Platelet count, mean platelet volume, platelet distribution width, and plateletcrit are standard indices of platelet activation that have been studied in retinal vein occlusion (RVO) and its subtypes: branch retinal vein occlusion and central retinal vein occlusion. This systematic review and meta-analysis aimed to assess the association between these platelet parameters and RVO.
We searched for studies investigating the association between these platelet indices and RVO in multiple online databases from inception to August 2020. Mean differences and the associated confidence intervals were obtained and calculated for each included study and pooled using random-effects inverse variance modeling. Meta-regression was used to explore interstudy and intrastudy heterogeneity.
Thousand three hundred and twenty-five unique studies were screened, from which 24 studies encompassing 2,718 patients were included. Mean platelet volume and platelet distribution width were significantly elevated in RVO, with pooled mean differences of 0.45 fL (95% CI 0.24–0.66, P < 0.0001) and 1.43% (95% CI 0.57–2.29, P = 0.0011), respectively. Platelet count and plateletcrit were not significantly associated with RVO. Mean platelet volume was also independently elevated in branch retinal vein occlusion and central retinal vein occlusion.
Mean platelet volume and platelet distribution width are significantly elevated in RVO. Further research is required to explore the independence and potential prognostic significance of these associations.