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Invest Ophthalmol Vis Sci. 2018 Jan 1;59(1):349-361. doi: 10.1167/iovs.17-21530.

Long Term Temporal Changes in Structure and Function of Rat Visual System After Blast Exposure.

Author information

1
Department of Mechanical Engineering, University of Utah, Salt Lake City, Utah, United States.
2
Department of Bioengineering, University of Utah, Salt Lake City, Utah, United States.
3
Department of Ophthalmology & Visual Sciences, University of Utah, John A Moran Center, Salt Lake City, Utah, United States.

Abstract

Purpose:

We identify long-term ocular sequelae subsequent to experimental blast exposure.

Methods:

Male Long-Evans rats were exposed to 230 kPa side-on primary blast overpressure using a compressed air driven shock tube. Visual system function and structure were assessed for 8 weeks after exposure using optokinetic nystagmus and optical coherence tomography. Vitreous protein expression and histology (TUNEL, H&E) were performed at 1 day and 1, 4, and 8 weeks. IOP was recorded bilaterally during blast in a subset of animals.

Results:

Blast pressure profiles resembled the Friedlander waveform indicative of an open field blast. Peak IOP in directly-exposed eyes (240 kPa) was similar to peak blast overpressure, but IOP in indirectly-exposed eyes was 30% lower. Contrast sensitivity of blast-exposed animals decreased significantly by 20% 1 day after blast and did not recover by 8 weeks. Significant swelling and structural damage to the corneal epithelial and stromal layers were observed 2 weeks after blast exposure. Swollen corneas increased 254 ± 143 μm from baseline by 6 weeks, and scarring developed by 8 weeks. Histology revealed additional lens pathology 1 week after blast, suggestive of cataract development. Endothelial cell density increased significantly in blast-exposed animals between 1 and 4 weeks. Neurofilament heavy chain significantly increased after blast and returned to near baseline values by 8 weeks. Inflammatory cytokine changes corroborated ocular pathology findings.

Conclusions:

These data demonstrate immediate visual dysfunction and biochemical responses, but delayed structural pathology, in response to single primary blast exposure. The delayed pathology time course may provide a window to implement treatment strategies for improved visual outcome.

PMID:
29346495
DOI:
10.1167/iovs.17-21530
[Indexed for MEDLINE]

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