A boat-shaped hemorrhage usually lies in which location?

Beneath the posterior hyaloid or ILM Boat-shaped hemorrhage is a preretinal bleed that usually lies beneath the posterior hyaloid or the internal limiting membrane, so the sign localizes the blood.

Between the RPE and Bruch membrane

Within the suprachoroidal space

Why does a boat-shaped preretinal hemorrhage have a flat, horizontal upper border?

Red cells settle by gravity below the plasma Blood in a confined preretinal space settles as gravity pulls red cells down while plasma stays above, giving a horizontal interface in an upright patient.

The hyaloid is attached along a horizontal line

Nerve fiber bundles limit upward spread

Fibrin contracts along the horizontal raphe

Which feature suggests a sub-ILM rather than subhyaloid location for a boat-shaped hemorrhage?

A taut dome with a glistening surface Sub-ILM blood often forms a taut, glistening dome, while subhyaloid blood may shift with posture; a sub-ILM collection may need ILM peeling.

Diffuse blurring of the fundus view

Blood lying beneath the retinal vessels

What distinguishes subretinal blood from a boat-shaped preretinal hemorrhage?

It lies beneath the retinal vessels Subretinal blood lies beneath the retinal vessels and often looks darker, whereas a preretinal boat-shaped bleed hides the vessels beneath it.

It follows the nerve fiber layer pattern

It blurs the whole fundus view diffusely

It forms a horizontal fluid level

A patient with a boat-shaped hemorrhage has severe headache and confusion. Which diagnosis must be considered?

Terson syndrome from subarachnoid hemorrhage Terson syndrome may be the first ocular clue to subarachnoid hemorrhage, so severe headache, confusion or reduced consciousness needs urgent neurological assessment.

Which boat-shaped hemorrhage is most suited to observation?

A small bleed that spares the fovea Observation suits small bleeds that spare the fovea, though reabsorption can take weeks or months and follow-up should check for new neovascularization.

A dense pool covering the fovea

A bleed with fibrovascular traction

A bleed after failed laser drainage

Nd:YAG hyaloidotomy works best for which type of boat-shaped hemorrhage?

An old, clotted subretinal bleed

Which complication is a recognized risk of Nd:YAG hyaloidotomy for premacular hemorrhage?

Macular hole Risks of Nd:YAG hyaloidotomy include macular hole, retinal detachment and epiretinal membrane.

Corneal endothelial decompensation

After a boat-shaped hemorrhage from proliferative diabetic retinopathy is drained, what further treatment is still needed?

Panretinal photocoagulation or anti-VEGF therapy Drainage clears the visual axis but leaves the bleeding source untreated, so proliferative disease still needs panretinal photocoagulation or anti-VEGF therapy.

No further treatment once vision clears

Topical corticosteroids for one month

Repeat Nd:YAG laser every three months

Why should a patient with a boat-shaped hemorrhage be re-examined within one to two weeks?

The bleed may enlarge or rupture into the vitreous Early review within one to two weeks is advised because the bleed may enlarge or break into the vitreous; its size is then followed with photographs or OCT.

To start anti-VEGF before the blood clears

To measure intraocular pressure rise

To check for a central retinal vein occlusion

Boat-Shaped Hemorrhage (Preretinal Bleed): What It Means

Boat-shaped hemorrhage is a preretinal bleed with a flat upper border and a curved lower edge.

The blood usually lies beneath the posterior hyaloid or the internal limiting membrane (ILM).

Because the sign localizes the blood, it should prompt a focused workup.

What Boat-Shaped Hemorrhage Looks Like

On fundus examination, the lesion forms a dark red pool with a straight, horizontal top.

The lower margin curves like a keel, which explains the name.

Also, the blood hides the retinal vessels beneath it, while the nearby retina may look normal.

Why the Fluid Level Forms

The blood collects in a confined space in front of the retina, where it can settle.

Gravity then pulls red cells downward, while the plasma stays above them.

As a result, an upright patient shows a horizontal interface.

The curved lower edge probably reflects the boundary of the detached hyaloid or ILM.

Test your knowledge 10 questions from this article

Subhyaloid or Sub-ILM Blood

Ophthalmoscopy cannot always separate the two locations.

Sub-ILM blood often forms a taut dome with a glistening surface.

In contrast, subhyaloid blood may shift with posture.

This difference affects surgery, because a sub-ILM collection may need ILM peeling.

Boat-Shaped Hemorrhage and Other Bleeds

Flame hemorrhages follow the nerve fiber layer, while dot and blot hemorrhages sit deeper.

Subretinal blood lies beneath the retinal vessels and often looks darker.

Vitreous hemorrhage, however, blurs the fundus view more diffusely (see vitreous hemorrhage).

Common Causes of Boat-Shaped Hemorrhage

First, let the history guide the search:

Valsalva retinopathy after straining or vomiting
Proliferative diabetic retinopathy
Retinal vein occlusion with neovascularization
Retinal arterial macroaneurysm
Terson syndrome after intracranial hemorrhage
Leukemia, severe anemia or another blood disorder
Blunt trauma or abusive head trauma in children

History and Examination

First, ask what the patient was doing when the vision changed.

Next, record diabetes, hypertension, anticoagulant use, bruising and recent trauma.

Patients with macular involvement report sudden, painless central vision loss.

Then dilate both eyes, because the fellow eye often provides the clue.

For example, new vessels or laser scars point toward proliferative diabetic retinopathy.

OCT in Boat-Shaped Hemorrhage

OCT shows reflective material in front of the retina, with shadowing beneath it.

However, dense blood can hide the fovea.

Therefore, repeat the scan as the blood clears.

When blood blocks the view, B-scan ultrasound also helps exclude retinal detachment.

Boat-Shaped Hemorrhage as a Red Flag

Severe headache, confusion or reduced consciousness requires urgent neurological assessment.

Terson syndrome may be the first ocular clue to subarachnoid hemorrhage.

Similarly, pallor, fever or unexplained bruising calls for prompt hematological testing.

Never attribute the bleed to Valsalva until the history supports it.

Boat-Shaped Hemorrhage (Preretinal Bleed): What It Means

Observing a Boat-Shaped Hemorrhage

Observation suits small bleeds that spare the fovea.

Sleeping with the head elevated may also help blood settle away from the macula.

However, reabsorption can take weeks or months.

During follow-up, check vision, bleed size and any new neovascularization.

Nd:YAG Hyaloidotomy

A laser opening in the posterior wall lets trapped blood drain into the vitreous.

Case series report rapid visual recovery, although randomized evidence is lacking.

This option works best for a fresh, sizable premacular pool (see Nd:YAG hyaloidotomy).

However, risks include macular hole, retinal detachment and epiretinal membrane.

Vitrectomy for Persistent Blood

Vitrectomy clears dense or nonresolving blood and allows ILM peeling when needed.

It also suits eyes with traction or failed laser drainage.

In Terson syndrome, published series describe useful visual recovery.

However, surgery carries risks such as cataract, retinal tears and endophthalmitis.

Treating the Underlying Cause

Drainage clears the visual axis, but it leaves the bleeding source untreated.

Therefore, proliferative disease still needs panretinal photocoagulation or anti-VEGF therapy.

Anti-VEGF injections may also carry traction risks when fibrovascular tissue is present.

Similarly, a blood disorder needs hematology care.

Counseling Patients

Explain that vision can improve as the blood clears.

However, the final outcome depends on the cause and the underlying macula.

Also, advise the patient to report increasing floaters, flashes or a curtain.

Follow-Up After Boat-Shaped Hemorrhage

First, examine the patient again within one to two weeks, because the bleed may enlarge or rupture into the vitreous.

Next, document the size of the pool with serial photographs or OCT.

Then look for residual epiretinal membrane or macular changes once the blood clears.

Finally, schedule systemic review when the cause remains unclear.

Pitfalls to Avoid

Do not label every bleed as Valsalva without a compatible history
Avoid laser when the blood has clotted
Never skip the fellow eye examination
Recheck the macula once the blood clears

References

Duane TD. Valsalva hemorrhagic retinopathy. Trans Am Ophthalmol Soc. 1972;70:298-313.
Ulbig MW, Mangouritsas G, Rothbauer HH, et al. Long-term results after drainage of premacular subhyaloid hemorrhage into the vitreous with a pulsed Nd:YAG laser. Arch Ophthalmol. 1998;116:1465-1469.
Durukan AH, Kerimoglu H, Erdurman C, et al. Long-term results of Nd:YAG laser treatment for premacular subhyaloid haemorrhage owing to Valsalva retinopathy. Eye. 2008;22:214-218.
Kuhn F, Morris R, Witherspoon CD, Mester V. Terson syndrome: results of vitrectomy and the significance of vitreous hemorrhage in patients with subarachnoid hemorrhage. Ophthalmology. 1998;105:472-477.

Test yourself

A few questions straight from this article.

1 / 10 0 correct

A boat-shaped hemorrhage usually lies in which location?
Boat-shaped hemorrhage is a preretinal bleed that usually lies beneath the posterior hyaloid or the internal limiting membrane, so the sign localizes the blood.
Why does a boat-shaped preretinal hemorrhage have a flat, horizontal upper border?
Blood in a confined preretinal space settles as gravity pulls red cells down while plasma stays above, giving a horizontal interface in an upright patient.
Which feature suggests a sub-ILM rather than subhyaloid location for a boat-shaped hemorrhage?
Sub-ILM blood often forms a taut, glistening dome, while subhyaloid blood may shift with posture; a sub-ILM collection may need ILM peeling.
What distinguishes subretinal blood from a boat-shaped preretinal hemorrhage?
Subretinal blood lies beneath the retinal vessels and often looks darker, whereas a preretinal boat-shaped bleed hides the vessels beneath it.
A patient with a boat-shaped hemorrhage has severe headache and confusion. Which diagnosis must be considered?
Terson syndrome may be the first ocular clue to subarachnoid hemorrhage, so severe headache, confusion or reduced consciousness needs urgent neurological assessment.
Which boat-shaped hemorrhage is most suited to observation?
Observation suits small bleeds that spare the fovea, though reabsorption can take weeks or months and follow-up should check for new neovascularization.
Nd:YAG hyaloidotomy works best for which type of boat-shaped hemorrhage?
A laser opening in the posterior wall lets trapped blood drain into the vitreous, and it works best for a fresh, sizable premacular pool.
Which complication is a recognized risk of Nd:YAG hyaloidotomy for premacular hemorrhage?
Risks of Nd:YAG hyaloidotomy include macular hole, retinal detachment and epiretinal membrane.
After a boat-shaped hemorrhage from proliferative diabetic retinopathy is drained, what further treatment is still needed?
Drainage clears the visual axis but leaves the bleeding source untreated, so proliferative disease still needs panretinal photocoagulation or anti-VEGF therapy.
Why should a patient with a boat-shaped hemorrhage be re-examined within one to two weeks?
Early review within one to two weeks is advised because the bleed may enlarge or break into the vitreous; its size is then followed with photographs or OCT.

Ahmed Ophthalmologist

Writes and reviews the clinical articles on Educate. Every post is checked against peer-reviewed sources before it goes live.