Study of Retinal and Choroidal Changes in Children with Sickle Cell Disease using Optical Coherence Tomography and Angiography
Authors: ElSadek Tasneem Mahmoud Mohamed , Salman Abdelrahman Gaber , Mohamed Azza , Said Ahmed , Saleh Mohamed Ibrahim , Abdelhafez Nayera Hazaa Khalil 
Published: October 2021

Abstract

Background
Sickle cell disease is known to cause vaso-occlusive peripheral retinopathy as a result of the microvascular insults that occur when sickled erythrocytes affect the retinal and choroidal blood flow. This leads to non-proliferative retinopathy (NPR) and proliferative retinopathy (PR) that can result in vision affection. While sickle cell retinopathy (SCR) in adult patients is well described, less is known about the retinal changes that occur in pediatric patients. To date, most studies have been of adults.

Objective
To screen children with sickle cell disease for the presence of retinal and choroidal changes and to compare the findings with age and sex matched controls by performing structural SD-OCT and OCTA and to correlate between findings. This aimed to assess the prevalence and age of onset of retinopathy among pediatric patients.

Patients and Methods
This cross sectional study was carried out from February 2020 to August 2020 on 30 eyes of patients attending outpatient clinic of Ophthalmology and Pediatric Departments of Ain Shams University Hospitals. Those patients were asked to participate and were enrolled in this study. The ethical standards stated by the ethical committee of Ain Shams University Hospitals were followed. Informed written consent was taken from guardians of all participants.

Results
There was a significant difference between the cases and control groups regarding the SCP and DCP vessel density, FAZ area, vascular disc density, central macular thickness, choroidal thickness, RNFL average thickness, IS/OS and C/D vertical ratio. However, there was no significant difference between the cases two groups regarding the GCC. There was a significant positive correlation between the retinal thickness and the vessel density in the SCP and DCP in the corresponding subfields. There was a positive statistically significant correlation between the Hb F level and the vessel density of the SCP and DCP. Also, there was a negative statistically significant correlation between the Hb F level and the FAZ. There was a negative statistically significant correlation between the Hb S level and the choroidal thickness, GCC and RNFL average thickness. There was also a statistically significant negative correlation between the disease duration and the temporal parafoveal retinal thickness.

Conclusion
SD-OCT and OCTA were able to detect areas of thinning and decreased vascular densities in asymptomatic sickle cell children. This study demonstrated a decreased vessel density on OCTA but a normal retinal thickness on SD-OCT in some of the parafoveal sucfields. This suggests that OCTA can detect microvascular abnormalities and retinopathy early even before it is visible on OCT. Further longitudinal studies are needed to examine the vascular densities and retinal and choroidal thinning in sickle cell disease children and their correlation with the various disease parameters.