How Does Subretinal Hemorrhage Damage the Retina

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A thick subretinal hemorrhage situated under the fovea occasionally has a natural course that leads to severely decreased visual function even in those without choroidal neovascularization. Animal experiments have shown that the photoreceptors can be damaged by the toxic effects of the iron released by red blood cells as well as by mechanical blockage by the hemorrhage, which hinders metabolic exchange between the photoreceptors and the RPE cells [1].

Subretinal macular hemorrhages can be successfully removed by vitrectomy using tissue plasminogen activator [2], leading to an improvement in the postoperative visual acuity of patients whose vision was good before the hemorrhage [3] (Fig. 4.31).

Changes in the focal macular ERGs elicited by a 10° spot in five patients who had a sub-macular hemorrhage removed by vitrectomy using tissue plasminogen activator are shown in Fig. 4.32. The submacular hemorrhage was caused by rupture of a macroaneurysm in three of the eyes, AMD in one of the eyes, and an unknown reason in the fifth eye. The duration of the subretinal hemorrhage ranged from 3 to 14 days. All of the patients had extremely poor visual acuity (from hand motion to 0.05) before surgery, and the visual acuity improved to 0.1-0.7 after surgery.

Three points can be made based on these results. First, focal macular ERGs were unde-tectable in all of these patients before surgery regardless of the duration of the submacular hemorrhage. This is definitely different from the results from patients with idiopathic central serous chorioretinopathy, where serous fluid, not blood, accumulates between the photore-ceptors and the RPE. Patients with central serous chorioretinopathy usually have much better visual acuity with good-amplitude focal macular ERGs (see Section 4.1). This difference indicates that blood can alter the function of the photoreceptors much more so than can serous fluid.

Second, the decline of photoreceptor function is partially reversible when blood is removed from the subretinal space even after 14 days, as shown by the recovery of the focal macular ERG in case 5. However, it is more likely that the earlier the blood is removed the better is the recovery. The third point is that there is little if any toxic effect of recombinant tissue plasminogen activator injected at clinically useful doses.

O Fig. 4.31. Top: Preoperative fundus photograph with a 10° spot superimposed on the fovea. The image was obtained while recording the macular ERG in a patient with submacular hemorrhage.Bottom: Postoperative photograph. The retinal blood is almost completely removed. (From Terasaki et al. [3], with permission)

Fig. 4.32. Focal macular ERGs recorded from five patients with subretinal macular hemorrhage. The stimulus spot was 10° in diameter. The fellow eye of case 5 shows no response because of macular degeneration of unknown cause. After surgical drainage of the subretinal hemorrhage using human plasminogen activator, there is partial recovery of the ERG in all patients. (From Terasaki et al. [3], with permission)

Fig. 4.32. Focal macular ERGs recorded from five patients with subretinal macular hemorrhage. The stimulus spot was 10° in diameter. The fellow eye of case 5 shows no response because of macular degeneration of unknown cause. After surgical drainage of the subretinal hemorrhage using human plasminogen activator, there is partial recovery of the ERG in all patients. (From Terasaki et al. [3], with permission)

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