Sickle cell maculopathy: Identification of systemic risk factors, and microstructural analysis of individual retinal layers of the macula

Abstract

PurposeTo identify systemic risk factors for sickle cell maculopathy, and to analyze the microstructure of the macula of Sickle Cell Disease (SCD) patients by using automated segmentation of individual retinal layers.MethodsThirty consecutive patients with SCD and 30 matched controls underwent spectral-domain optical coherence tomography (SD-OCT) and automated thickness measurement for each retinal layer; thicknesses for SCD patients were then compared to normal controls. Demographic data, systemic data, and lab results were collected for each SCD patient; multivariate logistic regression analysis was used to identify potential risk factors for sickle cell maculopathy.ResultsOngoing chelation treatment (p = 0.0187) was the most predictive factor for the presence of sickle cell maculopathy; the odds were 94.2% lower when chelation was present. HbF level tended to influence sickle cell maculopathy (p = 0.0775); the odds decreased by 12.9% when HbF increased by 1%. Sickle cell maculopathy was detected in 43% of SCD patients as patchy areas of retinal thinning on SD-OCT thickness map, mostly located temporally to the macula, especially in eyes with more advanced forms of sickle cell retinopathy (p = 0.003). In comparison to controls, SCD patients had a subtle thinning of the overall macula and temporal retina compared to controls (most p<0.0001), involving inner and outer retinal layers. Thickening of the retinal pigment epithelium was also detected in SCD eyes (p<0.0001).ConclusionsChronic chelation therapy and, potentially, high levels of HbF are possible protective factors for the presence of sickle cell maculopathy, especially for patients with more advanced forms of sickle cell retinopathy. A subtle thinning of the overall macula occurs in SCD patients and involves multiple retinal layers, suggesting that ischemic vasculopathy may happen in both superficial and deep capillary plexi. Thinning of the outer retinal layers suggests that an ischemic insult of the choriocapillaris may also occur in SCD patients.

Terminologies regarding sickle cell retinopathy and maculopathy

“…It has been shown that low fetal hemoglobin level could increase the risk for sickle cell patients to develop sickle retinopathy [7,8]. However, in contrast to Dell' Arti et al, we found no link between fetal hemoglobin expression level and the presence of maculopathy or retinopathy [9]. This finding could be related to the small number of patients included in our study.…”

Sickle Cell Maculopathy: Prevalence, Associations and Impact on Visual Acuity

“…In a paediatric population, Martin et al [12]found no association with increasing age, gender, or genotype. In adults with sickle cell disease, Dell’Arti et al [9] reported no association between SCM and age, gender, or genotype; in contrast, Mathew et al [8] reported positive associations with both younger age and HbSS genotype. Others have also reported an association with the HbSS genotype [17, 18].…”

<p>Hemoglobin level and macular thinning in sickle cell disease</p>

“…Lim et al recently showed that macular thinning in SCD is associated with age, retinopathy, and HbSS genotype 11. Furthermore, another recent study suggested that high HbF levels and chelation therapy are possible protective factors for the presence of sickle cell maculopathy 12…”