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William Eric Sponsel, Matthew Aaron Reilly, Brian J Lund, Walter Gray, Richard Watson, Sylvia Linner Groth, Randolph D Glickman, Kimberly Thoe, SLOT (Sublethal Ocular Trauma); Anatomical Manifestations of Primary Blast Ocular Trauma Observed in an Ex Vivo Porcine Model. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4445.
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© ARVO (1962-2015); The Authors (2016-present)
To qualitatively describe the anatomic features of primary ocular blast injury observed using an in vitro porcine eye model. Porcine eyes were exposed to various levels of blast energy to determine the optimal conditions for future testing.
Fifty-three (53) enucleated porcine eyes were studied; 13 control eyes and 40 test eyes exposed to a range of blast overpressure levels. Eyes were pre-assessed with B-scan and UBM ultrasonography, photographed, mounted in gelatin within acrylic orbits, and monitored with high-speed videography during blast-tube impulse exposure. Post-impact photography, ultrasonography, and histopathology were performed and ocular damage was assessed. Injury scoring in each zone followed a new clinically relevant Composite Injury Scale addressing the practical needs of those engaged in the treatment of ocular injury or development of protective eyewear. Injury scores were ascribed on the basis of a stepwise algorithm to integrate the structural damage in each of the Zones 1-3 as defined by Pieramici et al (AJO 1997), where Zone 1 is the external ocular surface, Zone 2 the anterior chamber, and Zone 3 the internal posterior segment.
Strong evidence for primary blast injury was obtained. Common findings included angle recession, internal scleral delamination, cyclodialysis, peripheral chorioretinal detachments, and radial peripapillary retinal detachments. No full-thickness openings of the eyewall were observed in any of the eyes tested. Scleral damage demonstrated the strongest associative tendency for increasing likelihood of injury with increased overpressure. Table 1 shows the association between primary blast peak overpressure levels and the tendency for damage to structures in anatomic Zones 1-3. Note that a level 2 injury as referred to in the table is one that would require surgery to repair and would result in chronic pathology.
These data provide convincing evidence that primary blast can produce clinically significant ocular damage in the absence of particle impact. We also present a new Cumulative Injury Score indicating the clinical relevance of observed injuries.
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