Effects of intravitreal injection of siRNA against caspase-2 on retinal and optic nerve degeneration in air blast induced ocular trauma

Ocular repeated air blast injuries occur from low overpressure blast wave exposure, which are often repeated and in quick succession. We have shown that caspase-2 caused the death of retinal ganglion cells (RGC) after blunt ocular trauma. Here, we investigated if caspase-2 also mediates RGC apoptosis in a mouse model of air blast induced indirect traumatic optic neuropathy (b-ITON). C57BL/6 mice were exposed to repeated blasts of overpressure air (3 × 2 × 15 psi) and intravitreal injections of siRNA against caspase-2 (siCASP2) or against a control enhanced green fluorescent protein (siEGFP) at either 5 h after the first 2 × 15 psi ("post-blast") or 48 h before the first blast exposure ("pre-blast") and repeated every 7 days. RGC counts were unaffected by the b-ITON or intravitreal injections, despite increased degenerating ON axons, even in siCASP2 "post-blast" injection groups. Degenerating ON axons remained at sham levels after b-ITON and intravitreal siCASP2 "pre-blast" injections, but with less degenerating axons in siCASP2 compared to siEGFP-treated eyes. Intravitreal injections "post-blast" caused greater vitreous inflammation, potentiated by siCASP2, with less in "pre-blast" injected eyes, which was abrogated by siCASP2. We conclude that intravitreal injection timing after ocular trauma induced variable retinal and ON pathology, undermining our candidate neuroprotective therapy, siCASP2.

Traumatic brain injury and sight loss in military and veteran populations- a review

War and combat exposure pose great risks to the vision system. More recently, vision related deficiencies and impairments have become common with the increased use of powerful explosive devices and the subsequent rise in incidence of traumatic brain injury (TBI). Studies have looked at the effects of injury severity, aetiology of injury and the stage at which visual problems become apparent. There was little discrepancy found between the frequencies or types of visual dysfunctions across blast and non-blast related groups, however complete sight loss appeared to occur only in those who had a blast-related injury. Generally, the more severe the injury, the greater the likelihood of specific visual disturbances occurring, and a study found total sight loss to only occur in cases with greater severity. Diagnosis of mild TBI (mTBI) is challenging. Being able to identify a potential TBI via visual symptoms may offer a new avenue for diagnosis.

The Impact of Combat Ocular Trauma and Traumatic Brain Injury on Vision- and Health-Related Quality of Life Among U.S. Military Casualties

PURPOSE

The purpose of this study was to assess visual and health-related quality of life (QOL) among U.S. military service members who sustained combat ocular trauma (COT) with or without associated traumatic brain injury (TBI).

METHODS

This was a single-center, prospective observational study of U.S. service members (n = 88) with COT who were treated at Walter Reed National Military Medical Center. Participants completed the National Eye Institute Visual Function Questionnaire (VFQ-25) at enrollment and at follow-up (>1 year) and supplemental surveys: Neurobehavioral Symptom Inventory, the Medical Outcomes 36-item Short Form Survey (SF-36), and Mayo-Portland Adaptability Inventory.

RESULTS

Initial and follow-up VFQ-25 showed a statistically significant increase in median scores for near activities (initial: 75.0, follow-up 83.3; P = .004) and peripheral vision (initial: 50.0, follow-up: 75.0; P = .009) and in composite scores (initial: 79.5, follow-up: 79.8; P = .022). Comparing those who did (n = 78) and did not (n = 8) have a TBI history, there were no significant differences in median change in VFQ-25 composite scores (with TBI: 2.3 vs. no TBI: 10.7; P = .179). Participants with a TBI history had a significantly lower median SF-36 General Health score (with TBI: 67.5 vs. no TBI: 92.5; P = .009).

CONCLUSIONS

Vision-related QOL of COT patients is generally good in the long term. However, those with both COT and a history of TBI conditions showed significantly worse functioning in several domains than those without TBI. As TBI is a common finding in COT, this association is an important factor impacting this population's overall clinical presentation and daily functions.

Perforating ocular trauma due to shotgun pellet - Clinical profile and visual outcome

Purpose:

The aim of this study was to determine visual and anatomical outcome of perforating injuries due to shotgun pellet.

Methods:

This was a prospective observational study carried out between July 2016 and Jan 2019 at a tertiary care referral center in Srinagar, Jammu and Kashmir. A total of 172 eyes with perforating injuries of 170 patients were included in the study and were followed up for 6 months with best-corrected visual acuity, slit-lamp examination for status of anterior chamber and lens, fundus examination for status of retina and media, intraocular pressure measurements, and OCT (optical coherence tomography) and FFA (fundus fluoresceine angiography) in selected cases. The relative improvement of visual acuity after treatment was interpreted by applying paired two-tailed t tests. Prognostic significance of other variables was calculated using Chi-square and Chi-square for linear trend tests, for two dependent outcome variables of good outcome and poor outcome.

Results:

WHO category 4 visual impairment was found in 66 (38.4%) eyes, whereas category 0 was found in 24 (14%) of eyes. Retina was found to be attached 99 (57.6%) of study eyes.

Conclusion:

Perforating injury is a severe form of ocular trauma with grave consequences in terms of functional and anatomical outcome.

War-related ocular injuries in Damascus during the Syrian Crisis

BACKGROUND

. Ocular injuries constitute a major cause of visual morbidity, and they have a significant socioeconomic impact worldwide. We aimed to document the types and causes of Syrian War related ocular injuries in Damascus, Syria.

METHODS

. Medical records were retrospectively reviewed to evaluate all patients in Al-Mouwasat University Hospital and Damascus Hospital, whose ocular injuries were caused by war-related activities during the period extending between January of 2016 and December 2017.

RESULTS

. 150 eye injuries in 127 patients were reviewed, in which 46 (31%) were bilateral and 87 (58%) were open globe injuries. The leading cause of the observed ocular injuries was improvised explosive devices (IED) [37 eyes (41%)]. The majority of patients presented with an initial best corrected visual acuity (BCVA) of "light perception" (LP) to "hand movement" (HM) [51 eyes (34%)]. Information on the final BCVA was available for 69 injured eyes only, and it was "no light perception" (NLP) in 20 eyes (29%).

CONCLUSION

. Explosive weaponry is the main culprit in most war-related ocular injuries in Syria. The high incidence of open globe injuries caused many of the cases to be severe in nature. Education on the precautionary measures that protect the eyes such as the use of combat eye protection during wartimes ought to be enforced, so that future ocular injuries can be prevented.

Blunderbuss: Ocular and Orbital Injuries Due to Muzzle-Loading Firearms

PURPOSE

Injury to the eye and/or orbital and adnexal structures associated with antiquated muzzle-loading firearms has not, to our knowledge, been characterized with the exception of a single case report.

METHODS

A retrospective chart review of 7 patients treated at Vanderbilt University Medical Center from 2003 to 2017 who sustained traumatic injuries to the ocular and/or orbital structures secondary to the discharge of muzzle-loading firearms. The study was approved by the Vanderbilt Institutional Review Board.

RESULTS

In 6/7 cases, injuries occurred secondary to the muzzle-loading firearm exploding due to dysfunction or misuse. Foreign material deriving from the firearm was retained in 3/7 patients. Initial examination of the orbit and adnexa revealed 5/7 individuals sustaining orbital fractures and 6/7 with facial lacerations (including 2 with eyelid lacerations); none had evidence of a lacrimal duct injury. Three patients suffered globe injuries (1 closed-globe and 2 open-globe). Visual acuity at last follow-up was ≥20/20 in 12/14 eyes examined. Surgical intervention was required in the treatment of 4/7 individuals (including 3/7 requiring intervention for sustained orbital fractures). No individuals were wearing eye protection at the time of injury. All individuals survived their injuries.

CONCLUSIONS

The operation of muzzle-loading firearms poses a unique risk of injury to the operator. The resultant injuries in this case series were primarily due to the explosion of the firearm, which subsequently appear similar to orbital and ocular blast injuries caused by explosive weapons. Orbital injuries and more potentially more devastating ocular injuries may have been prevented by protective eyewear.

Assessment of necroptosis in the retina in a repeated primary ocular blast injury mouse model

Primary blast injury (caused by the initial rapid increase in pressure following an explosive blast) to the retina and optic nerve (ON) causes progressive visual loss and neurodegeneration. Military personnel are exposed to multiple low-overpressure blast waves, which may be in quick succession, such as during breacher training or in combat. We investigated the necroptotic cell death pathway in the retina in a mouse repeated primary ocular blast injury (rPBI) model using immunohistochemistry. We further evaluated whether intravitreal injections of a potent necroptosis inhibitor, Necrostatin-1s (Nec-1s), protects the retina and ON axons by retinal ganglion cells (RGC) counts, ON axonal counting and optical coherence tomography (OCT) analysis of vitreous haze. Receptor interacting protein kinase (RIPK) 3, increased in the inner plexiform layer 2 days post injury (dpi) and persisted until 14 dpi, whilst RIPK1 protein expression did not change after injury. The number of degenerating ON axons was increased at 28 dpi but there was no evidence of a reduction in the number of intact ON axons or RNA-binding protein with multiple splicing (RBPMS)⁺ RGC in the retina by 28 dpi in animals not receiving any intravitreal injections. But, when intravitreal injections (vehicle or Nec-1s) were given there was a significant reduction in RBPMS⁺ RGC numbers, suggesting that rPBI with intraocular injections is damaging to RGC. There were fewer RGC lost after Nec-1s than vehicle injection, but there was no effect of Nec-1s or vehicle treatment on the number of degenerating axons. OCT analysis demonstrated no effect of rPBI on vitreous haze, but intravitreal injection combined with rPBI increased vitreous haze (P = 0.004). Whilst necroptosis may be an active cell death signalling pathway after rPBI, its inhibition did not prevent cell death, and intravitreal injections in combination with rPBI increased vitreous inflammation and reduced RBPMS⁺ RGC numbers, implying intravitreal injection is not an ideal method for drug delivery after rPBI.

Indirect Traumatic Optic Neuropathy Induced by Primary Blast: A Fluid–Structure Interaction Study

Current knowledge of traumatic ocular injury is still limited as most studies have focused on the ocular injuries that happened at the anterior part of the eye, whereas the damage to the optic nerve known as traumatic optic neuropathy (TON) is poorly understood. The goal of this study is to understand the mechanism of the TON following the primary blast through a fluid–structure interaction model. An axisymmetric three-dimensional (3D) eye model with detailed orbital components was developed to capture the dynamics of the eye under the blast wave. Our numerical results demonstrated a transient pressure elevation in both vitreous and cerebrospinal fluid (CSF). A high strain rate over 100 s−1 was observed throughout the optic nerve during the blast with the most vulnerable part located at the intracanalicular region. The optic nerve deforming at such a high strain rate may account for the axonal damage and vision loss in patients subjected to the primary blast. The results from this work would enhance the understanding of indirect TON and provide guidance in the design of protective eyewear against such injury.

Ophthalmic Injuries Related to Maxillofacial Trauma Due to Urban Warfare

: Midfacial trauma commonly causes ocular injuries of varying degrees. Eye injuries account for approximately 10% of all battle injuries. Severity of injuries may range from a subconjunctival haemorrhage to optic nerve injury and globe laceration and rupture.

AIM OF STUDY

Is to evaluate the associated ophthalmic injuries in maxillofacial trauma due to war and to emphasize the need for proper ophthalmic examination to exclude and manage any associated ophthalmic injuries.

MATERIALS AND METHODS

A total of 66 patients with maxillofacial trauma due to war were considered in this study and underwent classification of the fractures to know patterns of fractures and to specify the ophthalmic injuries which might be associated with each fracture. Referral to ophthalmologist was considered to determine the exact nature of ophthalmic injuries. Results by a maxillofacial surgeon and ophthalmologist were evaluated.

RESULTS

Midfacial trauma particularly those associated with zygomatic bone fracture was highly significant due to blast and bullets can lead to serious ophthalmic injuries. This was related to 57% of ophthalmic injuries. The related ocular injuries which were subconjunctival hemorrhage and the rupture or lacerated eye globe found to be highly significant war injuries while the preretinal hemorrhage and diplopia were significant.

CONCLUSION

A thorough proper ophthalmic examination should be carried out for every patient with these fractures and suspected cases should be placed under close observation so that immediate and active treatment can be taken if necessary.

The role of computerised tomography in predicting visual outcome in ocular trauma patients

PURPOSE

Ocular blast injuries in the military setting are particularly associated with significant maxillofacial trauma and/or brain injury. The opportunity to perform a comprehensive ophthalmic evaluation is frequently limited in the acute multiple trauma scenario. We aim to describe the relationship between the clinical effects of acute ocular and orbital blast trauma with the findings on computerised tomography (CT).

METHODS

This was a retrospective consecutive case series of all soldiers with facial and/or suspected ocular injuries. A total of 80 eyes that had suffered blast injuries of varying severity were studied. Assessment of orbital and ocular CT images were performed by military consultant radiologists. A comparison was made with actual clinical findings. Statistical analysis was performed using Fisher's exact test.

RESULTS

No pathological findings were described in 37 of the 80 eyes imaged by orbital and ocular CT scans. Clinically, these eyes and orbits were all found to be intact, or had minor trauma. All foreign bodies and penetrating eye injuries were successfully diagnosed by CT. Absence of an orbital fracture did not rule out a globe injury. However, a corneal or scleral defect was less likely when an orbital fracture was absent.

CONCLUSION

The eye is a delicate structure prone to injury that requires urgent repair if breached. It is difficult to assess thoroughly in the unconscious or distressed patient. In this context, CT imaging is invaluable to be able to make a relatively confident prediction of clinical findings and decide upon the necessity for acute ophthalmic surgical intervention.