Last reviewed by mvhs13 on August 13th, 2018.
What are Cotton Wool Spots?
Cotton wool spots can be defined as the abnormal findings that are identified on the regular examination of the retina (fundoscopic examination). The name is given due to the fact that these actually resemble cotton wool, being white patches present in different parts of the retina. It is believed that these appear in patients who have suffered nerve fiber damage, the cytoplasm commonly contained in the axon of the neurons having accumulated within the different layers of the nerve fiber.
Because of the above-mentioned changes, the affected nerves suffer from an ischemic process and the axonal transport is actually reduced. The damage occurring at the level of the nerve fibers is believed to be caused by an inflammatory process within the eye retina. It is important to understand that the cotton wool spots are not actually locations where the ischemia has occurred at the level of the retina. Instead, they show areas where obstruction has appeared, as a result of axoplasmic material accumulating.
According to the specialists in the field, cotton wool spots are accompanied by other pathological changes, such as infarcts occurring in the small blood vessels of the eye and intra-retinal bleeding. It is also worth mentioning that the cotton wool spots might become less visible with the passing of time.
Cotton Wool Spots Symptoms
In regard to the clinical manifestations, it is important to understand that, other from the identification on the retina, cotton wool spots are often asymptomatic. In the situation that they have expanded so as to involve the fovea, it is possible that the patient suffers from vision loss (impaired vision). Also, if the patient suffers from an underlying condition, such as diabetes or hypertension, he/she will present the characteristic symptoms for the condition in question (systemic symptoms).
Causes of Cotton Wool Spots
There are a number of medical conditions in which cotton wool spots are present among other findings. Patients who suffer from diabetes and high blood pressure present an increased risk for such problems. In the situation that one suffers from malignant hypertension, the cotton wool spots are presented in high numbers (proliferation). As for patients who suffer from diabetes, the appearance of cotton wool spots is suggestive of pre-proliferative retinopathy, which refers to the damage of the retina as a result of diabetes (high risk of blindness). There are other conditions in which these spots might be present, including: HIV, central retinal vein occlusion and Purtscher’s retinopathy (in rare situations).
It is also possible to classify the causes into a number of categories. For example, the ischemic causes that might lead to the appearance of cotton wool spots include: hypertension, diabetes, retinal vein occlusion, ocular ischemic syndrome and radiation. Certain immune & inflammatory conditions, such as lupus, scleroderma and arteritis might cause similar problems. Infectious causes, apart from HIV, include: cat-scratch disease, leptospirosis and rocky mountain spotted fever. There also embolic causes: cardiac valvular disease, endocarditis and rheumatic heart disease. Neoplastic causes can lead to cotton wool spots as well, with leukemia, lymphoma and metastatic cancer being among the most common. The interferon commonly administered for retinopathy can lead to the appearance of these spots, while trauma and idiopathic causes have also been considered.
Treatment of Cotton Wool Spots
There is no specific treatment recommended for the cotton wool spots. In general, both the treatment & management measures regard the underlying condition. Once the underlying condition is successfully treated or kept under control, the cotton wool spots are going to disappear on their own. In general, it can take between six and twelve weeks for these spots to go away, while this period might be prolonged in patients who have been diagnosed with diabetic retinopathy.