Mechanism and Emergency Management of Blast Eye/Orbital Injuries

Sabri T Shuker

Disclosures

Expert Rev Ophthalmol. 2008;3(2):229-246. 

In This Article

Applicable Orbital/Ocular Anatomy

The special eye position due to the architecture of the middle part of the facial skeleton extends laterally, exposing the surface of the eye/orbit to the blast injury. Multiple biophysics effects of blast waves demonstrate how blast affects individual tissues as a result of their vibratory energy and why some anatomical tissue are more susceptible to primary blast. The interaction of a high-frequency stress wave and a lower frequency shear wave determines the degree to which organs are damaged by dynamic pressure changes at tissue-density borders.

The ocular/orbital encloses vital anatomical organs (eyeball, muscle, fat, vessels, nerve tissues are enclosed by thin bone plates) containing (air–fluid–soft tissue medium) a unique interface for a shock wave to spread through to the surrounding medium related to the eye globe and orbital anatomical tissues.

The orbital walls consists of thin plates that separate orbital tissue content from the CSF and brain superiorly, the para nasal sinuses medially and inferiorly, and the lateral plates in the temporal region. Only the circumferential orbital rim is a thick resilient bone. The lateral wall has the lowest frequency of injury of all civilian facial fractures. The medial wall is of critical importance during blast implosion of the ethmoidal air cells in the medial wall, as it is composed of thin bones ranging from 0.2 to 0.4 mm in thickness close to the thin cribriform plate that leads to crush injury by blast effect into nasal–orbital–ethmoidal (NOE) comminuted fractures. The superior wall is moderately resistant to fracture; the orbital roof is 3 mm thick in the posterior and is thinnest just behind the superior rim in the anterior. The inferior wall is the most vulnerable to injury (Takashima [1999][103]).

Orbital volume is approximately 35 cc, of which only 7 cc (20%) is occupied by the eyeball. The remaining 28 cc contains muscles, nerves, fat, glands and blood vessels.[19,20] The orbit can thus have room for a compressible mechanism and accommodate a relatively large foreign body without showing great disturbance of function.[21] The distance from the eyeball to the medial, orbital wall (6.5 mm) is slightly larger than the distance to the lateral wall (4.5 mm).[17] Medially penetrating objects will injure the eyeball less frequently than an object entering laterally.[22]

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