Acquired retinal macroaneurysm

From EyeWiki



Disease Entity

Etiology

An acquired retinal macroaneurysm (retinal arterial macroaneurysm/RAM) forms when arteriosclerosis leads to weakening of the arteriolar wall and consequently, the arterial wall develops an outpouching that results in a macroaneurysm.

Risk Factors

Systemic hypertension, cardiovascular disease, and hyperlipidemia are risk factors for acquired retinal macroaneurysm formation. Females are more likely to be affected in their sixth or seventh decade.

General Pathology

Histopathologically, there is distension of the affected arteriolar wall, often with surrounding lipid, hemosiderin, blood and proliferation of fibroglial cells.

Diagnosis

History

There may be no symptoms at all in an eye with an acquired retinal macroaneurysm that has not bled or leaked into the macula. In some eyes, there may be sudden painless loss of vision.

Physical examination

A complete ophthalmologic examination with pupillary dilation should be performed.

Symptoms

The patient may be asymptomatic or may notice a painless sudden decrease in vision.

Clinical diagnosis

On ophthalmoscopy, fusiform or round outpouchings or dilations may be evident along one of the retinal arterioles. About 90% are unilateral. The macroaneurysm is usually located in the posterior pole at one of the first 3 bifurcations of the retinal arterioles, with the superotemporal artery being the most common. Usually, RAM is solitary. RAM usually occurs as a saccular arteriolar dilation at the arterio-venous crossing or bifucration. Retinal hemorrhage is seen in 50% cases.

In some eyes, multilayer hemorrhage is often noted----subretinal, subhyaloid/preretinal, intraretinal and vitreous hemorrhage may be present, obscuring the macroaneuyrsm itself. These locations of hemorrhage is characteristic in eyes with an acquired retinal macroaneurysm that has bled. If a vitreous hemorrhage is present, Bscan ultrasonography may demonstrate the multilayer hemorrhage as well.

Diagnostic procedures

Fluorescein angiography can be very useful in making the diagnosis, particularly in those eyes that have associated hemorrhage where the macroaneurysm may light up with the fluorescein where the macroaneurysm usually fills uniformly in the early arterial phase. In the late phase frames, the wall of the aneurysm may demonstrate leakage or staining. Incomplete filling of RAM is due to thrombosis. In some eyes, the blood is so extensive that the macroaneurysm is not visible even on fluorescein angiography since the blood blocks the fluorescence.

Optical coherence tomography is used to document and follow the progression of the macular edema, and subretinal/preretinal hemorrhage.

Laboratory test

Patients with an acquired retinal macroaneurysm should have a lipid panel evaluated by their internist as well as a blood pressure evaluation.

Differential diagnosis

The following entities should be considered in the differential diagnosis of acquired retinal macroaneurysm when associated with hemorrhage: branch retinal vein occlusion, retinal telangiectasis, proliferative diabetic retinopathy, neovascular age-related macular degeneration when associated with hemorrhagic pigment epithelial detachment. Hemorrhage at multiple levels may also be seen with trauma and anemia.

Management

General treatment

Instruct the patient to follow-up with the patient's internist to monitor and treat blood pressure and any lipid abnormalities. Smoking should be discouraged.

Some cases of RAM may may involute spontaneously due to thrombosis and fibrosis which may appear before or after the development of exudates or hemorrhage.

Observation

  • If vision and macula are not threated by an isolated RAM.

Surgery

Laser photocoagulation- when RAM threatens or involved fovea with or without visual decline. Laser may be applied to the RAM itself or the surrounding area or both. There is a risk of vitreous hemorrhage and branch retinal arteriolar occlusion after laser.

YAG laser hyaloidotomy may be considered in preretinal (prefoveal) hemorrhage.

Intravitreal gas (C3F8/SF6) with recombinant tissue plasminogen and prone position may be helpful in thick subretinal bleed involving the macula from arcade to arcade.

Vitrectomy may be needed if the vitreous hemorrhage does not resolve.

A case series of 37 patients documented closure of 95% complicated RAM lesions after intravitreal bevacizumab.

Complications

Complications related to the presence of the retinal macroaneurysm include

  • Chronic leakage-lipid deposition in the foveal center, macular edema,
  • subfoveal hemorrhage, intraretinal, preretinal and vitreous hemorrhage.
  • rarely epiretinal membrane or choroidal neovascular membrane

Additional Resources

  • AAO, Basic and Clinical Science Course, Section 12: Retina and Vitreous, 2010-11.
  • American Academy of Ophthalmology. Refractive Management/Intervention: Acquired retinal macroaneurysm Practicing Ophthalmologists Learning System, 2017 - 2019 San Francisco: American Academy of Ophthalmology, 2017.