UNDER THE MICROSCOPE
Dr. Raymund W. Lo
Lasers have been very much in the limelight since it was alleged that a Chinese Coast Guard ship trained a laser beam on a Philippine Coast Guard ship that was on a re-supply mission to the BRP Sierra Madre in the West Philippine Sea. This incident temporarily blinded its crew, according to the official press release.
The video shared online shows a rather big green laser beam being directed at the Philippine ship, although the Chinese embassy denies that it was a military-grade laser. This incident has triggered a diplomatic protest, and the Philippine government has summoned the Chinese ambassador to Malacañang to show its displeasure.
What is clear is that lasers, whether military-grade or not, are health hazards on humans and animals alike, mainly on the skin and the eyes. Thus, even laser pointers come with the admonition to never point them at people, especially the eyes.
According to the Princeton University Environmental Health and Safety, laser hazards are either beam- or non-beam-related. Beam-related “effects can range from mild skin burns to irreversible injury to the skin or eye. The biological damage caused by lasers is produced through thermal, acoustical, and photochemical processes.” The various ill-effects’ severity depends on several factors, including exposure duration, beam wavelength or energy, and the area or type of tissue exposed to the beam.
Since the Philippine crew experienced temporary blindness, this should have triggered a thorough check on their eyes as soon as they returned to port to document the permanent ill-effects, if any, the incident could have caused. It may also shed light on whether it was a military-grade laser that was used or not, since China has repeatedly denied its use of military-grade lasers. This has apparently not been done so far as press releases are concerned. It certainly can still be done by our well-trained ophthalmologists if the government will only signal for assistance in this international incident.
Damage to the eye by lasers can be on the cornea in the form of photokeratitis or corneal burn, with ultraviolet B and C rays and infrared B and C; on the lens as cataract formation with ultraviolet A and infrared A, B, and C radiation; and on the retina with burns by infrared A and B, and by visible light. If the laser burn occurs on the fovea centralis of the retina, which provides the most acute vision, it will result in permanent disability, since the affected person can no longer focus, effectively rendering that person legally blind. All he/she can discern is light and movement but not detailed images.
The eye does have a self-defense mechanism — the blink or aversion response, in which the person instantly turns away from a bright light source within a quarter of a second. This can defend the eye from damage when lower power lasers are used. However, with higher power lasers, damage can occur in less than the time the response occurs. Herein lies the objective distinction between a “hand-held greenlight pointer for navigation safety” and a military-grade laser.
Perhaps the Philippine Academy of Ophthalmology can lend a hand to our government officials who may not be aware of how to distinguish between military-grade lasers and other laser types. It definitely will bolster our government’s claims of a harassment and intimidation by the Chinese Coast Guard if it can establish any form of eye damage in the concerned Coast Guard crew. Prima facie evidence is needed. That’s how to get it.