Analysis of optic nerve and macula microvasculature in patients with polycythemia vera using optical coherence...

We aimed to investigate the microvascular structure of the macula and optic nerve head in patients with polycythemia vera (PV) by using optical coherence tomography (OCT) and OCT angiography (OCTA).

Thirty patients with no systemic disease other than PV and 27 healthy individuals between the ages of 18 and 60 were included in the study. The patients underwent a detailed ophthalmologic evaluation including best corrected visual acuity (BCVA), OCT and OCTA measurements, as well as blood tests.

In the macula, superficial capillary plexus (SCP) vascular density (VD) (%) values were found to be significantly lower in the patient group compared to the control group in the inferior half (p = 0.015), parafoveal (superior, temporal, and inferior regions; p = 0.02-0.044) and in the inferior area of the perifovea (p = 0.043). Deep capillary plexus (DCP) VD values were significantly lower in the patient group compared to controls in the total area, as well as in the superior and inferior hemifields and the parafoveal and perifoveal regions (p ≤ 0.008). When radial peripapillary capillary plexus (RPCP) VD values from the optic disc were investigated, significantly lower values were observed in the peripapillary (p = 0.007) and nasal superior (p = 0.004) quadrants in the patient group. Correlation analyses revealed significant negative associations between hematocrit levels and DCP and RPCP VD measurements (all p < 0.05). In addition, the systemic immune-inflammation index (SII) was negatively associated with DCP VD, whereas no significant association was observed with RPCP VD.

Lower SCP, DCP, and RPCP VD values in the patient group may be associated with increased blood viscosity and microcirculatory disturbances in PV. Platelet activation-related vasoconstriction and hyperviscosity-induced slowing of retinal and choriocapillaris blood flow may contribute to this reduction. These findings suggest that OCTA-derived VD measurements may be useful for assessing microvascular involvement in PV.