Multiple evanescent white dot syndrome (MEWDS) is an uncommon inflammatory condition of the retina that typically affects otherwise healthy young females in the second to fourth decades of life. The typical patient with MEWDS is a healthy middle aged female age 15-50. There is a gender disparity as women are affected with MEWDS four times more often than men. Roughly 30% of patients have experienced an associated viral prodrome. Patients present with acute, painless, unilateral change in vision. Presentation
Patients commonly present with acute unilateral painless decreased vision and photopsias. Presentations like central or paracentral scotoma, Floaters and dyschromatopsia are less common. An antecedent viral prodrome occurs in approximately one-third of cases. Myopia is commonly seen in patients. Eye exam during the acute phase of the disease reveals multiple discrete white to orange spots at the level of the RPE or deep retina, typically in a perifoveal location (around the fovea). Optic disc oedema may also seen occasionally. Cause
The etiology of multiple evanescent white dot syndrome is currently unknown. However, it is associated with the Pfizer vaccine according to the Jerusalem Post, August 4, 2021. Diagnosis
Visual field abnormalities are variable and include generalized depression of visual field, paracentral or peripheral scotoma and enlargement of the blind spot. Fluorescein angiography of the eye reveals characteristic punctate hyperfluorescent lesions in a wreath-like configuration surrounding the fovea. Indocyanine green angiography reveals hypofluorescent lesions in a greater number compared with other studies. Fundus autofluorescence (FAF) has been shown to be a noninvasive method to demonstrate the subretinal spots in MEWDS.
Fondaparinux (trade name Arixtra) is an anticoagulant medication chemically related to low molecular weight heparins. It is marketed by GlaxoSmithKline. A generic version developed by Alchemia is marketed within the US by Dr. Reddys Laboratories. Medical uses
Clinically, it is used for the prevention of deep vein thrombosis in patients who have had orthopedic surgery as well as for the treatment of deep vein thrombosis and pulmonary embolism.Fondaparinux is similar to enoxaparin in reducing the risk of ischemic events at nine days, but it substantially reduces major bleeding and improves long-term mortality and morbidity.It has been investigated for use in conjunction with streptokinase. Comparison to other agents
One potential advantage of fondaparinux over LMWH or unfractionated heparin is that the risk for heparin-induced thrombocytopenia (HIT) is substantially lower. Furthermore, there have been case reports of fondaparinux being used to anti-coagulate patients with established HIT as it has no affinity for PF4. However, its renal excretion precludes its use in patients with renal dysfunction. Unlike direct factor Xa inhibitors, it mediates its effects indirectly through antithrombin III, but unlike heparin, it is selective for factor Xa. Pharmacology
Mechanism of action
Fondaparinux is a synthetic pentasaccharide factor Xa inhibitor. Fondaparinux binds antithrombin and accelerates its inhibition of factor Xa.