• experimental
  
• epidemiological
  

Do you want to comment on the article?

Submit feedback

Medical/biological Study (experimental study)

Absence of corneal endothelium injury in non-human primates treated with and without ophthalmologic drugs and exposed to 2.8 GHz pulsed microwaves. med./biol.

PubMed Entry

Journal web site

Aim of study (according to author)
To study the effects of pulsed microwaves and the interaction of opthalmologic drugs (Timolol and Xalatan) on corneal endothelial damage in four adult Rhesus monkeys under anesthesia in order to confirm the results of previous studies (Kues et al. 1985 and Kues et al. 1992) reporting a microwave-induced corneal endothelial damage at a low threshold (2.6 W/kg). Additionally, previous studies reported that vasoactive ophthalmologic medications lowered the threshold by a factor of 10 to 0.26 W/kg.
Background/further details:
A nine-exposure regimen was selected for experiment I. Drug sensitization of microwave-induced corneal endothelial injury in experiment II (one year later) followed the three-exposure regimen of Kues et al. (Kues et al. 1992).
In Experiment I, ophthalmologic examinations were conducted before and 7, 30, 90, and 180 days after exposures. In Experiment II, ophthalmologic examinations were done 7, 30, 90, and 180 days after exposures.

Endpoint

• effects on eye: corneal endothelial damage

Exposure
General category: microwaves, PW (pulsed wave)

Field characteristics	Parameters
field 1: 2.8 GHz pulsed (PW) experiment 1 exposure duration: continuous for 4 hr/day, 3 days/week for 3 weeks	power: 29 W average over time power flux density: 13 mW/cm² average over time power flux density: 464 mW/cm² peak value power flux density: 14.2 mW/cm² average over time (at 20 cm from the pressure plate)
field 2: 2.8 GHz pulsed (PW) experiment 2 exposure duration: continuous for 4 hr/day on 3 days or 7 days	power: 29 W average over time power flux density: 13 mW/cm² average over time power flux density: 464 mW/cm² peak value power flux density: 14.2 mW/cm² average over time (at 20 cm from the pressure plate)

Exposed system:
animal (species/strain): Rhesus monkey (Macaca mulatta)
whole body exposure

Methods
Endpoint/Measurement parameters/Methodology

• effects on cardiovascular system: pulse rate
• thermoregulation: four skin temperatures at eyelid and rectal temperature
• others: effects on eye: corneal endothelial damage, endothelial cell density (as marker for damage), corneal thickness (specular microscopy)

Main outcome of study (according to author)
The microwave exposure resulted in a 1.0-1.2°C increase in eyelid temperature, but the absolute temperature never exceeded 38°C, a level well below the known damage threshold. Pulsed microwave exposure did not cause alterations in corneal endothelial cell density and corneal thickness with or without ophthalmologic drugs.
Therefore, the authors conclude that previously reported changes in the cornea exposed to pulsed microwaves were not confirmed at exposure levels that are more than an order of magnitude higher.

(Study character: medical/biological study, experimental study, full/main study)

Study funded by

• Office of Naval Research (ONR), USA

• Kojima M et al. (2009): Acute ocular injuries caused by 60-GHz millimeter-wave exposure.
• Kojima M et al. (2004): Influence of anesthesia on ocular effects and temperature in rabbit eyes...
• Elder JA (2003): Ocular effects of radiofrequency energy.
• Foster KR et al. (2003): Thermal modeling of millimeter wave damage to the primate cornea at 35 GHz and...
• Chalfin S et al. (2002): Millimeter wave absorption in the nonhuman primate eye at 35 GHz and 94 GHz.
• Ye J et al. (2001): Low power density microwave radiation induced early changes in rabbit lens...
• Lu ST et al. (2000): Effects of high peak power microwaves on the retina of the rhesus monkey.
• Kues HA et al. (1999): Absence of ocular effects after either single or repeated exposure to 10...
• Kues HA et al. (1992): Increased sensitivity of the non-human primate eye to microwave radiation...
• Kues HA et al. (1992): Microwave-induced changes to the primate eye.
• Kues HA et al. (1985): Effects of 2.45-GHz microwaves on primate corneal endothelium.
• Carpenter RL (1979): Ocular effects of microwave radiation.
• Guy AW et al. (1975): Effects of 2450-MHz radiation on the rabbit eye.