Roth spots are small hemorrhages in the retina identified during an eye examination, characterized by a distinct pale or white center. They are not a disease themselves but rather a physical manifestation pointing to an underlying systemic health issue. Their discovery is considered a diagnostic clue, often prompting a comprehensive medical evaluation to identify serious conditions affecting the blood or blood vessels. These spots serve as a visual indicator of systemic pathology.
The Appearance and Location of Roth Spots
A Roth spot is formally described as a white-centered retinal hemorrhage. During a fundoscopy, which is an examination of the back of the eye, these lesions appear as a red, flame-shaped, or round patch with a noticeable pale center. The red portion signifies blood leaked from a damaged retinal blood vessel, while the pale center is the characteristic feature distinguishing it from other retinal hemorrhages.
These spots are typically located in the posterior pole of the eye, near the optic disc and the macula. Visualizing them requires specialized equipment like an ophthalmoscope or a slit lamp, as they are not visible to the casual observer. The presence of this pale core within the hemorrhage is what distinguishes a Roth spot from other common types of retinal hemorrhages.
How Roth Spots Form
Roth spots form due to damage to the retinal capillaries, leading to the rupture of the vessel wall and leakage of blood into the surrounding tissue (the red part of the lesion). The underlying cause is often dysfunction of the endothelial cells lining the blood vessels.
The distinct pale center is created by material plugging the site of the vessel rupture. This material is primarily composed of a fibrin-platelet thrombus, essentially a tiny blood clot formed by the body’s natural response to stop the bleeding. In systemic diseases, the white center may also consist of immune complexes deposited in the vessel wall, or clumps of abnormal cells, such as those found in leukemia. This white spot represents a localized obstruction or immune reaction.
Primary Indication: Infective Endocarditis
Roth spots hold their greatest historical and diagnostic significance due to their association with infective endocarditis (IE), a serious infection of the inner lining of the heart or its valves. Historically, they were reported frequently, though modern data suggests they are present in less than 5% of all IE cases. Their appearance remains a strong indicator, requiring urgent and aggressive treatment.
In IE, the spots often result from septic microemboli—tiny fragments of infected material that break off from heart valve “vegetations” and travel through the bloodstream. These fragments lodge in the narrow retinal capillaries, causing vessel blockage and rupture.
Other mechanisms involve immunological responses. The immune complex deposition mechanism is a non-infectious phenomenon that causes localized damage to the retinal vessels. This finding is sometimes considered an equivalent to the Janeway lesions or Osler nodes seen on the skin, which are also physical signs of systemic infection and immune response in IE. The presence of Roth spots provides a non-invasive, visual clue that can expedite the diagnosis of a potentially fatal heart infection.
Other Systemic Conditions Associated with Roth Spots
While infective endocarditis is the classic association, Roth spots are a non-specific finding that can be caused by a wide range of other systemic diseases that damage small blood vessels.
Hematological Conditions
Conditions affecting the blood, such as severe anemia or thrombocytopenia (low platelet count), can lead to these hemorrhages. In severe anemia, altered blood viscosity and reduced oxygen-carrying capacity weaken vessel walls, and platelet dysfunction makes it harder to seal small ruptures. Cancers of the blood, such as leukemia, are also commonly linked. In leukemia, the white centers may represent an accumulation of abnormal white blood cells, or increased viscosity caused by a high number of circulating cells can contribute to capillary obstruction and rupture.
Other Systemic Causes
- Chronic conditions: Uncontrolled diabetes and severe hypertension cause long-term damage to the retinal microvasculature (diabetic or hypertensive retinopathy).
- Autoimmune and inflammatory disorders: Systemic lupus erythematosus and collagen vascular diseases can cause Roth spots through vasculitis (inflammation of the blood vessel walls).
- Hypoxia: Conditions involving extreme lack of oxygen, such as severe anoxia or carbon monoxide poisoning, can lead to widespread retinal capillary damage.
The diverse range of causes underscores that a Roth spot is a sign of a final common pathway—damage to the retinal vessel endothelium—rather than a single disease.