Ophthalmology – Retinal Arterial Macroaneurysm

Basics

Description

A retinal arterial macroaneurysm (RAM) is an acquired focal dilatation of a retinal arteriole, usually involving one of the first few orders of arterial branching.

It may be:

• Saccular
• Fusiform

and most often occurs at:

• Arteriolar bifurcations
• Arteriovenous crossings

The superotemporal retinal artery is a commonly recognized location.

RAM may remain asymptomatic or cause visual loss through:

• Retinal hemorrhage
• Vitreous hemorrhage
• Macular edema
• Lipid exudation
• Submacular hemorrhage
• Less commonly exudative retinal detachment

Key Clinical Pattern

The classic patient is:

An older hypertensive woman with sudden painless monocular visual loss and multilayer retinal hemorrhage centered on a retinal arteriole.

However, some RAMs present instead with slowly progressive vision loss from:

Chronic macular exudation and edema.

Epidemiology

RAM usually occurs in:

• Older adults
• Most commonly patients >60 years
• Women more often than men

Disease is usually:

• Unilateral
• Solitary

but:

• Multiple RAMs may occur
• Bilateral disease is possible

Risk Factors

The strongest systemic association is:

Arterial hypertension

Other associations include:

• Atherosclerotic cardiovascular disease
• Dyslipidemia
• Increasing age
• Retinal vein occlusion
• Other systemic vascular disease

Systemic Evaluation

Every newly diagnosed RAM should prompt:

• Blood pressure measurement
• Review of cardiovascular risk factors

and appropriate management of:

• Hypertension
• Dyslipidemia
• Diabetes if present
• Smoking and other vascular risks

Systemic treatment does not immediately eliminate the RAM but reduces overall vascular morbidity.

Pathophysiology

Age-related and hypertensive changes produce:

• Arteriolar wall sclerosis
• Loss of elastic tissue
• Smooth muscle degeneration
• Focal wall weakness

This predisposes a retinal arteriole to:

Focal aneurysmal dilation

Hemorrhagic RAM

A hemorrhagic RAM may rupture suddenly and produce:

• Subretinal hemorrhage
• Intraretinal hemorrhage
• Preretinal/subhyaloid hemorrhage
• Vitreous hemorrhage

Simultaneous hemorrhage at several retinal levels is highly suggestive of:

Retinal arterial macroaneurysm.

Exudative RAM

Some RAMs leak chronically without major rupture.

This produces:

• Macular edema
• Circinate hard exudates
• Intraretinal lipid
• Subretinal fluid

Vision may decline:

Gradually rather than suddenly.

Quiescent RAM

Some macroaneurysms are discovered incidentally and have:

• No hemorrhage
• No significant exudation
• No macular involvement

These often require:

Observation only.

Clinical Presentation

Patients may be:

• Asymptomatic
• Mildly blurred
• Profoundly visually impaired

The presentation depends on whether the RAM causes:

• Hemorrhage
• Exudation
• Macular involvement

Sudden Visual Loss

Acute painless visual loss typically occurs when the RAM ruptures and causes:

• Premacular hemorrhage
• Submacular hemorrhage
• Vitreous hemorrhage

Gradual Visual Loss

Subacute or chronic blurred vision usually results from:

• Macular edema
• Hard exudates
• Chronic subretinal fluid

Fundus Examination

A RAM appears as:

• Round or fusiform arterial dilatation
• Usually along a major retinal arteriole
• Often near an arterial bifurcation

It may be surrounded by:

• Hemorrhage
• Hard exudates
• Retinal edema

Pulsation

Occasionally the aneurysm may appear:

Pulsatile

on ophthalmoscopy or angiography.

This is not required for diagnosis.

Multilevel Hemorrhage

One of the most useful diagnostic clues is hemorrhage occurring simultaneously:

• Beneath the retina
• Within the retina
• In front of the retina
• Into the vitreous

This reflects rupture from an arterial source through several tissue planes.

Subretinal Hemorrhage

Subretinal hemorrhage may extend toward:

The fovea

and can cause permanent photoreceptor/RPE damage if:

• Thick
• Large
• Persistent

Premacular Hemorrhage

Preretinal or sub-ILM blood may produce:

• Sudden profound central visual loss

while leaving peripheral vision relatively preserved.

Vitreous Hemorrhage

If blood enters the vitreous cavity, patients may experience:

• Sudden floaters
• Haze
• Marked visual reduction

Dense vitreous hemorrhage can temporarily obscure the underlying RAM.

Hard Exudates

Chronic vascular leakage may produce:

• Circinate lipid exudation
• Macular hard exudates

These can remain after the macroaneurysm itself has thrombosed.

Diagnosis

Diagnosis is usually made from:

• Clinical examination
• OCT
• Fluorescein angiography when needed

ICGA can be especially helpful when hemorrhage obscures the lesion.

Optical Coherence Tomography

OCT is central to modern evaluation, particularly when the macula is involved.

It can demonstrate:

• Intraretinal fluid
• Cystoid macular edema
• Subretinal fluid
• Hyperreflective hemorrhage
• Subretinal hyperreflective material
• Structural foveal damage

Serial OCT is useful for monitoring:

Response to treatment and spontaneous resolution.

Fluorescein Angiography

FA may show:

• Early arterial filling of the RAM
• Focal hyperfluorescence
• Late leakage
• Adjacent capillary changes

A thrombosed RAM may show:

• Partial filling
• No filling

Indocyanine Green Angiography

ICG angiography is especially useful when hemorrhage obscures the aneurysm.

Its longer wavelength penetrates:

• Blood
• Pigment

better than fluorescein.

This can help distinguish RAM from:

• Polypoidal choroidal vasculopathy
• Choroidal neovascularization

OCT Angiography

OCTA may demonstrate:

• Flow within the macroaneurysm
• Reduced or absent flow after thrombosis

Its usefulness may be limited by:

• Hemorrhage
• Motion artifact
• Segmentation error

B-Scan Ultrasonography

B-scan is not routinely needed for RAM itself.

It may be useful if there is:

• Dense vitreous hemorrhage

to exclude:

• Retinal detachment
• Intraocular mass

Differential Diagnosis

Important differentials include:

• Polypoidal choroidal vasculopathy
• Neovascular AMD
• Retinal vein occlusion
• Diabetic retinopathy
• Retinal capillary hemangioblastoma
• Retinal vasoproliferative tumor
• Coats-like telangiectasia
• Retinal cavernous hemangioma
• Peripheral exudative hemorrhagic chorioretinopathy
• Choroidal neovascularization

RAM vs Polypoidal Choroidal Vasculopathy

RAM

• Lies on a retinal arteriole
• Arterial origin
• Often shows multilayer hemorrhage
• Visible on retinal vascular examination

PCV

• Choroidal vascular lesion
• Often sub-RPE
• Associated with serosanguineous PED
• Best characterized with ICG/OCT

RAM vs Retinal Vein Occlusion

Retinal vein occlusion typically shows:

• Venous dilation
• Venous tortuosity
• Sectoral or diffuse hemorrhage

RAM instead shows:

• A discrete arterial lesion
• Often focal multilayer hemorrhage

RAM vs Neovascular AMD

Neovascular AMD usually has:

• Drusen or other AMD changes
• Subretinal/intraretinal fluid
• CNV-related hemorrhage

RAM should be suspected when hemorrhage is centered on:

A retinal arteriole.

Treatment Principles

Management depends on:

• Visual acuity
• Macular involvement
• Hemorrhage location
• Degree of exudation
• Spontaneous improvement

Many RAMs undergo:

Spontaneous thrombosis and involution

so observation is appropriate in many cases.

Observation

Observation is appropriate when:

• RAM is asymptomatic
• Hemorrhage is away from the fovea
• Macular edema is mild
• Vision is improving
• Spontaneous thrombosis is occurring

Follow-up should include:

• Visual acuity
• Fundus examination
• OCT

Systemic Management

Control:

• Hypertension
• Dyslipidemia
• Other cardiovascular risk factors

This is an essential component of care.

Anti-VEGF Therapy

Intravitreal anti-VEGF has become an important treatment for symptomatic RAM with:

• Macular edema
• Subretinal fluid
• Significant exudation
• Submacular hemorrhage in selected cases

Agents may include:

• Bevacizumab
• Ranibizumab
• Aflibercept

Anti-VEGF Effects

Anti-VEGF may:

• Reduce macular edema
• Reduce subretinal fluid
• Accelerate hemorrhage absorption in some cases
• Improve visual acuity

However:

Many RAMs resolve spontaneously, so not every patient requires injection.

Laser Photocoagulation

Laser may be considered for:

• Persistent exudative RAM
• Macular-threatening leakage
• Chronic edema not resolving spontaneously

Modern practice uses laser more selectively than older treatment algorithms.

Direct Laser

Direct treatment targets:

The macroaneurysm itself

Potential problems include:

• Arterial occlusion
• Distal retinal ischemia
• Hemorrhage
• Vessel damage

Therefore direct laser is used cautiously.

Indirect Laser

Laser can instead be applied to:

• Surrounding leaking capillary bed
• Adjacent areas of exudation

without directly whitening the arterial aneurysm.

This may reduce leakage with less risk of arterial occlusion.

Laser Limitations

Laser should generally be avoided when:

• Hemorrhage blocks visualization
• Lesion lies very near the fovea
• Spontaneous improvement is already occurring

Premacular Hemorrhage

Large premacular hemorrhage may be managed by:

• Observation
• Nd:YAG hyaloidotomy/membranotomy in carefully selected cases
• Vitrectomy

Choice depends on:

• Hemorrhage location
• Duration
• Thickness
• Relationship to ILM/posterior hyaloid
• Visual needs

Nd:YAG Membranotomy

In a selected large premacular subhyaloid or sub-ILM hemorrhage, Nd:YAG laser may create an opening allowing blood to drain into:

The vitreous cavity

where it can clear more rapidly.

Risks include:

• Macular injury
• Retinal break
• Epiretinal membrane
• Persistent vitreous hemorrhage

It should only be performed in appropriately selected eyes.

Submacular Hemorrhage

Large thick subfoveal hemorrhage is particularly vision-threatening because blood can damage photoreceptors through:

• Mechanical separation
• Iron toxicity
• Fibrin contraction

Early displacement may be considered in selected cases.

Pneumatic Displacement

Treatment may include:

• Intravitreal expansile gas
• Often combined with intravitreal or subretinal tPA
• Frequently combined with anti-VEGF

The goal is to:

Displace blood away from the fovea.

Tissue Plasminogen Activator

tPA helps liquefy clot so that gas can displace it.

Routes include:

• Intravitreal
• Subretinal during vitrectomy

Technique depends on:

• Hemorrhage size
• Thickness
• Duration
• Surgeon preference

Vitrectomy

Pars plana vitrectomy may be considered for:

• Nonclearing vitreous hemorrhage
• Dense premacular hemorrhage
• Large recent submacular hemorrhage
• Associated tractional complications

Subretinal tPA During Vitrectomy

For large thick recent submacular hemorrhage, surgery may include:

• PPV
• Subretinal tPA
• Gas tamponade

with the goal of:

Pneumatically displacing blood from beneath the fovea.

This is generally reserved for selected severe cases.

Retinal Detachment

Retinal detachment is uncommon but can occur secondary to:

• Extensive exudation
• Surgical complications
• Other coincident retinal disease

Treatment follows the underlying mechanism.

Follow-Up

Follow-up frequency depends on:

• Macular involvement
• Hemorrhage size
• Edema
• Treatment

Active symptomatic lesions may require review every:

Several weeks initially

with OCT.

Signs of Involution

A macroaneurysm may:

• Thrombose
• Shrink
• Become fibrotic
• Leave arterial kinking
• Leave surrounding lipid or scar

Prognosis

Overall prognosis is often:

Good

because many RAMs thrombose and involute spontaneously.

Visual outcome depends primarily on:

• Foveal hemorrhage
• Macular edema
• Duration of submacular blood
• Chronic lipid exudation
• Macular scar formation

Good Prognostic Features

Better outcomes occur when:

• Macula is spared
• Hemorrhage is limited
• Edema resolves quickly
• RAM thromboses spontaneously

Poor Prognostic Features

Poorer visual outcome is associated with:

• Large subfoveal hemorrhage
• Persistent macular edema
• Dense lipid deposition
• Foveal fibrosis
• Chronic outer retinal damage

Complications

Potential complications include:

• Macular edema
• Submacular hemorrhage
• Premacular hemorrhage
• Vitreous hemorrhage
• Lipid exudation
• Macular scar
• Epiretinal membrane
• Rare retinal detachment
• Permanent central visual loss

Ophthalmology Pearls

• Retinal arterial macroaneurysm is an acquired focal dilatation of a retinal arteriole, usually occurring in older hypertensive women.
• The superotemporal retinal artery is a common site.
• RAM may present as hemorrhagic, exudative, or quiescent disease.
• A particularly helpful clue is multilevel hemorrhage—subretinal, intraretinal, preretinal, and/or vitreous—from a lesion centered on a retinal arteriole.
• Sudden visual loss suggests rupture and hemorrhage, whereas gradual visual decline suggests macular edema or chronic exudation.
• Always check blood pressure and systemic vascular risk factors.
• OCT is the key modern test for macular edema, subretinal fluid, and structural foveal damage.
• FA identifies the arterial lesion and leakage; ICG is particularly useful when blood obscures the macroaneurysm.
• Many RAMs spontaneously thrombose and involute, so observation is appropriate when the macula is not threatened.
• Anti-VEGF therapy is commonly used for symptomatic RAM with macular edema, subretinal fluid, or selected hemorrhagic presentations.
• Laser is now used selectively for persistent exudative leakage, with caution because direct treatment can produce arterial occlusion or distal ischemia.
• Large premacular hemorrhage may occasionally be treated with Nd:YAG membranotomy or vitrectomy in selected cases.
• Large recent submacular hemorrhage may require pneumatic displacement ± tPA or vitrectomy with subretinal tPA.
• The main determinants of final vision are foveal hemorrhage, persistent macular edema, lipid deposition, and macular scarring.
• The retina may recover well after the aneurysm involutes, but prolonged subfoveal blood can cause permanent photoreceptor damage.