Surgical Management and Rehabilitation of Anterior Segment Trauma

Slit Lamp Examination

A portable slit lamp is necessary for children and patients who are unconscious or in cervical collars. Examination begins with inspection of the lids and conjunctiva; the extent of subconjunctival hemorrhage and the presence of conjunctival chemosis is recorded.

Corneal lacerations, abrasions, or foreign bodies raise the suspicion of possible globe perforation. If the globe is thought to be intact, the upper lid is everted to remove any retained or embedded foreign material in the upper fornix. The position and depth of corneal foreign bodies, as well as the depth and extent of a laceration, is documented ( Fig. 149.2 ). Seidel testing may be necessary to determine whether a full-thickness corneal laceration exists. If no leakage of aqueous is present, gentle pressure applied to the globe will delineate any self-sealing perforations. If leakage of aqueous is present, the remainder of the examination proceeds with minimal trauma ( Fig. 149.3 ), and no topical medications are placed in the eye for fear of entry into the anterior chamber. The anterior chamber may be abnormally shallow in penetrating or perforating injuries. Conversely, a deep chamber may result from acute angle recession, lens dislocation, or posterior globe rupture. The presence of blood, lens fragments, vitreous, or foreign bodies is documented. Foreign bodies that penetrate the anterior chamber but fail to embed in the iris or lens may fall to the angle at the 6 o’clock position and are extremely difficult to see on routine slit lamp examination. Application of a four-mirror lens will help identify intracameral foreign bodies but is postponed in an open globe injury ( Fig. 149.4 ).

Inspection of the iris includes the overall contour and geometry by both direct and retroillumination to detect small holes or perforations, which are caused by intraocular foreign bodies. These iris defects help estimate the location of foreign bodies. Peaking of the pupil may indicate vitreous prolapse into the anterior chamber or iris prolapse through the wound ( Fig. 149.5 ). A hyphema may obscure the iris details or a foreign body. Sphincter tears and areas of iridodialysis are noted. Iridodonesis indicates likely dislocation of the lens with associated zonular rupture. Capsular perforation or rupture causes regional opacification of the crystalline lens. Free-floating lens fragments or flocculent material in the anterior chamber indicate obvious lens rupture. The presence or absence and location of an intraocular lens (IOL) implant are noted. In the presence of an obvious corneal laceration or ruptured globe, measurement of intraocular pressure is inappropriate. When globe rupture is not obvious, low intraocular pressure may suggest occult rupture; normal or elevated intraocular pressure does not exclude this condition. Low intraocular pressure may also occur with a cyclodialysis cleft. The least traumatic method of measuring the intraocular pressure is recommended.

Examination of the vitreous and retina may be performed initially at the slit lamp unless large quantities of vitreous hemorrhage preclude observation of the retina. The presence of red blood cells and pigment in the vitreous may indicate retinal tears. Every effort should be made to view the retina during initial examination, as the initial examiner may be the only one to see the posterior pole in the face of increasing ocular hemorrhage or opacification of the lens. Retinal detachment, choroidal detachment, or choroidal ruptures may all be seen in blunt or penetrating trauma.

Imaging

Plain film radiography offers advantages in depicting the shape and number of metallic foreign bodies or localizing orbital wall fractures. In the case of a suspected metallic foreign body, a negative plain film may make more expensive tests unnecessary. ^, Computed tomography (CT) scanning in the traumatized eye and orbit detects both metallic and nonmetallic radio dense foreign bodies 1 mm in size using overlapping 1.5 mm sections. Bone-free projections are used to detect small radiolucent foreign bodies in the anterior segment and help diagnose orbital fractures and optic nerve avulsions. Wooden foreign bodies can be difficult to detect on CT because they appear hypoattenuating, similar to air. CT scanning may also assist in the diagnosis of occult globe rupture based upon subtle asymmetry in AC depth. Magnetic resonance imaging (MRI) detects a wide variety of vegetable, plastic, glass, and radiolucent foreign bodies in the eye, orbit, and adnexa. Surface coils allow higher resolution of orbital imaging in cases of ocular trauma ( Fig. 149.6 ). The potential for tissue damage from movement of a ferromagnetic foreign body precludes the use of MRI as a screening technique.

If there is no view of the posterior pole in an intact globe after blunt trauma, B-scan ultrasonography is used to detect a vitreous hemorrhage, retinal detachment, choroidal detachment, or intralenticular foreign body. Glass and metallic foreign bodies are very reflective and appear as bright areas on B-scan. Standard B-scan ultrasonography may determine whether a small foreign body is within or immediately outside the globe. Ultrasound biomicroscopy (UBM) and anterior segment OCT (AS-OCT) provides angle visualization when gonioscopy is not possible and can aid in the localization and removal of small intraocular foreign bodies, particularly in the angle, ciliary sulcus, and ciliary body. Additionally, UBM and AS-OCT can be used to evaluate for posterior capsule integrity and surgical planning for traumatic cataracts. Although UBM is more accurate, AS-OCT is a noncontact imaging modality and is particularly valuable in open globe injuries. Ocular CT can aid in the localization and identification of anterior segment foreign bodies and assist in the visualization of otherwise difficult areas to visualize, such as the sulcus, anterior chamber angle, and the ciliary body.