A retinal macroaneurysm is an acquired bulge in the wall of a small artery within the eye’s retina, which is the light-sensitive tissue at the back of the eye. The aneurysm itself is a focal area of weakness and ballooning in the vessel, measuring between 100 and 250 micrometers in diameter. These formations are distinct from microaneurysms, which are much smaller and associated with other retinal conditions.
These vascular dilations are acquired, meaning they develop later in life, and form within the first three branches of the main retinal artery. While many remain stable, they have the potential to leak fluid or blood, leading to complications that can affect vision.
Causes and Associated Conditions
The development of a retinal macroaneurysm is linked to systemic cardiovascular health. Chronic high blood pressure (hypertension) is the most common associated condition. Hypertension exerts persistent force on artery walls, including the retina’s delicate arterioles. Over time, this pressure can weaken the vessel wall, leading to an aneurysm.
Another contributing factor is atherosclerosis. This condition involves the buildup of plaque on artery walls, which causes the vessels to thicken and lose their natural elasticity. These atherosclerotic changes create focal areas of weakness that are susceptible to dilation under pressure, eventually forming a macroaneurysm. The process is similar to arteriosclerotic changes that occur elsewhere in the body.
Certain demographic factors also increase the likelihood of developing a retinal macroaneurysm. The condition is most commonly observed in individuals over 60, with a prevalence in women. The combination of age-related vascular changes and hormonal differences may contribute to this susceptibility. Identifying a macroaneurysm prompts a recommendation for a cardiovascular evaluation to manage any underlying systemic issues.
Symptoms and Visual Changes
Many retinal macroaneurysms are asymptomatic and are discovered incidentally during a routine dilated eye examination. In these cases, the aneurysm is stable, not leaking, and has not impacted the central part of the retina. Patients are often unaware of the condition’s presence until it is pointed out by an ophthalmologist.
When symptoms do occur, they are the result of the macroaneurysm rupturing or leaking, which can lead to a sudden and painless loss of vision. The leakage of fluid into the retinal layers can cause macular edema, which is swelling in the macula, the part of the retina responsible for central vision. This swelling can cause vision to become blurry or distorted, a condition known as metamorphopsia, where straight lines may appear wavy.
If the aneurysm bleeds, it can cause a hemorrhage at various levels within the retina. A significant bleed can also extend into the vitreous, the gel-like substance that fills the eye, leading to the sudden appearance of floaters or a severe obstruction of sight. The specific visual disturbance a person experiences is directly related to the location and extent of the leakage or hemorrhage from the weakened vessel.
Diagnostic Procedures
An eye doctor first identifies a potential retinal macroaneurysm during a dilated fundus examination, which allows for a clear view of the retina and its blood vessels. The aneurysm may appear as a small, round or fusiform dilation along one of the retinal arteries. Further imaging tests are then used to confirm the diagnosis and assess any associated complications.
Fluorescein angiography is a diagnostic test used to visualize the aneurysm and any leakage. During this procedure, a dye is injected into a vein in the arm. As the dye circulates through the retinal arteries, a special camera takes a series of photographs. The macroaneurysm fills with dye and appears as a bright spot, and any leakage from the vessel becomes clearly visible.
Optical Coherence Tomography (OCT) is a non-invasive imaging technique that provides detailed, cross-sectional images of the retina. This test is useful for detecting and quantifying macular edema. An OCT scan can measure the thickness of the retina and show the presence of fluid or blood, helping the doctor determine if the macroaneurysm is actively affecting central vision.
Management and Treatment Approaches
The approach to managing a retinal macroaneurysm depends on its characteristics and effect on vision. If an aneurysm is not leaking or causing visual symptoms, the recommended course is close observation. This monitoring includes regular follow-up appointments with imaging tests like OCT to ensure the macroaneurysm remains stable. Many of these aneurysms eventually close on their own through thrombosis.
For macroaneurysms that are actively leaking and causing macular edema, laser photocoagulation may be considered. This procedure uses a thermal laser to cauterize the tissue surrounding the aneurysm or the aneurysm itself. The goal is to seal the leak, reduce swelling, and prevent further vision loss. This treatment is applied to aneurysms not directly in the foveal center, the most sensitive part of the macula, to avoid damaging central vision.
A common treatment for macroaneurysms causing significant macular edema involves intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) agents. These drugs are injected into the eye and work by blocking a protein that promotes blood vessel leakage and swelling. This treatment can reduce edema and promote the closure of the aneurysm, leading to an improvement in vision. The prognosis is generally favorable, with many patients maintaining or recovering good vision with appropriate and timely management.