Posterior Segment
Trauma
Hajir Dadgostar, MD, PhD, Alexandre A.C.M.Ventura, MD,
Brandy C. Hayden, BS*
KEYWORDS
Vitreous hemorrhage Retinal detachment
Choroidal detachment Lens dislocation
Intraocular foreign body Endophthalmitis
Ocular trauma is a major cause of vision loss, particularly among younger patient populations. Vitreoretinal involvement is present in nearly 50% of all severe eye injuries secondary to blunt or penetrating trauma.1 Clinical examination of the posterior segment can, however, be limited in such cases by factors related to the injury. Coexisting anterior segment injury can result in hyphema or corneal edema and opacification. Traumatic posterior segment pathologies, such as vitreous hemorrhage or vitritis, also can limit the diagnostic information obtained from clinical examination. In such cases, B-scan ocular ultrasonography has been shown to yield valuable diagnostic and prognostic information to define the nature of the pathology and guide management.2,3 In a review of 154 eyes with various posterior segment disorders for which ultrasound was ordered at one institution, it was reported that ultrasonography data made an impact on disease diagnosis or management in 83% of cases and were ‘‘pivotal’’ in 14% of cases.4 In this article, we describe the clinical and ultrasonographic features of several commonly encountered trauma-associated diagnoses that involve the posterior segment in which ocular ultrasound can provide useful information.
RHEGMATOGENOUS RETINAL DETACHMENT
Trauma is the most common cause of retinal detachment in children and may play a role in approximately 10% of retinal detachments overall.1,5 Retinal detachment after blunt trauma may develop as a result of retinal dialysis, flap tears,
or giant retinal tears through rapid compressiondecompression forces that result in transient anteroposterior shortening and equatorial elongation of the globe. It is estimated that 70% of hemorrhagic posterior vitreous detachments may have an associated retinal tear,6 and this association is likely even greater in the specific setting of trauma. Peripheral tears also can occur as a result of trauma-induced vitreous detachment.
Although indirect ophthalmoscopy remains the technique of choice for diagnosing a retinal tear or detachment in this setting, ultrasound can be of value when the view of the posterior segment is obscured by dense vitreous hemorrhage. A small, peripheral retinal tear appears as a focal, highly reflective flap on B-scan (Fig. 1). The posterior vitreous is usually thickened and partially detached but remains adherent to the retina at the location of the tear. In addition to the dense vitreous hemorrhage, this adhesion sometimes can make the diagnosis of a peripheral retinal tear difficult and can lead to false-negative results. In a review of 106 eyes undergoing ultrasonography for dense vitreous hemorrhage, only 44% of retinal tears were diagnosed accurately.7 To maximize diagnostic sensitivity, examination of a suspicious area at a low gain and focally guided ocular movements to access flap mobility are essential.
Because many cases involve younger patients with formed vitreous, the progression of a tear or dialysis to a detachment may take weeks to months;8 however, giant retinal tears have a much higher chance of progressing rapidly to retinal detachment.9 Giant retinal tears present
Diagnostic Imaging, Cole Eye Institute (i-10), Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA
* Corresponding author.
E-mail address: haydenb@ccf.org (B.C. Hayden).
Ultrasound Clin 3 (2008) 267–272 doi:10.1016/j.cult.2008.04.006
1556-858X/08/$ – see front matter ª 2008 Elsevier Inc. All rights reserved.
ultrasound.theclinics.com
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Fig. 1. Peripheral retinal tear. Longitudinal B-scan at a low gain displays small, highly reflective flap (arrow).
on ultrasound as highly reflective, discontinuous, rope-like membranes within the vitreous space (Fig. 2). In the presence of dense hemorrhage, standardized diagnostic A-scan is an essential tool in the differentiation of a discontinuous, thickened posterior vitreous detachment from a giant retinal tear (Fig. 3).
Penetrating ocular injury that tears the retina directly typically does not result in immediate rhegmatogenous detachment. In these cases, a delayed combined tractional and rhegmatogenous detachment often results from intraocular fibrovascular proliferation that originates from the site of injury (Fig. 4).10 As demonstrated in animal models, this progressive proliferative vitreoretinopathy ultimately can lead to total retinal detachment, hypotony, and phthisis, if untreated.11,12
The treatment for traumatic rhegmatogenous retinal detachments typically involves scleral buckling and vitrectomy techniques used alone or in combination. Although the presence of vitreous hemorrhage, proliferative vitreoretinopathy, or
Fig. 3. Diagnostic A-scan directed perpendicular to the retinal tear shows a 100% spike at tissue sensitivity.
other complicating factors (eg, intraocular foreign body [IOFB]) often necessitates a combination of vitrectomy and scleral buckling, cases with a good view of the posterior segment and a welldefined tear or dialysis can be treated with scleral buckling alone.1 When a retinal tear is diagnosed in the presence of dense vitreous hemorrhage, a vitrectomy is usually required to prevent progression to retinal detachment. Ultrasound-guided external cryopexy in this setting also has been reported as a less invasive alternative approach, however.13
HEMORRHAGIC CHOROIDAL DETACHMENT
Although most commonly encountered as a postoperative complication, particularly after cataract surgery, glaucoma filtration surgery, or scleral buckling procedures, choroidal detachments are also known to occur in association with openglobe injury.14 Posterior segment ultrasound can be useful for differentiating retinal and choroidal detachments, measuring the extent of choroidal
Fig. 2. Giant retinal tear. Transverse B-scan shows dis- |
Fig. 4. Combined tractional and rhegmatogenous ret- |
continous, folded, hyperechoic retina. |
inal detachment at the site of globe penetration. |
detachments, and distinguishing hemorrhagic from exudative choroidal detachments (Figs. 5–7). Typically, shallow to moderate choroidal detachments can be followed with serial examination and ultrasound as needed, with prompt attention to the repair of the globe and any associated ocular injuries. Extensive, appositional (or ‘‘kissing’’) choroidal detachments, on the other hand, often require surgical drainage, typically after a 1- to 2-week delay to allow liquefaction of the blood clot (Fig. 8).15 Serial ultrasound can be used to aid in the timing of surgery in these cases because clot liquefaction sometimes may become apparent on dynamic ultrasonography. Surgical management often involves transscleral drainage of the blood with or without concurrent vitrectomy.
LENS DISLOCATION
Blunt trauma can lead to the subluxation or dislocation of the crystalline lens or intraocular lens implants through the disruption of zonular fibers. Lens dislocation or subluxation has been reported from several sources of blunt trauma, including seizure-related injury,16 airbag deployment,17 paint-ball injuries,18,19 bottle corks,20 and elastic cord–related injuries.21–23 Subluxed lenses often can be identified with the slit-lamp, and subtle cases can be distinguished by looking for associated signs, such as iridodonesis and phacodonesis. Complete dislocation of an intraocular lens or crystalline lens can be identified in the posterior segment through indirect ophthalmoscopy, although dislocation into the anterior chamber or even the subconjunctival space also can occur.24–26
In cases in which other trauma-associated pathologies, such as corneal opacification, hyphema, and vitreous hemorrhage, preclude posterior segment examination, dynamic
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Fig. 6. Hemorrhagic choroidal detachment. Transverse B-scan demonstrates scalloped appearance of choroid with dense opacities in the suprachoroidal space.
ultrasonography can help to determine the position of the dislocated lens. On B-scan, a posteriorly dislocated crystalline lens appears as an ovalshaped, highly reflective mass that can be misdiagnosed as an intraocular tumor without careful attention to internal reflectivity and mobility (Fig. 9). A traumatically displaced intraocular lens appears as a highly reflective linear body with marked reverberations along the echoic plane and two focal areas of reverberations corresponding to the intraocular lens haptics (Fig. 10). Management options for crystalline lens injury range from observation in cases of mild subluxation without significant traumatic cataract to lens removal using vitrectomy techniques in cases of complete posterior dislocation.27
INTRAOCULAR FOREIGN BODY
IOFBs are encountered in 18% to 41% of cases that involve open globe trauma.28 Young men are
Fig. 5. Serous choroidal detachment. Transverse B-scan demonstrates scalloped appearance of choroid with absence of opacities in the suprachoroidal space.
Fig. 7. Diagnostic A-scan directed perpendicular to the elevated membrane shows a double spike at tissue sensitivity indicative of a choroidal detachment.
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Fig. 8. Appositional (kissing) choroidal detachments. Longitudinal B-scan shows bullous choroidal detachments with central touch with dense opacities in the suprachoroidal space.
the most frequently affected, and hammering is the most frequent predisposing activity, accounting for 60% to 80% of cases.29–31 Although pain and vision loss are common presenting symptoms, both of these symptoms may be absent.32,33 In any open globe injury, the clinician must maintain a high index of suspicion for the presence of IOFB. In one study, up to 56% of all trauma-related legal claims were related to missed IOFBs.34
In addition to clinical examination at the slitlamp and indirect ophthalmoscopy, various imaging modalities are valuable for the identification and localization of IOFB. Although plain radiographs have been used in the past, modern CT scans have a much higher sensitivity.35,36 MR imaging is contraindicated when metallic IOFB is suspected. Adjunctive use of ultrasound by a skilled technician can increase the likelihood of detecting IOFB. Using a porcine eye model, one
Fig.10. Posteriorly dislocated intraocular lens implant. Oblique transverse B-scan shows a highly reflective echo source causing marked shadowing of the posterior orbit.
study demonstrated a 93% IOFB detection rate with ultrasound.37 In another experimental model using metallic IOFBs of different sizes, sensitivity, specificity, positive predictive value, and negative predictive value of detection by ultrasound were 87.5%, 95.8%, 96.5%, and 85.2%, respectively.38
Diagnostic ultrasound is valuable in determining the precise location and orientation of small IOFBs and distinguishing between objects composed of different materials. Extremely thin IOFBs (< 100 mm), such as a metallic wire or a splinter of wood, can be differentiated, localized, and measured with B-scan (Fig. 11). Metallic IOFBs are echo dense—even at low gain settings—and often produce shadowing of intraocular structures and the orbit. Organic IOFBs produce various findings on ultrasound depending on the shape and structure of the material. These foreign bodies are usually echo dense at low gains. Intraocular
Fig. 9. Posteriorly dislocated normal crystalline lens. Longitudinal B-scan demonstrates smooth, oval mass with foci of high reflectivity.
Fig. 11. Intraocular metallic wire foreign body. Transverse B-scan shows hyperechoic foreign body with mild reduplication echoes and shadowing.