Retinal vein occlusion (RVO) is the second most common cause of vision loss globally, but little is known about how the body’s platelets interact with the condition, if at all. A new meta-analysis suggests mean platelet volume (MPV) and platelet distribution width are significantly elevated in cases of RVO. Higher levels of these markers of platelet activation may be associated with thrombosis risk.

A team examined 24 studies looking into the association between different platelet indices and RVO that included data from a total of 2,718 patients. The researchers observed in the literature significantly elevated MPV and platelet distribution widths in RVO. “MPV measures platelet size and, mechanistically, larger platelets possess more dense granules, and have been linked to increased rate and extent of platelet aggregation, synthesis of thromboxane A2 and serotonin, release of β-thromboglobulin, procoagulant function and expression of adhesion molecules,” the authors wrote,  “Functionally, raised MPV has been related to both venous and arterial thrombotic vascular disorders.”

They noted that mean platelet volume was also elevated in branch and central RVO. Platelet count and plateletcrit, on the other hand, were not significantly associated with RVO.

“Further research is required to explore the independence and potential prognostic significance of these associations,” the study authors wrote in their paper.

Liu Z, Perry LA, Edwards TL. The association between platelet indices and retinal vein occlusion—a systematic review and meta-analysis. Retina. November 25, 2020. [Epub ahead of print].