineering, Tokyo Metropolitan University4. National Institute of Information and Communications Technology

1

Methods

Rabbits were exposed to MMWs at frequencies of 40,p q ,75, and 95 GHz for 6 minutes.

One day after exposure morphological changes in theOne day after exposure, morphological changes in thecornea were assessed by slit-lamp microscopy(including fluorescence staining) and optical(including fluorescence staining) and opticalcoherence tomography.

D d t f l i j ( lDose-response data of corneal injury (cornealepithelium damage, corneal opaque, and cornealedema) at each frequency were obtained byedema) at each frequency were obtained byexperiments in the range of power density.

２

MMW exposurepIncident power density: Power density averaged over a13 mm diameter circle corresponding to the area of the

Beam profile

13-mm-diameter circle corresponding to the area of theocular surface exposed to the ambient air.

40 GH

Beam profile

95 GHFWHM: full width at half maximum

]

13 mm in diameter40 GHz

]

13 mm in diameter95 GHz

field

[V/m

]

FWHM 9.6 mm fie

ld [V

/m]

Ele

ctric

f 9.6 mm

FWHM 3.7 mmE

lect

ric f

Distance [mm] Distance [mm]３

75 GHz, 200 mW/cm2 30 min. exposureExposed Non-exposed

BeforeExpo.

p p

p

10 min.after

Corneal average surface

Expo.Miosis+

mm

atio

n)

(sur

face

) temperature(during exposure)

49.2±1.5℃

1 dayafterExpo.

Non-exposed contralateral eyes showed no ocularag

e (in

flam

dam

age

(2 daysafterExpo.

no ocular damage.

omal

dam

a

thel

ial c

ell

p

3 days

Iritis +

orne

al s

tro

orne

al e

pit

yafterExpo.Iritis +

Co

Co

4

Corneal change after 75 GHz, 200 mW/cm2 30 min. exposureExposed eye Non-exposed eye

BeforeExpo.

Numbersindicate corneal thicknessp

1 day

thickness(mm). 0.39 0.41 0.360.39 0.41 0.360.37 0.37 0.390.37 0.37 0.39

1 dayafterExpo.

0.39 0.40 0.360.39 0.40 0.360.45 0.57 0.920.45 0.57 0.92 wel

ling)

o sw

ellin

g)

2 daysafterExpo da

mag

e (s

w

dam

age

(no

Expo.

0.40 0.39 0.380.40 0.39 0.380.95 1.27 1.340.95 1.27 1.34ea

l str

omal

eal s

trom

al

3 daysafterExpo.

0 39 0 39 0 360 39 0 39 0 361 06 1 33 1 401 06 1 33 1 40

Cor

ne

No

corn

e0.39 0.39 0.360.39 0.39 0.361.06 1.33 1.401.06 1.33 1.40

5

40 GHzCorneal

Surface Temp. (ºC)

Corneal EpitheliumDamage

Corneal Opaque Corneal Edema

After 1 day exposure

600 mW/cm2_6 min 49.7 Damage＋(1/1)

Damage＋(1/1)

Damage＋(1/1)

500 mW/cm2 6 min 45 0±2 4 Damage＋ Damage＋ Damage＋500 mW/cm2_6 min 45.0±2.4 (2/2) (2/2) (2/2)

400 mW/cm2_6 min 43.7±3.7 Damage＋（6/8）

Damage＋（5/8）

Damage＋（5/8）

300 mW/cm2_6 min 41.7±1.7 Damage＋（6/8）

Damage＋（5/8）

Damage＋（5/8）

200 mW/cm2_6 min 41.4±1.1 Damage＋（3/6）

Damage－（0/6）

Damage－（0/6）

100 mW/cm2 6 min 37 2±2 9 Damage＋ Damage－ Damage－100 mW/cm _6 min 37.2±2.9（2/8）（0/8）（0/8）

50 mW/cm2_6 min 33.6±1.8 Damage＋（1/7）

Damage－(0/7）

Damage－（0/7）

610 mW/cm2_6 min 32.9±1.3 Damage－

（0/7）Damage－

(0/7）Damage－

(0/7）

75 GH Corneal Surface Corneal Epithelium Corneal Opaque Corneal Edema75 GHzAfter 1 day exposure

Corneal Surface Temp. (ºC)



exposure

300 mW/cm2_6 min 50.7±1.9 Damage＋（3/3）

Damage＋（3/3）

Damage＋（3/3）（3/3）（3/3）（3/3）

200 mW/cm2_6 min 46.2±2.0 Damage＋（5/5）

Damage＋（3/5）

Damage＋（3/5）

150 mW/cm2_6 min 43.5±1.8 Damage＋（3/5）

Damage＋（1/5）

Damage＋（3/5）

Damage＋ Damage－ Damage－100 mW/cm2_6 min 40.5±0.6 Damage＋（1/5）

Damage（0/5）

Damage（0/5）

50 mW/cm2_6 min 37.7±1.9 Damage－（0/3）

Damage－（0/3）

Damage－（0/3）（0/3）（0/3）（0/3）

7

95 GHzCorneal

Surface Temp. (ºC)



95 GHzAfter 1 day exposure

( )

300 mW/cm2_6 min 46.5±1.3 Damage＋（2/3）

Damage＋（2/3）

Damage＋（2/3）

200 W/ 2 6 i 43 5±1 9 Damage＋ Damage＋ Damage＋200 mW/cm2_6 min 43.5±1.9 Damage＋（13/14）

Damage＋（6/14）

Damage＋（6/14）

100 mW/cm2_6 min 36.4±2.9 Damage＋（1/9）

Damage＋（1/9）

Damage＋（1/9）

50 mW/cm2_6 min 34.1±2.3 Damage－（0/4）

Damage－（0/4）

Damage－（0/4）

10 mW/cm2 6 min 32 5±1 5 Damage－ Damage－ Damage－10 mW/cm2_6 min 32.5±1.5 g（0/4）

g（0/4）

g（0/4）

8

Maximum likelihood estimation ith li d li d lwith generalized linear model

• The values of MMW power density which indicate thethreshold of eye damage were defined as damage dose (DD).

• Markers plotted in each graph denote dependence of the ratio• Markers plotted in each graph denote dependence of the ratioof eye damage to the number of exposed eyes to the powerdensity (dose) obtained from actual MMW exposureexperiments.experiments.– The number of rabbit eyes at each power density corresponds to

the marker size. (If the marker size is large, the number of eyesexposed to MMW is large )exposed to MMW is large.)

– Maximum likelihood estimation (MLE) was performed with aprobit model for the experimental data.

– “R” language is used for the MLE.– Black line：result of MLE for GLE

Bl li l li it 95% fid i t l– Blue line：lower limit on a 95% confidence interval– Red line：upper limit on a 95% confidence interval

９

Coefficients obtained by maximum likelihood estimation (MLE)likelihood estimation (MLE)

α Std error of α β Std error of βCorneal epithelium damage

α Std. error of α β Std. error of β40GHz -5.3006 1.5541 1.0274 0.293575GHz -18.724 7.631 3.848 1.54995GHz -12.4396 3.9276 2.5037 0.7755

Corneal opacityα Std. error of α β Std. error of β

40GHz -18.185 6.506 3.158 1.12575GHz 23 697 10 958 4 540 2 11175GHz -23.697 10.958 4.540 2.11195GHz -8.5353 3.6099 1.5773 0.6965

Corneal edemaCorneal edemaα Std. error of α β Std. error of β

40GHz -18.185 6.506 3.158 1.12575GHz -16.629 6.740 3.264 1.32395GHz -8.5353 3.6099 1.5773 0.6965 １０

E d ti 6 iExposure duration = 6 min

１１

Fitting result for 40 GHz(C l ith li d )(Corneal epithelium damage)

１２


１３


１４

Estimation of damage dose (DD) for corneal epithelium

Frequency [GHz] DD [mW/cm2] DD [mW/cm2] DD [mW/cm2]Frequency [GHz] DD10 [mW/cm2] DD50 [mW/cm2] DD90 [mW/cm2]

40 GHz50.0

+ 67.6174

+ 92.0605

+ 712

28 7 60 2 327- 28.7 - 60.2 - 327

75 GHz93.1

+ 41.3130

+ 30.3181

+ 63.8

28 6 24 6 47 2- 28.6 - 24.6 - 47.2

95 GHz86.2

+ 45.9144

+ 37.8240

+ 99.3

29 9 29 9 70 2- 29.9 - 29.9 - 70.2

DD 10% (DD ) DD 50% (DD ) and DD 90% (DD ) wereDD 10% (DD10), DD 50% (DD50), and DD 90% (DD90) wereestimated from each result of MLE for 40, 75, and 95 GHzexposure.p“+” and “-” denotes upper and lower limit of 95% confidenceinterval, respectively. １５

Dependence of damage doseon frequencyon frequency

W/c

m2 ]

ensi

ty [m

Wdo

se: D

D)

pow

er d

eD

amag

e d

Inci

dent

p (D

DD50DDI DD90DD10

１６

E d ti 30 iExposure duration = 30 min

１７

75 GHzAfter 1 day

Corneal Surface Temp. (ºC)



After 1 day exposure

300 mW/cm2_6 min 50.7±1.9 Damage＋（3/3） Damage＋（3/3） Damage＋（3/3）


150 W/ 2 6 i 43 5±1 8 D ＋（3/5） D ＋（1/5） D ＋（3/5）150 mW/cm2_6 min 43.5±1.8 Damage＋（3/5） Damage＋（1/5） Damage＋（3/5）

100 mW/cm2_6 min 40.4±0.6 Damage＋（1/3） Damage－（0/3） Damage－（0/3）

50 mW/cm2_6 min 37.7±1.9 Damage－（0/3） Damage－（0/3） Damage－（0/3）

300 mW/cm2 30 min 53 6±2 8 Damage＋（3/3） Damage＋（3/3） Damage＋（3/3）300 mW/cm _30 min 53.6±2.8 Damage＋（3/3） Damage＋（3/3） Damage＋（3/3）



50 mW/cm2_30 min 37.1±0.8 Damage＋（4/5） Damage＋（1/5） Damage＋（1/5）g g g

10 mW/cm2_30 min 33.8±0.8 Damage－（0/3） Damage－（0/3） Damage－（0/3）18

CEM43ºC value for low level and long time exposure condition

Exposure Condition CEM43ºC [min]75 GHz, 150 mW/cm2, 6 min. 22.2 min75 GHz, 50 mW/cm2, 6 min. 0.0005 min, ,75 GHz, 50 mW/cm2, 30 min. 0.004 min

-21< CEM43ºC < 40 min: Acute and minor damage-41< CEM43ºC < 22000 min: Acute and significant damage-41< CEM43 C < 22000 min: Acute and significant damage-22000 < CEM43ºC : Severe damage.

１９

Exposure conditions in this experimentEyelids held open by tape

Ocular damage was induced by beyond threshold exposure(Ex. 75 GHz 150 mW/cm2 6 min 1 day after exposure)

Rabbits’ inter-blink periodExposed eye Non-exposed eye

It is reported between 6.3 - 20 min. Our experimental condition, eyelidsopen for 6 min, was not harsh for the cornea. (No ocular damage wasobserved in the contralateral eye.)observed in the contralateral eye.)

２０

Sham Exposure (30 min) and /or +infrared exposure

Sham Exposure IR Exposurep

21

Sham Exposure (30 min.) /+IR

Sham Exposure Sham +IR

Before Exposure Before Exposure

32.5°C 32.7°C

p p

0.36 0.36 0.360 36 0 36 0 370.36 0.36 0.37

33.9ºC (1.4ºC↑) 37 8 ºC(5 1°C↑)( ↑) 37.8 ºC(5.1 C↑)

Immediately after Immediately after exposure exposure

0.23 0.26 0.35 0.26 0.28 0.2922２２

Sham Exposure (30 min) / +IR1 d ft1 day after

Sham Exposure Sham + IR

( )

0.37 0.35 0.360.37 0.35 0.36 0.37 0.45 0.360.37 0.45 0.36

0.35 0.33 0.35 0.38 0.48 0.41

Dry eye (corneal desiccation) does not cause corneal epithelial damage.D l h (IR MMW )Dry eye plus other stress (IR or MMW, etc.) induces corneal damage. 23

Exposure conditions (no aversive behavior control)(no aversive behavior control)

Eyelids not restrainedEyelids not restrained

Eyelid edema occurs but no ocular damageBefore exposure After exposure

Eyelid edema occurs, but no ocular damage(Ex. 75 GHz 150 mW/cm2 6 min 1 day after exposure)

Exposed eye Non exposed eye

No aversive behavior controlWith no control of aversive behavior ocular damage

Exposed eye Non-exposed eye

With no control of aversive behavior, ocular damagethreshold is determined by the skin hazard threshold.

２４

Comparison of eyelid and other skin

75 GHz 150 mW/cm2 6 min before exposure75 GHz 150 mW/cm 6 min before exposure

32℃ 30.5℃

75 GHz 150 mW/cm2 6 min 1 day after exposureEye Skin

75 GHz 150 mW/cm 6 min 1 day after exposure

53℃ 52.8℃

25

53Eye Skin

Investigation of ocular damage threshold by millimeter wave exposure … · ·...

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