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INTRODUCTION

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The personal tragedy and economic loss associated with impaired vision or even blindness as a result of occupational eye injuries can be prevented by identifying workers at risk and instituting appropriate safety programs. Proper maintenance of tools and equipment by the employer and effective use of protective devices, such as safety glasses or face shields, by the employee will reduce the number of injuries, such as ocular contusions, trauma as a consequence of penetrating and nonpenetrating foreign bodies, conjunctival and corneal abrasions, lid lacerations, and optic nerve damage.

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Recognition of the toxic effects of chemical agents and protection from those that may be splashed into the eyes are vital for prevention of visual damage. The ready availability of facilities for cleansing and irrigation of the face and eyes in the workplace is of the utmost importance because initial steps for treatment of chemical burns—especially those caused by strong alkalis and acids—must be carried out immediately by the employee, fellow workers, or anyone else near at hand. There is no time to wait for specialized medical care, so employee education programs for emergency care of chemical burns are essential.

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The risks of ocular damage for x-ray technicians, glassblowers, welders, and other workers exposed to ionizing, infrared, and ultraviolet radiation have long been known, but damage caused by exposure to excessive amounts of visible light has been recognized only recently. Wearing protective lenses that filter the most offending wavelengths of visible light may become commonplace in the future.

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ANATOMY & PHYSIOLOGY

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A brief review of ocular anatomy and function will help in understanding the mechanisms of several kinds of eye injuries and how they affect the visual system (Figure 12–1). The orbit, eyelid, and conjunctiva are protective mechanisms for the eye. The orbit and its bony rim offer excellent mechanical protection from injuries, with the exception of those coming from the direct anterior or temporal directions. The eyelid and conjunctiva are essential for normal maintenance of the smooth, moist, clear anterior surface of the cornea, which, in turn, is essential for clear vision. The normal blinking mechanism depends on the third cranial nerve to open the lids and the seventh cranial nerve to close them. Moistening of the conjunctiva by lacrimal fluid depends in part on activation of the reflex arc between the sensory fifth innervation of the anterior eye and the parasympathetic secretomotor fibers that accompany the seventh cranial nerve along the petrous temporal bone into the middle fossa and then through the orbit to the lacrimal gland. Moistening of the corneal epithelium is aided by mucus from the goblet cells of the conjunctiva, particularly those on the tarsus of the upper lid. Reflex tear production by the lacrimal gland helps to dilute and wash away irritating substances that find their way into the conjunctival sac. The rich blood supply of the conjunctiva and lid also helps in ...

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