Henle fibre layer haemorrhage: clinical features and pathogenesis.

BACKGROUND: To describe the clinical presentation and characteristic imaging features of deep retinal haemorrhages primarily located in the Henle fibre layer (HFL) of the macula. The spectrum of aetiologies and a comprehensive theory of pathogenesis are presented.
METHODS: This is a retrospective, multicentre case series evaluating eyes with retinal haemorrhage in HFL. Clinical features, underlying aetiology, systemic and ocular risk factors, visual acuity, and multimodal imaging including fundus photography and cross-sectional and en face optical coherence tomography (OCT) are presented.
RESULTS: Retinal haemorrhages localised to HFL in 33 eyes from 23 patients were secondary to acute blunt trauma to the head (n=2), eye (n=1) and trunk (n=1), ruptured intracranial aneurysm (Terson's syndrome, n=3), general anaesthesia (n=1), epidural anaesthesia (n=1), hypertension with anaemia (n=1), decompression retinopathy (n=1), postvitrectomy with intraocular gas (n=1), retinal vein occlusion (n=7), myopic degeneration (n=2), macular telangiectasia type 2 (n=1), and polypoidal choroidal vasculopathy (n=1). Defining clinical features included deep retinal haemorrhage with feathery margin and petaloid pattern radiating from the fovea. OCT demonstrated characteristic hyper-reflectivity from the haemorrhage delineated by obliquely oriented fibres in the Henle layer. Spontaneous resolution of HFL haemorrhage occurred after 3 months in 15 patients with follow-up.
CONCLUSION: The characteristic petaloid-shaped, deep intraretinal haemorrhage with a feathery margin localised to HFL is associated with various disorders. The terminology 'Henle fiber layer hemorrhage (HH)' is proposed to describe the clinical and OCT findings, which may result from abnormal retinal venous pressure from systemic or local retinovascular disorders affecting the deep capillary plexus or from choroidal vascular abnormalities. © Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.