Retinal nerve fiber layer thickness and retinal vessel calibers in children with thalassemia minor

Does thalassemia truly cause microvascular changes without us noticing? An optical coherence tomography angiography study of the children with beta-thalassemia

PURPOSE

It was aimed to evaluate the retinochoroidal microvascular alterations of pediatric beta-thalassemia patients and investigate the effect of blood transfusion on perfusion among transfusion-dependent thalassemia (TDT), by means of optical coherence tomography angiography (OCTA).

METHODS

In this multicentered, prospective, cross-sectional study, 56 TDT, 14 non-TDT (NTDT), and 63 healthy children were evaluated. The vessel density (VD) in superficial capillary plexus (SCP), deep capillary plexus, radial peripapillary capillary network, choriocapillaris, and the foveal avascular zone area (FAZ) were evaluated by OCTA. Before and after transfusion values ​​of the TDT group were compared, and correlations were made with blood values ​​and iron accumulation.

RESULTS

Foveal and parafoveal zones were significantly thinner among TDT patients, with larger FAZ area. Macula VD of SCP and ppVD was lowest in NTDT group. In the TDT group, a decrease in retinal nerve fiber thickness and ppVD values was detected ​​after transfusion. A negative significant relationship was found between both hemoglobin (Hb), hematocrit (Htc), and ppVD.

CONCLUSIONS

OCTA provides a better insight into retinal and choriocapillaris vascular impairment influenced by tissue hypoxia and oxidative stress in different clinical phenotypes of beta-thalassemia.

Optical coherence tomography findings in patients with transfusion-dependent β-thalassemia

BACKGROUND

Structural ophthalmologic findings have been reported in patients with β-thalassemia due to chronic anemia, iron overload, and iron chelation therapy toxicity in few previous studies. We aimed to investigate structural ocular findings and their relationship with hematological parameters in patients with transfusion-dependent β-thalassemia (TDT).

METHODS

In this cross-sectional study, from January 2018 to January 2019, 39 patients with TDT over the age of 18 participated. Multicolor fundus imaging, optical coherence tomography (OCT), and blue light fundus autofluorescence imaging were performed for all patients and 27 age- and sex-matched controls.

RESULTS

The mean age of patients was 28.6 ± 6.2 years. The central macular thickness and macular thicknesses in all quadrants were significantly thinner in patients than controls (P<0.05). None of the retinal nerve fiber layer (RNFL) measurements were significantly different between TDT patients and controls. There was a significantly negative correlation between hemoglobin with central macula thickness (r=-0.439, P=0.005). All measurements of macular subfield thickness were insignificantly thinner in patients with diabetes mellitus (DM) compared to the non-DM subgroup.

CONCLUSIONS

Macular thickness was significantly thinner in central macula and entire quadrants in TDT patients compared to healthy individuals; however, all RNFL measurement thicknesses were comparable between the two groups. Close monitoring of TDT patients by periodic ophthalmologic examinations with more focus on diabetic patients, patients with severe anemia and iron overload should be warranted.

Retinal and Choriocapillaris Vascular Changes in Patients Affected by Different Clinical Phenotypes of β-Thalassemia: An Optical Coherence Tomography Angiography Study

Simple Summary

β-thalassemia represents a hematological disorder that determines anomalous hemolysis and ineffective erythropoiesis. The patients, undergoing regular lifelong blood transfusion, show an iron overload in the tissues that requires an iron chelation therapy. Both iron accumulation and iron-chelating agents cause ocular manifestations, such as retinal pigment epithelial (RPE) degeneration, RPE mottling, cataract, optic neuropathy and retinal venous tortuosity. In this cross-sectional study, we described the retinal and choriocapillaris microvascular changes in different clinical phenotypes of β-thalassemia that may reflect a tissue hypoxia status and oxidative damages.

Abstract

In this cross-sectional study we assessed the vascular alterations in retinal and choriocapillaris perfusion in patients affected by β-thalassemia, by means of optical coherence tomography angiography (OCTA). A total of 124 eyes of 62 patients (mean age 44.74 ± 5.79 years old) affected by β-thalassemia (transfusion dependent thalassemia (TDT), non-transfusion dependent thalassemia (NTDT) and minor) were compared to 40 eyes of twenty healthy subjects. We evaluated the vessel density (VD) in superficial capillary plexus, deep capillary plexus, radial peripapillary capillary, choriocapillaris and the foveal avascular zone area. The TDT group showed a statistically significant reduction in retinal and choriocapillaris VD respect to controls and the other groups (p < 0.05). No statistically significant difference was found in OCTA parameters between β-thalassemia minor and controls. The NTDT group showed a significant reduction in VD in deep capillary plexus respect to controls and β-thalassemia minor. Significant negative correlations were shown in TDT group between foveal avascular zone and hemoglobin (r = −0.437, p = 0.044) and between ferritin levels and VD of choriocapillaris (r = −0.431, p = 0.038). The OCTA parameters provided a deeper understanding on retinal and choriocapillaris vascular impairment affected by tissue hypoxia levels and the oxidative stress in different clinical phenotypes of the β-thalassemia.

Choroidal Thickness Evaluation in a Transfusion-Dependent Beta-Thalassemia Greek Population

Purpose

To evaluate choroidal thickness in a group of beta-thalassemia patients as assessed by enhanced depth imaging optical coherence tomography.

Patients and Methods

This single-center, observational study involved transfusion-dependent beta-thalassemia (TD-β-thal) patients and healthy controls. One eye of each participant was included in the study. Submacular and peripapillary choroidal thickness, as well as central macular thickness and retinal nerve fiber layer thickness, were evaluated.

Results

Thirty-eight TD-β-thal patients (mean age 42 ± 10.7 years) and 22 healthy controls (mean age 40.3 ± 10.2 years) were included in the study. Subfoveal choroidal thickness was 297.4 ± 74.5 μm in the patient group and 358.4 ± 71.4 μm in the control group (p=0.003). Overall, in the submacular area, the choroid was found to be significantly thinner in the beta-thalassemia population compared to controls in all evaluated points, except for the spot located 1500 μm nasally to the fovea (p=0.093). In the peripapillary area, choroidal thickness was also significantly lower in the thalassemic population compared to the controls (nasal p=0.033, temporal p=0.01, superior p=0.01), except for the inferior quadrant (p= 0.191). We did not observe statistically significant differences in the retinal nerve fiber layer thickness and the central macular thickness between the two groups (p=0.658 and p=0.276, respectively). No correlations with hemoglobin, serum ferritin or iron levels emerged. Patients with the intermediate subtype appeared to have significantly thinner choroids than the ones with thalassemia major.

Conclusion

Our findings suggest that choroidal thickness in the submacular and peripapillary area is significantly reduced in thalassemic patients, compared to healthy individuals. Choroidal thinning in beta-thalassemia possibly reflects the effect of chronic anemia and underlying hemodynamic changes on choroidal tissue.

Retinal nerve fiber layer thickness in children with β-thalassemia major

Purpose

To measure the retinal nerve fiber layer thickness (RNFLT) in children with β-thalassemia major and to compare with healthy controls.

Methods

A total of 47 patients with β-thalassemia major and 51 healthy controls were included. Each subject underwent a standard ophthalmological examination. RNFLT measurements were performed using optical coherence tomography.

Results

Mean age of the patient group and healthy controls were 13.7 ± 2.1 and 14.3 ± 2.2 years, respectively. Mean peripapillary RNFL thickness was 94 µm in the patient group, and 100 µm in the control group (p < 0.01). In patients with β-thalassemia major, RNFL was thinner in all quadrants than control subjects. Within the β-thalassemia major group neither average RNFLT nor each four quadrant RNFLT were correlated with the age, serum ferritin or serum hemoglobin levels (p > 0.05).

Conclusion

In this study, we observed RNFL was thinner in patients with β-thalassemia major. Thinning of RNFL did not correlate with hemoglobin or ferritin levels.