Birmingham Eye Trauma Terminology (BETT)
The BETT was created by Kuhn et al in 1996 to provide both a clear definition of all injury types and placing the injuries with a comprehensive framework.
Terms in the BETT
Eyewall- Sclera and Cornea
Though technically the eyewall has three coats posterior to the limbus, for clinical and practical purposes violation of only the most external structure is taken into consideration.
Closed Globe Injury- No full thickness injury ( No full- thickness wound of eyewall. )
Open Globe Injury- Full thickness injury ( Full- thickness wound of the eyewall. )
Closed- Globe subgroups:
Contusion- No full thickness injury (generally a blunt injury)
The injury is either due to direct energy delivery by the object (e. g., choroidal rupture) or
to the changes in the shape of the globe (e. g., angle recession)
Lamellar laceration- Partial thickness injury of the eye wall (generally a sharp injury)
Open-globe subgroups:
Rupture- Full-thickness injury of the eyewall caused by a blunt object
Since the eye is filled with incompressible liquid, the impact results in momentary increase of the IOP.
The eyewall yields at its weakest point (at the impact site or elsewhere;
example: an old cataract wound dehisces even though the impact occurred elsewhere);
the actual wound is produced by an inside- out mechanism
Laceration- Full-thickness injury of the eyewall caused by a sharp object
The wound occurs at the impact site by an outside- in mechanism
Laceration subgroups:
Penetrating injury- Single laceration of the eye wall; i.e. no exit wound, if more than one entrance wound then must be from a different agent
Penetrating injury Entrance wound. -If more than one wound is present, each must have been caused by a different agent
Intra-ocular foreign body- retained foreign objects causing entrance wounds
Technically a penetrating injury, but grouped separately because of different clinical implications
Perforating injury- two full thickness lacerations with an entrance and exit injury
Both wounds caused by the same agent
Source:AAO
*Some injuries remain difficult to classify. For instance, an intravitreal BB pellet is technically an IOFB injury. However, since this is a blunt object that requires a huge impact force if they enter, not just contuse, the eye, there is an element of rupture involved. In such situations, the ophthalmologist should either describe the injury as "mixed" (i. e., rupture with an IOFB) or select the most serious type of the mechanisms involved.
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