Evaluation of the macula and optical nerve head microvasculature in policytemia vera patients with optical coherens tomography angiography

Purpose: The aim of this study was to evaluate macular and optic nerve head microvasculature in polycythemia vera (PV) patients with optical coherence tomography (OCT) and angiography (OCTA) and to compare them with blood tests and healthy controls. Materials and Methods: The data of the patients and healthy control group who applied to Necmettin Erbakan University Faculty of Medicine Hospital Ophthalmology Clinic for ophthalmologic examination between July 2022 and June 2023 were evaluated. Two eyes of 37 patients aged 18-60 years with no systemic disease other than PV and no optic disc or retinal pathology and two eyes of 30 healthy control subjects were included in the study. Patients underwent a complete ophthalmologic examination and blood tests; anterior segment and fundus examination, best corrected visual acuity (BCVA), intraocular pressure, OCT and OCTA measurements were performed with a slit lamp. The collected data were analyzed with SPSS (Statistical Package for Social Sciences) 18.0 package program. Statistical significance level was accepted as p<0.05 for all tests. The study included 74 eyes of 37 patients with PV and 60 eyes of 30 healthy subjects. Hemoglobin (Hb) and hematocrit (Hct) levels were significantly higher in the patient group compared to the control group (p<0.001). Superficial capillary plexus (SCP) vascular density (VD) (%) values of the whole area (p=0.001), superior half (p=0.024), inferior half (p<0.001), parafovea (p=0.004) and perifovea (p=0.002) were lower in the eyes of the patients compared to the eyes of the control group. Deep capillary plexus (DCP) VD (%) values in the whole field (p<0.001), superior half (p<0.001), inferior half (p<0.001), parafovea (p<0.001) and perifovea (p=0.006) were lower in the eyes of the patients compared to the eyes of the control group. DCP VD (%) parafovea (r=-0.287, p=0.001) and temporal perivoea (r=-0.196, p=0.024) values were negatively correlated with Hct level. Radial peripapillary capillary plexus (RPPC) VD (%) values including whole area (p<0.001), peripapillary (p=0.001), superior half (p=0.001), inferior half (p=0.017), nasal superior (p<0.001) and temporal inferior (p=0.027) were lower in the eyes of the patients compared to the eyes of the control group. There was a negative correlation between RPKP VD (%) whole field value and Hct level (r= -0.415, p<0.001). Central macular thickness, temporal parafovea, superior parafovea, nasal parafovea and inferior parafovea measurements of OCT were significantly higher in the patient group compared to the control group (p values were p=0.001, p=0.008, p=0.016, p=0.002, p=0.008, respectively). The temporal inferior retinal nerve fiber layer (RNFL) thickness was significantly lower in the patient group compared to the control group (p=0.020).There was a positive correlation between RNFL and RPKP VD (%) values (r=0.491, p<0.001). Conclusion: In PV patients, OCTA data showed a decrease in RNFL, DCP, and RPKP VD values. Central macular and parafoveal quadrants were found to be thicker in OCT data. RNFL measurement revealed thinning in the temporal inferior area. There was a negative correlation between Hct level and DCP and RPKP. Elevated Hct levels in PV patients were thought to affect the ocular structures at the microvascular level. The use of OCT and OCTA imaging techniques for the detection of ocular effects of the disease may show changes in the microvasculature. With further studies, OCTA may be a part of the ophthalmologic examination in PV patients.Keywords: Retina, Optic disc, Macula, Optical coherence tomography angiography, Polycythemia vera