BASICS

DESCRIPTION

Retinal microaneurysms are focal dilations of retinal capillaries that appear as tiny red dots in the retina on ophthalmoscopy. They are most commonly found in the macula and posterior pole but may be found in the peripheral retina. They are an indicator of retinal microvascular disease. Microaneurysms may be an isolated finding but are typically found in association with other microvascular abnormalities such as cotton wool spots, retinal hemorrhages, alterations in vessel caliber, telangiectasias, lipid exudates, and retinal edema. The location and associated findings are important indicators of the underlying disorder.

EPIDEMIOLOGY

Incidence

• In diabetics diagnosed before age 30, the prevalence of retinopathy in persons who had diabetes for <5 years was 17% and it increased to 97.5% in persons who had diabetes for 15 or more years (1).

• In diabetics diagnosed after the age of 30, the prevalence of retinopathy in persons who had diabetes for <5 years was 28.8% and it increased to 77.8% in persons who had diabetes for 15 or more years (2).

Prevalence

In nondiabetics, the prevalence of retinopathy found to be 9.8% in persons over 49 years and was significantly related to the presence and severity of hypertension (3).

RISK FACTORS

• Diabetes

• Hypertension

• Abdominal obesity

PATHOPHYSIOLOGY

Damage to retinal capillary pericytes results in weakness and subsequent dilation and saccular outpouching of capillary walls. Microaneurysms are typically found in the inner nuclear layer (4). They may rupture resulting in retinal hemorrhage or leak leading to retinal edema.

ETIOLOGY

• Increased levels of blood glucose

• Retinal ischemia

• Chronic inflammation

COMMONLY ASSOCIATED CONDITIONS

• Diabetic retinopathy

• Hypertensive retinopathy

• Retinal vein occlusions:

– Central retinal vein occlusion (CRVO)

– Branch retinal vein occlusion (BRVO)

DIAGNOSIS

HISTORY

• Microaneurysms are often asymptomatic but may lead to central visual loss or metamorphopsia due to progressive macular edema from chronic leakage. More commonly, microaneurysms are found in association with other retinal vascular abnormalities such as hemorrhage, macular edema, or capillary nonperfusion that commonly cause visual symptoms.

• Microaneurysms may be the earliest detectable sign of diabetic retinopathy.

• In a chronic retinal vein occlusion, microaneurysms may be the only persistent finding once the retinal hemorrhages and edema have resolved.

PHYSICAL EXAM

On direct or indirect ophthalmoscopy, microaneurysms appear as pin-point red dots. It may be difficult to distinguish them from dot retinal hemorrhages without the help of retinal angiography. Typically, microaneurysms are found in the macula and posterior pole when associated with diabetic retinopathy or retinal vein occlusions. When found in the peripheral retina, less common diagnoses such as chronic lymphoma or sickle cell retinopathy should be considered. Red free filters can be used to enhance the visibility of microaneurysms relative to retinal pigmentary changes on ophthalmoscopy.

DIAGNOSTIC TESTS & INTERPRETATION

Lab

Initial lab tests

Evaluation for diabetes and hypertension. See “Differential diagnosis” for additional testing.

Follow-up & special considerations

Depends on the associated condition

Imaging

• Fundus photography (color and red free)

• Fluorescein angiography:

– Very useful in differentiating microaneurysms from small dot retinal hemorrhages

– Early phase of angiogram: Appears as hyperfluorescent dot

– Late phase: Hyperfluorescent dot begins to fade, may find surrounding faint hyperfluorescence indicating leakage

• Optical coherence tomography (OCT)

DIFFERENTIAL DIAGNOSIS

• Diabetic retinopathy

• Retinal vein occlusions

• Hypertensive retinopathy

• Radiation retinopathy

• Idiopathic parafoveal telangiectasia

• HIV

• Sickle cell retinopathy

• Chronic hyperviscosity syndromes (e.g., chronic lymphoma)

TREATMENT

MEDICATION

First Line

Control of underlying disorder such as diabetes or hypertension

Second Line

See treatment of commonly associated conditions.

ADDITIONAL TREATMENT

Issues for Referral

Refer for evaluation of risk factors or for specific treatment of associated conditions by the specialist.

SURGERY/OTHER PROCEDURES

Direct focal laser photocoagulation of microaneurysms when macular edema affects or threatens vision. Fluorescein angiography is often used to guide treatment. Caution must be exercised when treating juxtafoveal aneurysms since this may result in pericentral scotomas.

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Depends on the underlying condition

Patient Monitoring

Self-testing using an Amsler grid blurred vision or metamorphopsia may be useful in following progression or response to treatment.

PATIENT EDUCATION

Depends on risk factors and associated condition

PROGNOSIS

Depends on the associated condition

COMPLICATIONS

See “Commonly associated conditions.” Microaneurysms may cause loss of vision resulting from leakage and macular edema.

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