Dear Editor:

We read with great interest the article "Mean platelet volume in patients with retinal artery occlusion" by Şahin et al.⁽¹⁾ published in your journal. In that very interesting, well-designed, and well-presented study, Şahin and coworkers found that mean platelet volume (MPV) values were significantly higher in the patient group than in the control group; they also showed that MPV was an independent predictor of retinal artery occlusion (RAO).

RAO is a rare cause of irreversible visual impairment seen particularly in older age groups and is caused by thrombotic and/or embolic events⁽¹⁾. Changes in platelet activation play an important role in the pathogenesis of thromboembolic and/or inflammatory diseases. Platelet function plays a key role in the control of inflammatory response and thromboembolic disorders while also undergoing changes secondary to this process. MPV has a meaningful place in the evaluation of indicators of the size and activity of platelets^(1,2). Parameters, such as red cell distribution width (RDW) and neutrophil to lymphocyte ratio (NLR) of the underlying hemogram test, are important in characterizing thromboembolic disorders. Studies have shown that RDW and/or NLR values were higher in patients with retinal vein occlusion⁽³⁾ and coronary artery occlusion⁽⁴⁾ than in control patients.

MPV is a readily measurable laboratory marker used to evaluate systemic inflammation and/or thromboembolic disorders. On the other hand, the use of MPV is limited by several factors, including hypertension, diabetes mellitus, metabolic syndrome, obesity, hyperlipidemia, renal/hepatic dysfunction, thyroid abnormalities, hematological disorders, blood transfusion, malignancies, cardiac or heart valve diseases, asthma, chronic obstructive pulmonary disease, peripheral/cerebral vascular disease, anemia, B12 and folic acid deficiency, history of smoking and alcohol consumption, and the use of any medication related to inflammatory/thromboembolic status of patients; thus, measurement of the MPV can be important in these situations^(1,5). Nevertheless, it is very significant that the MPV increased over time in the EDTA-anticoagulated samples. Because their study was retrospectively designed, the authors cannot precisely describe how much time elapsed before measuring the MPV values, but we wish to point out that delaying blood sample testing may lead to changes in results in MPV measurements⁽⁵⁾.

In conclusion, this study led us to consider that MPV may be assessed as a marker to identify patients with thromboembolic disorders. We believe that MPV and the other markers, NLR and RDW, should be evaluated together in future multi-directional prospective studies in patients with RAO.