We read with great interest the letter written by Guerra et al. . To answer their questions, we defined retinopathy as any stage of proliferative sickle retinopathy displayed by our patients (classification of Goldberg ranging from 1 to 5, ). It is well known that tractional maculopathy can be related to proliferative Sickle cell retinopathy (SCR), and can be involved in a retinal detachment including the macular area. Maculopathy has also been described in several other proliferative retinopathies such as diabetes retinopathy [3, 4]. Nevertheless, our description of sickle cell maculopathy did not include tractional disease. None of our patients had tractional retinal detachment or tractional complication. As a matter of fact, 15 of our patients displayed maculopathy without retinopathy . In our study, we defined maculopathy as any macular thinning under 226 micron, as proposed by the Copernicus Potopol Spectral Domain Ocular Coherence Tomography guidelines .
As ophthalmologists, we thought that we could observe a difference in the onset and risk factors of these two different diseases (i.e., retinopaty and maculopathy). We decided not to perform any invasive examination test, such as fluorescein angiography, if the fundoscopy or wild field retinographies were efficient enough to describe the stage of retinopathy. Angiography is used to evaluate retinal ischemia in order to guide a possible laser treatment when a vitreous hemorrhage is not elective for vitrectomy or in case of extensive sea fans. But no such case was encountered in our patients.
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 .
This finding could be related to the small number of patients included in our study. Only 22 patients of our study were treated by hydroxyurea and, surprisingly, we found no link between this treatment and the level of fetal hemoglobin. No association was found between hydroxyurea and SCD retinopathy or maculopathy. Further studies based on larger patient cohorts are needed to definitively address the role of biological factors in the onset of retinopathy and maculopathy in sickle cell disease.
We thank again Guerra et al.  for their valuable comments, and the editor for giving us the opportunity to answer them.
Leitão Guerra RL , Bastos MA , Salles C Terminologies regarding sickle cell retinopathy. Clin Hemorheol Microcirc. 2018. 10.3233/CH-180462.
Goldberg MF Classification and pathogenesis of proliferative sickle retinopathy. Am J Ophthalmol. 1971;71(3):649–65.
Qamar RMR , Saleem MI , Saleem MF The outcomes of pars plana vitrectomy without endotamponade for tractional retinal detachment secondary to proliferative diabetic retinopathy. Int J Ophthalmol. 2013;6(5): 671–4.
Parikh HA , Kalbag NS , Zarbin MA , Bhagat N Characteristics, Demographics, Outcomes, and Complications of Diabetic Traction Retinal Detachments Treated with Silicone Oil Tamponade. Eur J Ophthalmol. 2016;26(5):497–502.
Beral L , Lemonne N , Romana M , Charlot K , Billaud M , Acomat M , Zorobabel C , Nader E , Etienne-Julan M , David T , Connes P Proliferative retinopathy and maculopathy are two independent conditions in sickle cell disease: Is there a role of blood rheology?1. Clin Hemorheol Microcirc. 2018. 10.3233/CH-180412.
Cohen S-YGA Techniques d’exploration de la rétine. Lavoisier, editor. 2012.
Fox PD , Dunn DT , Morris JS , Serjeant GR Risk factors for proliferative sickle retinopathy. Br J Ophthalmol. 1990;74(3):172–6.
Hayes RJ , Condon PI , Serjeant GR Haematological factors associated with proliferative retinopathy in sickle cell-haemoglobin C disease. Br J Ophthalmol. 1981;65(10):712–7.
Dell’Arti L , Barteselli G , Riva L , Carini E , Graziadei G , Benatti E , Invernizzi A , Cappellini MD , Viola F Sickle cell maculopathy: Identification of systemic risk factors, and microstructural analysis of individual retinal layers of the macula. LewinAS, editor. PLoS One. 2018;13(3):e0193582.