Evaluation of parafoveal and peripapillary vascular densities using optical coherence tomography angiography in children with thalassemia major

Abstract

Background: Thalassemia major (TM) is an inherited anaemia caused by faulty haemoglobin synthesis. Reducing serum iron levels using iron chelating agents is an important step in the treatment of TM, and the effects on the eye of both the disease and these agents can be determined by regular eye examination. Objectives: We evaluated macular and optic nerve vascular densities in children with TM and compared the results with healthy controls using optical coherence tomography angiography (OCTA). Design: This is a prospective study. Methods: A total of 30 children with TM and 30 healthy controls were included in the study. The area of the foveal avascular zone (FAZ) and the vascular densities (VD) of the optic nerve head (ONH), radial peripapillary capillary (RPC) and deep and superficial retinal vascular networks were measured using OCTA. Results: A statistically significant decrease in VD was observed in the whole image and the parafovea, superior hemi, superior and inferior parts of the superficial capillary plexus and in the whole image and the superior regions of the deep capillary plexus in the TM patient group compared with the control group ( p < 0.05). A significant decrease in VD was also observed in the whole image and the inside disc, peripapillary, nasal, inferonasal and temporal regions of the ONH and in the whole image and the inside disc, peripapillary and inferonasal regions of the RPC network in patients with TM ( p < 0.05). A significant positive correlation was observed between both serum ferritin levels and deferasirox dosage, on one hand, and both the superficial ( p = 0.023 and p = 0.002, respectively) and deep FAZs ( p = 0.015 and p = 0.045, respectively), on the other hand. A negative correlation was also found between the deferasirox dosage and the VDs of the superficial ( p = 0.010) and deep ( p = 0.001) foveal plexuses. Conclusion: Retinal VD and FAZ are affected in patients with TM. OCTA, which can noninvasively measure retinal VD in patients with TM, may be a useful tool for the early detection of retinal microvascular changes that may occur during the course of the disease.