Purpose:
The macular sub-ILM space is an area of predilection for hemorrhage to accumulate. Its management ranges from observation to laser membranotomy and surgery. In the presence of clear optical media, ocular coherence tomography (OCT) can been used to determine its exact location [Fig.1].
Methods:
We present a consecutive case series of ILM specimens that were excised for sub-ILM hemorrhage. The specimens were studied by routine histopathology and by immunohistochemistry. In the latter, cytokeratin 7 was used to identify retinal pigment epithelium (RPE) cells, glial fibrillary acidic protein (GFAP) was used to mark glial cells and CD68pg to detect macrophages. Prussian Blue staining was used to reveal haemosiderin.
Results:
The series consisted of 9 ILM specimens from 8 patients with sub ILM hemorrhage. The etiologies were: 4 Terson’s Syndrome, 2 ruptured macroaneurysms and 3 cases of Valsalva retinopathy. Seven cases were operated after 15.2 weeks (±8.7)(range=6-26 weeks) due to late presentation and 2 patients were operated after 2.5 weeks(±0.7)(range=2-3 weeks). Cellular proliferations were found in an unusual location: on the retinal surface of the excised ILM in 7 of the 9 specimens. The cellular components included transdifferentiated RPE cells, glial cells and macrophages mimicking a PVR-type response. Prussian blue staining showed that the pigment was a mix of melanin and haemosiderin. The two specimens without cellular proliferation were from the patients with the shortest time from clinical onset to surgery.
Conclusions:
Our case series suggests that focal cellular proliferation, similar to that seen in PVR epiretinal membranes, commonly occurs within the neuroretina after hemorrhage, specifically in the sub-ILM location. Such proliferation might prevent complete visual recovery after reabsorption of the retinal hemorrhage and justify early surgical intervention instead of routine observation or laser membranotomy.
Keywords: proliferative vitreoretinopathy • immunohistochemistry • retinal pigment epithelium