Vulnerability of the Retina to Injury from a Military Ruby Rangefinder at Battlefield Distances

Abstract

This study investigates the possibility of causing a vitreal hemorrhage with a standard ruby rangefinder at battlefield engagement distances when the laser is observed with the naked eye or through magnifying optics or filters. The experiments were undertaken on the eyes of anesthetized pigs. The pigs were anesthetized with Mebumal and given 0.5% thropicamid in the eyes. They were then exposed to the radiation from a standard military ruby rangefinder (pulsewidth 25 ns, pulse energy 180 mJ). The rangefinder was aligned with a He-Ne laser and a beamsplitter. Eight experiments were performed, each with several exposures. The range was varied from 0.5-850 m. Some of the experiments were made using the naked eye, some with a filter, some with binoculars (7 x 50) and some with a combination of filter and binoculars. The pulse energy was varied from 91-6500 muJ. Vitreal hemorrhages were caused at distances of 410 and 850 m when a pair of binoculars (7 x 50) was placed in front of the eyes. The intraocular energy varied between 1500 and 4400 microJ. Results indicate that there is a possibility of causing a vitreal hemorrhage in a soldier who is using standard field binoculars and looking in the direction of an ordinary military rangefinder at distances at least up to 850 m.

Vitreous Floaters Following Use of Dermatologic Lasers

“…Military range finders are similarly known to cause eye injuries in observers who are hundreds of feet away but inadvertently look in the direction of the laser 26 . Both Nd:YAG lasers and standard ruby lasers have been implicated, and in one study the eyes of anesthetized pigs, placed behind binoculars, developed vitreous hemorrhages when oriented in the direction of a range finder laser located 850 m (almost 1 km) away 27 . Intravitreal application of Er:YAG laser energy during eye surgery has also been associated with vitreous and retinal complications 28 .…”

“…26 Both Nd: YAG lasers and standard ruby lasers have been implicated, and in one study the eyes of anesthetized pigs, placed behind binoculars, developed vitreous hemorrhages when oriented in the direction of a range finder laser located 850 m (almost 1 km) away. 27 Intravitreal application of Er:YAG laser energy during eye surgery has also been associated with vitreous and retinal complications. 28 Even in the absence of specific injury, nonspecific heating induced by surgical Er:YAG lasers can alter vitreous conformation.…”

In vivo visualizing the dynamics of bone marrow stem cells in mouse retina and choroidal-retinal circulation

“…Retinal scarring, retinal traction, holes, and large scale photoreceptors loss can occur, depending on the characteristics of the laser beam, such as wavelength, pulse duration and energy, or beam power. (6,7). Photoreceptor cell death or damage resulting from a laser-induced retinal injury can lead to the permanent loss of vision, since photoreceptors, as part of the central nervous system, cannot be replaced.…”