Intraocular Smokeless Gunpowder Pellet from Explosion of .22 Caliber Bullet

Intraocular Smokeless Gunpowder Pellet from Explosion of .22 Caliber Bullet

Corresponding author: Dr. Craig M. Greven MD, 336-716-4091, Wake Forest University Eye Center, Medical Center Blvd, Winston-Salem, NC 27157-1033, USA. Tel: 336-716-4091; Email: cgreven@wakehealth.edu

Abstract

Background: In addition to the projectile (bullet), the propellant may also cause penetrating injuries to the eye. Orbital CT scan is believed to be the preferred method for imaging intraocular smokeless gunpowder. Our objective was to evaluate the applicability of B scan in detecting an intraocular foreign body.

Methods: This is a case report of a single patient who was evaluated after injury to his face and eyes from an ammunition explosion in close proximity to his face.

Results: The patient was found to have a smokeless gunpowder particle in the anterior vitreous that was not visible on orbital CT, but was discovered on B-scan ultrasound of the globe.

Summary: We present a single case report of a 15 year old male who was hit in the face and eye with a spray of debris from an exploding bullet. Two orbital CT scans (the current standard for assessing for intraocular smokeless gunpowder) were negative for intraocular foreign body; however B-scan ultrasound revealed a pellet, later determined to be smokeless gun- powder in the anterior vitreous of the right eye. Henceforth, this case report demonstrates the applicability of b scan ultra- sound in detecting intraocular smokeless gunpowder even in instances when orbital CT scans are negative for an intraocular foreign body.

Conclusion: This case report demonstrates the applicability of b scan ultrasound in detecting intraocular smokeless gun- powder even in instances when orbital CT scans are negative for an intraocular foreign body.

Keywords: Intraocular Foreign Body; Smokeless Gunpowder Pellet; Ocular B Scan Ultrasound

Introduction

Smokeless gunpowder pellets are only rarely reported as intraocular foreign bodies (Belkin and Ivry [1], Kotagiri et al [2], Amin and Keenan [3]). The 2 main constituents of gunpowder, nitrocellulose and nitroglycerin, are relatively insoluble in water and vitreous, decay slowly, and are gen- erally well tolerated in the eye and orbit ( [1,2] White et al

[4]). Therefore it is common practice to forgo surgical inter- vention in cases of intraocular smokeless gunpowder unless there is retinal or lenticular damage [2,3]. Detecting smoke- less gunpowder in the eye can be challenging as the parti- cles are relatively radiolucent. Amin et al reported that these particles are often undetectable on x-rays and B-scans, but that CT scans can be a relatively reliable method of detecting them [3].

We report the case of a 15 year old male who was hit in the face and eye with a spray of debris from a bullet that evaluates the applicability of B scan ultrasound in detecting intraocular smokeless gunpowder.

Methods

This is a retrospective, descriptive study, a single case report of a patient seen in a tertiary care eye center in the south-eastern United States. A 15 year old Caucasian male struck a round of

.22 caliber ammunition with a hammer, showering his face with gunpowder debris while the bullet itself fortunately missed him. He reported immediate stabbing pain and decreased vi- sion in his right eye. The patient was initially evaluated in an outside emergency department where he had a non-contrast maxillofacial CT with 1.5mm cuts that showed no intraocular foreign body (IOFB) or radioopaque orbital foreign body. His initial visual acuity at presentation was 20/25+ OD and 20/20 OS with IOP of 14 OD and 9 OS and full motility OU. His pupils were reactive OU with no APD but the right pupil had an irreg- ular in shape. External examination showed multiple foreign bodies embedded in the facial skin, most densely on the right side. Slit lamp exam revealed multiple areas of sub-conjunc- tival hemorrhage in the right eye. The cornea in the right eye had multiple epithelial defects with underlying circular areas of endothelial haze along with a single 2mm full-thickness cor- neal laceration in the mid-periphery at the 2 o’clock position that was Siedel negative. The iris in the affected eye showed signs of trauma at the 2 o’clock position with underlying lens opacity and presumed disruption (Figure 1). A dilated fun- duscopic examination showed a clear vitreous and no signs of trauma to the optic disc, macula, or retinal periphery and no foreign body were evident. (Figure 2)

Figure 1. Slit-lamp photograph of the injured right eye showing a cor- neal laceration, disruption of the iris and lens capsule, and lens opaci- fication suggestive of entry of an intraocular foreign body.

There was a high suspicion for an IOFB despite the negative

initial CT, as the anterior segment findings on the slit lamp

examination suggested an entry wound. A second CT of the orbits was performed with 2.5mm slice thickness and recon- structed to 1.25mm slice thickness to specifically evaluate for any IOFBs. This scan was also negative for any radiopaque for- eign body.

Figure 2. external photograph that illustrates the scatter of explosive debris across the right side of the patient’s face.

However, a B-scan ultrasound showed a sonodense foreign body in the anterior vitreous just posterior to the lens in the right eye (Figure 3). The patient was placed on oral ciproflox- acin as well as topical moxifloxacin, prednisolone, and cyclo- pentolate with close follow up pending planned lensectomy with possible pars plana vitrectomy and IOFB removal.

Figure 3. B-scan of right eye showing hyperechoic intravitreal foreign body, which was not visible on previous CT imaging studies.

Surgery was performed 3 days following the injury. An anteri- or approach by a cataract surgeon was planned under general anesthesia, with a retinal surgeon standing by. A continuous

tear anterior capsulorhexsis was performed, as the entry per- foration of the anterior capsule was relatively central and was able to be included in the capsulorhexis. The soft cataractous lens was easily aspirated, revealing a 2mm circular hole in the posterior capsule, with a small pellet shaped IOFB in the anterior vitreous just beneath (Figure 4). With minimal de- pression of the posterior capsule, the IOFB floated anteriorly through the posterior capsular hole and was captured and re- moved. A small amount of vitreous was seen to come into the anterior segment through the posterior capsular hole, and an anterior vitrectomy was performed. An intraocular lens was successfully placed in the capsular bag without difficulty. The patient had an uneventful post-operative course with a final BCVA of 20/20. The IOFB was submitted to forensic pathology where it was identified as a smokeless gunpowder pellet mea- suring less than 0.1cm (Figure 5).

Figure 4. Intraoperative photograph showing the circular foreign body (big arrow) just behind the posterior capsule. At this point in the procedure, the cataractous lens had been removed and the cap- sular bag is gently being expanded with viscoelastic. Note the edges of the anterior capsule rent from the entry of the projectile (small ar- rows). The small circular posterior hole in the posterior capsule is not visible in this photograph.

Discussion

Previous literature has suggested that CT imaging is the most reliable method of detecting smokeless gunpowder IOFBs [3]. This case demonstrates a patient with smokeless gunpowder IOFB in the anterior vitreous which was not detected by two CT scans but was identified on B-scan ultrasound. There are several features of this case that may help to explain why B scan ultrasound was more sensitive than CT imaging. First, the particle was quite small, measuring less than 1mm in size, which may have made its detection by CT imaging difficult. Also, the location of the IOFB in the anterior vitreous, away from the sclera may have aided in its identification by ultra- sound. While CT scan may be able to detect most IOFBs of this variety, B-scan ultrasound should be considered in cases where there is a high suspicion of a retained IOFB. This case also illustrates the importance of maintaining a high suspicion of an IOFB even when the bullet misses, in instances where there is scattered propellant or other debris in the periocular area of the face.

Figure 5. Photograph of IOFB after extraction from patient’s right eye.

References
  1. Belkin M, Ivry M. Explosive Intraocular Foreign Bodies. American Journal of Ophthalmology 1978, 85(5 pt 1): 676-678.
  2. Kotagiri AK, Sundaram V, Khandwala M, Teimory M. Gunpowder injury to the eye. Clinical and Experimental Ophthalmology. 2008, 36(2): 190-199.
  3. Amin K, Keenan J. Ocular Gunpowder Injury. Eye. 2007, 21:119-120.
  4. White WN, Preston R, Morgan CM, Kincaid MC. Retained Ocular Gunpowder. American Journal of Ophthalmology. 1988, 106(6): 762-763.

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