Retinal Hemorrhage Patterns: Layers, Shapes & Causes

Retinal hemorrhage takes different shapes depending on the layer where the blood collects, and the shape gives a first clue to the cause.

A flame-shaped hemorrhage in the nerve fiber layer, a round dot in the inner nuclear layer, and a boat-shaped collection in front of the retina reflect different anatomy and different diseases.

Learning to name the layer before naming the disease makes fundus examination more systematic and helps with the next test to order.

Why the Shape of a Retinal Hemorrhage Matters

Blood spreads along the planes of least resistance.

In the nerve fiber layer the axons run parallel to the surface, so blood forms linear or flame-shaped streaks that follow the fibers.

In the deeper layers, the vertical orientation of the cells and the compact structure restrict spread, and blood forms round or blot-like collections.

Blood in front of the retina collects in the potential spaces beneath the internal limiting membrane or the posterior hyaloid.

Blood beneath the retina or the RPE is dark and lies beneath the retinal vessels.

The location gives a clue about the source vessel.

Types of Retinal Hemorrhage

Flame-Shaped (Nerve Fiber Layer)

Feathery, red streaks that follow the arcuate nerve fiber pattern, often near the disc
Arise from superficial radial peripapillary capillaries
Seen in hypertensive retinopathy, retinal vein occlusion, papilledema, and disc swelling from other causes (see hypertensive retinopathy)
Seen at the edge of a swollen disc in papilledema, and in vein occlusions of the affected sector

Dot and Blot (Deep Retinal)

Round, sharply demarcated dots and blots in the inner nuclear and outer plexiform layers
Arise from the deep capillary plexus and microaneurysms
Typical of diabetic retinopathy, and also seen in vein occlusion, ocular ischemic syndrome, and hypertension
Blot hemorrhages are larger, and clusters suggest ischemia

Preretinal or Subhyaloid

Boat-shaped or crescent hemorrhage with a flat upper border, sometimes with a fluid level
Collects between the ILM and the posterior hyaloid
Seen in proliferative diabetic retinopathy, Valsalva retinopathy, Terson syndrome, and trauma (see Valsalva retinopathy and Terson syndrome)

Sub-ILM

Smooth, dome-shaped collection that does not layer
Seen in Valsalva retinopathy and trauma

Subretinal

Dark red or gray-green, deeper than the retinal vessels, with a smooth margin
Seen in neovascular AMD, retinal macroaneurysm, trauma, and choroidal tumors (see macroaneurysm)

Sub-RPE

Dark, well-demarcated dome, sometimes brown-black
Seen in polypoidal choroidal vasculopathy and choroidal neovascularization
Can mimic choroidal melanoma

Roth Spots

Hemorrhages with a white or pale center
Historically linked to bacterial endocarditis, but also seen in leukemia, anemia, diabetes, hypoxia, and connective tissue disease (see Roth spots)
The white center may be a fibrin-platelet plug or a cluster of inflammatory or neoplastic cells

Vitreous Hemorrhage

Blood in the vitreous gives haze or a dense obscuration of the fundus (see vitreous hemorrhage).

Distribution Patterns

The distribution across the fundus helps as much as the layer.

Diffuse in all quadrants: central retinal vein occlusion, hyperviscosity, severe anemia or thrombocytopenia (see central retinal vein occlusion)
Sectoral: branch retinal vein occlusion, following the territory of the affected vein (see branch retinal vein occlusion)
Peripapillary: papilledema, disc swelling, disc hemorrhage in glaucoma
Macular: Valsalva retinopathy, macroaneurysm, trauma, neovascular AMD
Midperipheral, mostly deep: ocular ischemic syndrome and diabetic retinopathy
Multiple layers, extending to the periphery: abusive head trauma, a pattern that needs careful documentation (see shaken baby syndrome)
Bilateral and symmetric: systemic disease such as hypertension, blood disorders, or diabetes

Systemic Causes to Consider

Diabetes and hypertension
Blood disorders: anemia, thrombocytopenia, leukemia, hyperviscosity
Anticoagulant and antiplatelet therapy
Infective endocarditis and sepsis
Vasculitis and connective tissue disease
Increased venous pressure from straining, vomiting, or chest compression (Purtscher-like patterns are described in Purtscher retinopathy)
High-altitude exposure
Head and chest trauma
Neonatal hemorrhages after vaginal delivery, which are common and usually resolve within weeks

A blood pressure check, glucose, and complete blood count are the minimum initial tests.

Investigations

Dilated fundus examination with scleral depression, since peripheral findings help distinguish causes
Fundus photographs, ideally widefield, for documentation
OCT to place the hemorrhage in a layer, and to identify macular edema
Fluorescein angiography to show the source of bleeding, leakage, and nonperfusion, recognizing that blood blocks fluorescence
B-scan ultrasonography when the view is obscured
Systemic tests directed by the pattern

Mimics and Pitfalls

Several findings are mistaken for retinal hemorrhage.

Pigmented lesions such as a choroidal nevus, CHRPE, or a melanocytoma, which do not change with time and lack the feathery margins of blood
Vascular tufts and macroaneurysms, which are the source of the bleed and may be hidden by it
Retinal neovascularization, whose fronds may be surrounded by hemorrhage
Sub-RPE blood over a polypoidal lesion, which may look like a melanoma

Dates matter as well.

Fresh blood is bright red, and it turns yellow-brown as it ages, so a change in color over days to weeks supports hemorrhage.

A lesion that stays dark and unchanged for months should be reassessed for a pigmented tumor.

Management

Management addresses the cause.

Hypertension and diabetes require systemic control
Retinal vein occlusion is treated for macular edema and neovascularization
Bleeding disorders and drug effects need medical management
Preretinal hemorrhage may be observed or treated with laser hyaloidotomy or vitrectomy if it blocks central vision
Trauma needs a full examination for other injuries
Suspected abusive head trauma needs urgent multidisciplinary evaluation according to local child protection protocols

Most hemorrhages resolve over weeks, and the visual outcome depends on the damage to the underlying retina.

References

Schachat AP, Sadda SR, Hinton DR, Wilkinson CP, Wiedemann P, eds. Ryan’s Retina. 6th ed. Philadelphia: Elsevier; 2018.
Salmon JF. Kanski’s Clinical Ophthalmology: A Systematic Approach. 9th ed. Philadelphia: Elsevier; 2020.
Levin AV, Christian CW; Committee on Child Abuse and Neglect, Section on Ophthalmology. The eye examination in the evaluation of child abuse. Pediatrics. 2010;126:376-380.
Emerson MV, Pieramici DJ, Stoessel KM, Berreen JP, Gariano RF. Incidence and rate of disappearance of retinal hemorrhage in newborns. Ophthalmology. 2001;108:36-39.
Wong TY, Mitchell P. Hypertensive retinopathy. N Engl J Med. 2004;351:2310-2317.

Retinal Hemorrhage Patterns: What the Layer, Shape and Color Tell You