Unraveling the perplexities of choroidal rupture

Choroidal rupture (CR) was first described by von Graefe in 1854 in patients with blunt or penetrating ocular trauma. As the name suggests, a CR is a break in the choroid, Bruch’s membrane, and retinal pigment epithelium (RPE). About 5–10% of cases of blunt ocular trauma result in CR.[1] CR may be direct (coup injury) or indirect (countercoup injury). A direct CR occurs anteriorly at the site of impact, generally parallel to the ora serrata and peripheral retina, whereas an indirect CR occurs away from the site of impact, more posteriorly and concentric to the optic disk in a crescent shape manner. The majority (~80%) of choroidal ruptures are indirect.[1] The exact mechanism behind a CR remains unidentified but is believed to be related to mechanical forces generated during trauma. Anterior–posterior deformation of the globe expands the eye equatorially resulting in a shear force that radiates concentrically from the nerve. The retina and sclera are relatively more elastic and therefore can withstand resistance to rupture. The Bruch’s membrane on the other hand is less elastic and breakdowns more easily.[1-3] Patients with pseudoxanthoma elasticum are more prone to CR following even minor trauma due to the fragility of Bruch’s membrane.[1] Histopathologic analysis of CR reveals early hemorrhage which may be choroidal, subretinal, and even vitreous hemorrhage.[1,4] The overlying retina may show early thinning or atrophy. The fibroblastic activity begins usually 4 days after injury and continues up to 2 weeks. This is followed by extensive scarring. Hyperplasia of the retinal pigment epithelium is also a common finding at 3–4 weeks after CR.[4] In a study done on 111 cases of traumatic choroidal rupture, it was found that ruptures occurred in the macula in approximately 68% of cases, with 37% of cases being foveal and 31% being extrafoveal.[5] One of the most common risk factors identified for the development of choroidal neovascularization (CNV) after ocular trauma is CR.[6] Approximately 5–10% of eyes with CR develop CNV which may result in delayed visual loss.[3,7] Rupture location and poor presenting visual acuity are independently associated with visual outcomes.[5] Ruptures located closer to the fovea are more likely to develop neovascularization than ruptures located peripherally (1500 μm from the foveal avascular zone).[8] Also, longer ruptures (4000 μm), independent of location, are susceptible to the development of neovascularization.[8] A late hemorrhagic detachment of the pigment epithelium secondary to sub-RPE neovascularization has also been described by some in trauma associated with a baseball cap.[9,10] Fundus autofluorescence typically shows hypo-autofluorescence within the rupture due to loss of the RPE and also due to subretinal hemorrhage along with hyper autofluorescence of the rupture rim, due to pigment epithelium hyperplasia at the margins of the rupture, which has been well documented clinically and histologically.[4,11,12] Two distinct patterns of indirect choroidal rupture are seen in the spectral domain OCT. Type 1 shows forward protrusion of the RPE/choriocapillaris layer with an acutely angled pyramid associated with either a small loss of continuity of the RPE layer or an elevated RPE/choriocapillaris projection accompanied by a significant quantity of subretinal hemorrhage. Type 2 shows a larger area of disruption of the RPE/choriocapillaris layer, photoreceptor ellipsoid zone, and external limiting membrane, with a posteriorly directed concave contour depression and downward sliding of tissues into the defect.[13] OCT-A can be used for early diagnosis of CNV with good sensitivity and specificity in traumatic CR.[14] Prior to the advent of intravitreal anti-vascular growth factor (VEGF) therapy, CNV associated with CR was managed either by observation, laser photocoagulation, photodynamic therapy, or sub-macular surgery. Several case reports have reported anti-VEGF injections for CNV resulting from choroidal ruptures.[15-17] Although CNV associated with choroidal rupture tends to regress spontaneously, studies have proved that visual outcomes are worse for those patients who are not treated with any anti-VEGF therapy.