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AMERICAN JOURNAL OF OPTHALMOLOGY Eye Injury Caused by Tear-Gas Weapons The potential hazard to the eye from tear gas weapons has not been fully appreciated. Scattered reports in the ophthalmic literature have mainly emphasized that the occurrence of such eye damage is rare and temporary and that full recovery should be anticipated. The great popularity of all sorts of teargas devices reflects this attitude. Possession of the tear gas pen has become particularly common, the purchase often being prompted by a need for a cancelable, inexpensive weapon for self defense. This need is quickly answered because tear gas pens often can be purchased at the nearby drugstore or through a mail order house. The availability of tear gas pens also reflects the notable absence of laws controlling the sales of these items to the public. In fact, sales and possession of tear gas pens are controlled mainly in New York, Illinois and California. Not surprisingly, therefore, the newspapers sporadically report the misguided use of a tear gas weapon by some misinformed and often irresponsible individual. We reviewed the cases on file in the Armed Forces Institute of Pathology (AFIP) involving eyes that had been enucleated following an injury by a tear gas weapon, considering the following points: (1) The medical literature does not emphasize the potential of a tear gas weapon to produce permanent sequelae, and, indeed, only four cases (l,3) have been described in which enucleation followed such injury; (2) the public and legal authorities regard exposure to tear gas only in terms of its transient incapacitating effects; and (3) because of its indiscriminate and widespread distribution among civilians, it is likely that injuries of the eye from tear gas weapons will be more frequently encountered in the future. The blast from a tear gas weapon, such as a tear gas pen, has three components: the propellant, the wadding, and the chemical agent. The propellant usually is a primer, gunpowder, or both, which generates the explosive charge that drives the tear gas from the cartridge. It therefore becomes part of the blast. The wadding is the disc that seals the outlet of the cartridge and may be made of rubber, cardboard, or synthetic material. Fragments of wadding also join the blast. The third component of the blast is the tear gas itself, and in most pens the chemical agent is in the form of a fine powder. Upon firing, a suspension of fine particles results, similar to an aerosol. Complete gaseous transformation may occur when the particles of the chemical agent become embedded in tissues, which may produce crepitation. Because of these various components, as well as the force of the blast, it is not strictly correct to refer to these cases as tear gas injuries. Many factors other than the tear gas, per se, may play a role in damaging the tissues. More precisely, these eyes have been damaged by a tear gas weapon of which the tear gas is only one of the potentially injurious factors. REVIEW OF CASES Our review of material from the files of the Armed Forces Institute of Pathology re vealed that 14 eyes of 13 men required enu cleation following injury by a tear gas were moved shortly after injury, revealing necro sis of the anterior segment, an intense necro tizing keratitis of varying degree, and an associated suppurative iridocyclitis. Un doubtedly these changes represented the acute chemical damage of tear gas. The after effects of the changes could be seen in several eyes that showed retrocorneal membranes and obliteration of the anterior chamber and chamber angle. The remaining nine eves were enucleated up to 15 years following injury, and the findings in these chronic cases can best be attributed to the sequelae of neuroparalytic kera topathy, probably related to the neurotoxic effects of tear gas. Another noteworthy findings was the presence of postcontusion deformities of the chamber angle probably caused by the effect of the blast or perhaps by fragments striking the eye. Various features of the tear gas weapon, such as the blast force, the propellant charge, the wadding, and age of the cartridge, in addition to the chemical agent itself, should be considered in evaluating such eyes either clinically or microscopically. One of these cases (AFIP 1222899) has been described previously. There were no cases involving women or children. Two of the men were soldiers at the time of injury, although in neither case divas the injury sustained in combat or in training maneuvers. In most instances the tear gas was discharged into the patient's face while he was examining a tear gas device, during an altercation, or while being apprehended by a lawenforcement officer. Many of the histories were incomplete, but in roughly half of the cases the injuries were self inflicted and accidental. In the remaining half, the weapon was fired by a second person with the intent to injure or disable. The clinical and pathologic observations could be divided into two groups, according to time of enucleation: Five eyes exhibiting acute changes were enucleated within two months after injury; nine eyes with chronic changes were enucleated from eight months to 15 years after injury. During the acute period the clinicians referred to the patients' intense ocular pain and described the corneas as being opaque, scarred, vascularized, and/or ulcerated. The contents of the anterior chamber were usually noteworthy, including pus, fibrin, blood, and/or debris. In a few cases glaucoma was apparent clinically. Since the ocular media were too opaque to permit ophthalmoscopic examination, the posterior segment was not described in any case. Microscopic examination of the five eyes enucleated during the acute period invariably revealed an intense, suppurative, necrotizing keratitis. The deeper aspects of the cornea often exhibited areas of coagulative necrosis, seen as zones of acellularity and total loss of keratocytic nuclei. These corneal changes were accompanied by a marked suppurative iridocyclitis, the anterior chamber usually being filled with pus and hemorrhagic debris. Organization of this inflammatory material was associated with shallowing of the anterior chamber, formation of retrocorneal membrane, and obliteration of the chamber angle by peripheral anterior synechias. In one case retrodisplacement of the iris root and a portion of the ciliary body was indicative of a concurrent contusion deformity of the chamber angle. In another instance the superficial cornea was thickened and replaced by a mantle of granulation tissue. More commonly, however, in most eves enucleated during the acute period, the reparative properties of granulation tissue could not compensate for the intense corneal necrosis. Therefore acute corneal ulcers were seen ill various stages, and in the roost extreme case a huge perforating defect was present in the cornea and adjacent sclera with prolapse and disorganization of the intraocular contents. This case was of particular interest because, in addition to the intraocular retention of foreign material with a granulomatous endophthalmitis, there were numerous nonvascular cystic spaces within the granulation tissue that filled the anterior segment. These spaces manrepresent the sites where penetrating particles of the chemical agent had undergone vaporization. In the absence of corneal perforation the posterior segment was often unremarkable except for the occasional presence of mild papilledema. The nine eyes encleated eight months to 15 years following injury could be differentiated from the previous group by their clinical and microscopic findings. Although one eye was enucleated following a perforating limbal wound and another because of accidental perforation during lamellar keratoplasty, the remaining eyes were enucleated as elective procedures because they were blind, unsightly, and exhibited a vascularizing keratitis often with ulceration and recurrent perforation. Microscopic examination confirmed these clinical observations and also revealed an associated iridocyclitis of the suppurative and nongranulomatous variety together with postnecrotic scarring of the iris and ciliary body. The most dramatic changes, however, were seen in four eyes, each of which revealed an indolent perforated corneal ulcer. Chronicity of the ulcer was reflected by epithelial proliferation along the edges and base of the defect often with extension into the anterior chamber. There was marked disorganization of the anterior segment with total collapse of the anterior chamber and formation of broad anterior synechias. A lens remnant could be found in only one of the four eyes. Advanced degeneration of the posterior segment was also present, with detachments of the retina and choroid and vascularization of the vitreous body. Chronic corneal perforation was not a feature of the other five eyes removed during the chronic phase. Three of these eyes exhibited retrocorneal membranes, and one had an obvious deformity of the chandler angle with typical retrodisplacement of the iris root, caused by contusion. COMMENT A tear-gas weapon presents several dangers to the eye. The eye ma! be damaged by the shock force generated by the propellant charge for the chemical agent. It should be recalled that two enucleated specimens had obvious deformities of the angle from contusion. In addition, the burning residues of gunpowder or primer may strike the eye, inflicting a burn. Another source of damage consists of the fragements of wadding from the tear-gas pens. Metallic fragments from certain tear-gas munitions such as grenades may also cause injuries. Upon striking the cave, these fragments may be particularly destructive because they are often saturated with the chemical agent. Experimental studies. have revealed the remarkable penetrating capacity of the wads from a conventional tear-gas pen, and it was felt that a contusive injury above the afflicted eye represented the site of impact of the wading. A granulomatos endophthalmitis caused by retained foreign bodies was present in case 4, but the exact nature of the material could not be determined. The tear gas itself presents the greatest hazard to the eye. It may be composed of any one or a combination of related chemicals, all of which are potent lacrimators in minute concentrations. Chloroacetophenone (CN), the most common, is usually present Within the cartridge as a micropulverized powder that, upon firing, becomes a mist of finely suspended particles. Aging alters the physical characteristics of the chemical, with a tendency to form clumps or a solid mass. When expelled as a solid mass, the material acts as a lowvelocity missile, and by this means physical and mechanical factors may augment the inherent destructive capacity of the chemical. These factors probably explain how in one reported case the chemical agent penetrated the orbit, leading to a relentless necrosis of the orbital and facial bones. Attention has been drawn recently to the particular neurotoxic potential of CN. This report described three persons injured by accidental discharge of teargas pens into their hands. Following the injury there was prolonged and sometimes permanent anesthesia of portions of the hands and fingers. Microscopic examination revealed marked thickening of the epineurium and loss of axis cylinders. These morphologic observations are consistent with earlier biochemical studies (7,8) showing that CN reacts selectively with free sulfhydryl groups in proteins, causing an irreversible inhibition of enzymes containing sulfhydryl groups. The chemical action results particularly in denaturation of enzymes associated with sensory nerve activity.(9) This neurotoxic capacity may explain the unusual finding that half of the enucleationsin this series were performed three or more years after the original injury and that histologic examination of these perforating corneal ulcerations indicated they had persisted for an inordinately long time. It is very likely that these eyes, initially not damaged sufficiently to cause prompt enucleation, go on to develop neuroparalytic keratopathy with its sequelae. Similar observations (5,10) have been made clinically. SUMMARY This article reports findings from a study of 14 eyes enucleated following injury by a tear-gas weapon. Five of the eyes were removed shortly after injury, revealing necrosis of the anterior segment, an intense necrotizing keratitis of varying degree, and an associated suppurative iridocyclitis. Undoubtedly these changes represented the acute chemical damage of tear gas. The after effects of the changes could be seen in several eyes that showed retrocorneal membranes and obliteration of the anterior chamber and chamber angle. The remaining nine eves were enucleated up to 15 years following injury, and the findings in these chronic cases can best be attributed to the sequelae of neuroparalytic keratopathy, probably related to the neurotoxic effects of tear gas. Another noteworthy findings was the presence of postcontusion deformities of the chamber angle probably caused by the effect of the blast or perhaps by fragments striking the eye. Various features of the tear-gas weapon, such as the blast force, the propellant charge, the wadding, and age of the cartridge, in addition to the chemical agent itself, should be considered in evaluating such eyes either clinically or microscopically.
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