Classification of Ocular Trauma

CLASSIFICATION OF OCULAR TRAUMA

Sharath C. Raja and Dante J. Pieramici

The Ocular Trauma Classification Group has developed a classification system 1 based on BETT² (see Chapter 1) and features of globe injury at initial examination. Mechanical^a trauma to the eye is subdivided into open and closed globe injuries because these have different pathophysiological and therapeutic ramifications (Tables 2–1 and 2–2). The system categorizes trauma by four parameters:

1. Type, based on the mechanism of injury.^3–9 The type of the injury should be determined based on the history as reported by the patient or witnesses regarding the circumstances of the incident. If a patient is unconscious or unreliable (see Chapters 8, 9, and 30), typing may be based on clinical examination. If media opacity or other clinical factors preclude adequate examination, ultrasonography, x-ray, or CT scanning may assist.

2. Grade, as defined by visual acuity measurement at the initial examination.^3,4,7–16,b Testing may be done with a Snellen acuity chart or a Rosenbaum near card and should be performed with the patient’s corrective lenses if possible. A pinhole vision may be used if necessary.

3. Presence/absence of a relative APD.^3,17 The presence of an APD, as measured by the swinging flashlight test (see Chapter 9), is a gross indicator of aberrant optic nerve and/or retinal function. If the affected eye is nonreactive for mechanical or pharmacologic reasons, observing the consensual response in the fellow eye (i.e., looking for a “reverse” APD) is advised.

4. Extent (i.e., zone) of the injury: wound location in open globe injuries or the most posterior extent of damage in closed globe injuries.^{3–5,7,8,10,14–16} The zone of injury depends on whether the injury is open or closed globe.

PEARL… Precise determination of the zone of injury is frequently possible only after surgical exploration of the wound.

For open globe injuries, zone I injuries are confined to the cornea and limbus. Zone II injuries involve the anterior 5 mm of the sclera (i.e., not extending into the retina). Zone III injuries involve full-thickness defects whose most anterior aspect is at least 5 mm posterior to the limbus. In cases involving perforating injury, the most posterior defect, usually the exit site, is used to judge the zone of involvement.

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