Complimentary imaging technologies in blunt ocular trauma.

We describe complimentary imaging technologies in traumatic chorioretinal injury. Color and fundus autofluorescence (FAF) images were obtained with a non-mydriatic retinal camera. Optical coherence tomography (OCT) helped obtain detailed images of retinal structure. Microperimetry was used to evaluate the visual function. A 40-year-old man sustained blunt ocular trauma with a stone. Color fundus image showed a large chorioretinal scar in the macula. Software filters allowed detailed illustration of extensive macular fibrosis. A 58-year-old man presented with blunt force trauma with a tennis ball. Color fundus imaging showed a crescentric area of macular choroidal rupture with fibrosis. FAF imaging delineated an area of hypofluorescence greater on fundus imaging. OCT showed chorioretinal atrophy in the macula. Microperimetry delineated an absolute scotoma with no response to maximal stimuli. Fundus imaging with digital filters and FAF illustrated the full extent of chorioretinal injury, while OCT and microperimetry corroborated the structure and function correlations.

Introduction

Based on the National Hospital Ambulatory Medical Care Survey, injuries represented 49% of 2.32 million projected emergency department visits for ocular problems.[1] Traumatic ocular injury can affect the choroid and retina in a variety of ways including choroidal rupture, retinal hemorrhages, edema, breaks, and detachment among others.[23] Examination of traumatic patients may prove difficult due to patient's potential loss of consciousness, lack of cooperation, and other injuries resulting in the clinician's inability to appreciate occult ocular injuries.[4] The addition of imaging, to a thorough clinical examination, may improve the detection of injury from blunt ocular trauma.

In the recent past, several studies relied of fundus autofluorescence (FAF) and optical coherence tomography (OCT) to characterize pathology observed in acute ocular injury and evaluate the utility of these imaging techniques during follow-up examinations.[56] In this report, we demonstrate the use of non-mydriatic fundus imaging with digital filters, FAF, OCT, and microperimetry in illustrating the full structural and functional sequelae of posterior segment manifestations of blunt ocular trauma secondary to projectile objects.

Case Report

Non-mydriatic color fundus images were obtained via a Canon CR-DGi camera with EOS-20 D 8.1 megapixel camera back (Tokyo, Japan) and saved on a laptop (Fujitsu, Kanagawa, Japan) with a high-resolution, wide-screen (1440 × 900 pixels; 32-bit color quality) preview. Detailed image analysis was performed using the Canon Eye-Q (Canon Medical Systems, Irvine, CA), software with a Digital Imaging and Communications in Medicine–compliant imaging, which allowed for separation of one image into three monochromatic channels (i.e., red, green, blue) to aid in image analysis. The blue (490 nm) filter, highlighting the nerve fiber layer, is used to evaluate eyes for glaucomatous change. The green (550 nm) filter, highlighting the neural retina, is used to evaluate eyes for diabetic and vascular changes. The red (610 nm) filter, highlighting the pigmented retina and the choroid, is used to evaluate eyes for changes associated with degenerative retina diseases. A fourth “emboss” digital filter allows for a topographical map evaluation of the posterior pole for graphic illustration of elevations or depressions.[7] FAF was assessed by a 15.1 megapixel Canon CX-1 non-mydriatic camera (530 nm/640 nm excitation/barrier filters; Tokyo, Japan). OCT (Optopol SD OCT; 3 μm resolution; Zawiercie, Poland) helped obtain detailed images of retinal structure. Frequency Doubling Technology (FDT) (Carl Zeiss Meditec Inc., Dublin, CA) and microperimetry (Nidek MP1 Microperimeter; Padova, Italy) was used to evaluate the visual function. Intraocular pressure (IOP) was measured with a Canon Tx-F full auto non-contact tonometer (Tokyo, Japan).

Case 1: Stone

A 40-year-old African American man presented with a past ocular history of blunt force trauma with a projectile object (stone) at age nine. No surgical intervention was recommended at that time. Vision deteriorated to counting fingers (CF) within a few weeks. At the screening examination, uncorrected visual acuity (VA) was 20/30 and CF, and IOP was 14 mm Hg and 22 mm Hg in the right and left eyes, respectively. FDT visual field testing showed a central scotoma.

The right eye fundus imaging was within the normal limits (not shown). Color fundus photo of the affected left eye showed an approximately two-disc diameter chorioretinal scar in the macular region [Figure 1a]. Image analysis was then performed using the digital red wavelength filter (610 nm) to better illustrate outer retinal pathology (including the retinal pigment epithelium [RPE] and choroidal findings) and showed extensive fibrosis and macular hypopigmentation [Figure 1b]. A topographical monochromatic filter created an “embossed” image of retinal elevations and depressions that highlighted topographic macular changes [Figure 1c]. Both images illustrated extensive fibrosis in the macula. The subject declined further evaluation with FAF and OCT or microperimetry for a more detailed assessment of the visual field.

Figure 1

Color fundus image (a) of the left eye shows well-circumscribed two-disc diameter area of chorioretinal atrophy with extensive macular fibrosis. Digital red filter. (b) [610 nm; delineates retinal pigment epithelium/choroid] demonstrates extensive fibrosis and macular hypopigmentation. Monochromatic “emboss” filter. (c) Highlights topographic macular changes

Case 2: Tennis ball

A 58-year-old Caucasian man presented with a past ocular history of blunt force trauma with a tennis ball at age 17. As in the first case, surgical intervention was not recommended at the time of injury and vision deteriorated to hand motions shortly thereafter. On examination, uncorrected VA in the affected eye was 20/800 and IOP was 13 mm Hg. The VA and IOP in the unaffected eye were within normal limits.

Color fundus imaging of the affected right eye [Figure 2a] showed a crescentric area of choroidal rupture with fibrosis and reactive hyperpigmentation involving the macula and extending to the vascular arcades with peripapillary atrophy. The digital red filter [Figure 2b] and monochromatic “emboss” filter [Figure 2c] showed good correlation with the extensive fibrosis noted on color imaging [Figure 2a]. FAF imaging [Figure 2d] delineated an area of hypofluorescence greater than that originally defined in Figure 2a-c. OCT [Figure 2e] showed chorioretinal atrophy in the macula and temporal retina (in contrast to the unaffected normal appearing nasal retina). Microperimetry testing of the central 10° field [Figure 3] showed an absolute scotoma with no response to maximal stimuli at 0 dB. The central scotoma corresponded to the involved retina.

Figure 2

Color fundus photo (a) of right eye shows extensive macular/perimacular fibrosis with reactive hyperpigmentation, peripapillary atrophy, choroidal rupture. Significant vessel attenuation can be appreciated. Digital red filter (b) and monochromatic emboss filter (c) delineate topographic changes corresponding to those in Figure 2a. Fundus autofluorescence (d) illustrates macular, perimacular, and peripapillary hypofluorescence of greater distribution than in a-c. Optical coherence tomography (e) confirms widespread retinal/choroidal atrophy in macular/temporal retina

Figure 3

Microperimetry of the central 10° shows an absolute scotoma corresponding to the involved retina with no response to maximal stimuli at 0 dB

Discussion

Digital filters, FAF, OCT and microperimetry appear to be complementary technologies that help physicians better identify the depth and extent of injury as well as the resulting functional impairment. These easy to perform, non-invasive, and rapid imaging modalities allow direct observation and correlation of structure and function. In both of our cases, ocular trauma with projectile objects had devastating visual consequences on the affected eyes with a resulting central scotoma as illustrated by FDT and microperimetry.

Few authors have reported their experience with the use of FAF and OCT for ocular trauma imaging.[689] Most recently, Lavinsky et al., evaluated six eyes of six consecutive patients within 30 days of sustaining blunt ocular trauma secondary to rock (n = 3), piece of wood (n = 1), and motor vehicle accident (n = 2).[5] In this study, three patients presented with RPE epitheliopathy and three with subretinal hemorrhage with choroidal rupture. These manifestations appeared as hypofluorescence with hyperfluorescent granular lesions and hypofluorescence with a hyperfluorescent rim on FAF imaging, respectively. In addition, in patients with choroidal rupture, OCT showed disorganization of the choriocapillaris and the RPE. The authors concluded that FAF and OCT was helpful in the initial and subsequent examination of patients with blunt ocular trauma. Similar to the observations by Lavinsky et al.,[5] we observed an improved ability to delineate the extent of chorioretinal pathology with FAF compared to color fundus imaging. In addition, we were able to correlate areas of hypofluorescence to reduced retinal sensitivity on microperimetry.

Since blunt ocular trauma can cause significant disruption to the RPE, choroid, and the choriocapillaris, it is not surprising that FAF and OCT were able to clearly delineate damage not observed on clinical examination or color imaging. The use of digital filters in early detection and timely treatment or retreatment in patients with diabetic retinopathy and age-related macular degeneration has been studied.[10] We believe that a similar paradigm may be successfully applied to patients presenting with blunt ocular trauma. In addition, the combination of digital filters and FAF may be particularly helpful in patients with medical comorbidities who may have contraindications to fluorescein angiography. Based on the aforementioned studies and our observations, we believe that the utility of these imaging technologies in the examination of patients with blunt ocular trauma warrants further investigation.