Prevention and Medical Management of Laser Injuries FM 8-50

PREFACE Purpose and Scope

This field manual provides basic preventive, protective, and diagnostic information on laser injuries. The treatment procedures described herein are for use by combat medics, battalion aid station personnel, and other medical treatment facilities without an Ophthalmologist.

Also, an evaluation matrix is provided for use by combat lifesavers and combat medics. Once an individual has been diagnosed as having a severe laser injury, causing loss of vision, he will be prepared for evacuation to a medical treatment facility where he can receive specialized care for his injury.

1. Introduction

a. The word “laser” is an acronym for “light amplification by stimulated emission of radiation.” In common usage, a laser is a device that produces an intense, narrow beam of light. Normally each laser can only produce a single frequency or color of radiation. However, there are many different types of lasers. Some produce light which is in the visible portion of the radiation spectrum and, therefore, can be seen. Others produce radiation which is outside of the visible spectrum (either infrared or ultraviolet) and is, therefore, invisible. Appendix A depicts the wavelength of common lasers. Some laser devices produce radiation with sufficient energy to severely injure or burn the eyes or skin of personnel who are down range. The use of laser devices, such as rangefinders and target designators may result in accidental injury to the eye. Appendix A also depicts some of the lasers commonly found in the United States Army. It is possible that similar devices may be used by opposing forces as antipersonnel weapons.

b. The beam of light emitted from a laser device is normally very narrow, usually less than an inch in diameter. However, over long distances, the beam progressively becomes wider. For a military laser, the beam is typically 1 meter in diameter at a distance of 1 kilometer and 2 meters in diameter at a distance of 2 kilometers. Thus, a laser can irradiate the whole body at these distances. If the energy of the laser is high enough, such exposures could burn clothing, skin, or any part of the body exposed to the beam. Most lasers, however, are not powerful enough to generate burns. Because the eye focuses and concentrates whatever light that enters the eye, it is extremely sensitive to injury from almost any type of laser device. The concentration of energy which is focused onto the back of the eye can be 100,000 times greater than the energy which enters at the front of the eye. Thus depending upon the type of laser, the energy output of the laser, and the distance from the laser, a spectrum of injuries can be expected. These may range from very tiny lesions in the back of the eye to severe burns affecting vast portions of the body. See Appendix A for principal wavelengths of common lasers.

c. Injuries to the eye result when the energy from the laser is absorbed by various anatomical structures. The frequency of the laser radiation determines which structure absorbs the energy (Figure 1).

(1) Ultraviolet. Lasers operating in the ultraviolet spectrum (below 400 nm UV-A,B,C) are absorbed in the anterior segments of the eye, primarily by the cornea, as well as by the lens.

(2) Visible. Laser radiations in the visible spectrum (400-700 nm) are absorbed primarily within the retina by the pigment epitheliums and the choroid.

(3) Infrared. Absorption of lasers in the infrared spectrum occurs in two areas of the eye. Lasers at the near-infrared spectrum (700-1400 nm IR-A) damage the retina and the choroid, whereas light in the far-infrared spectrum (above 1400 nm IR-B,C) damages the cornea.

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TABLE OF CONTENTS

Preface

Introduction

threat

Anatomy of the eye

Prevention/Protection

Laser Radiation Dose

Injuries

Symptoms

Physical findings

Evaluation of Suspected Laser Injuries

Treatment

Evacuation Criteria

Stress

Appendix A: Wavelenggths of Lasers

Appendix B: Combat Lifesaver and Combat Medic Laser eye Injury Evaluation Matrix

Glossary

References

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