"Retrobulbar haemorrhage is the presence of a post-septal orbital haematoma and is usually due to craniofacial trauma, causing an extraconal haematoma. It may cause orbital compartment syndrome, which is an ophthalmologic emergency."
Line 1:66·Only use medical adjectival hyphens where the letters at the end and start of the compound word are the same, e.g. post-transplant. In this case, don't use the hyphen: 'post-septal'.