Purpose: The aim of this study was to clarify whether the clinical, laboratory and genetic aspects of sickle cell disease (SCD) influence the occurrence of vessel alterations in the conjunctiva and retina. Methods: A total of 102 SCD patients underwent biomicroscopical and retinal examination, in addition to evaluations of haemoglobin (Hb) and haematocrit (Ht) levels, fetal haemoglobin (HbF) estimations, serum creatinine and albuminuria levels, glomerular filtration rate (GFR) values, phenotypes, β -globin gene haplotypes and α -thalassaemia. The relationship between ocular vessel alterations and clinical, laboratory and genetic features were evaluated using chisquared or Fisher tests and logistic regression analysis. In 13 patients on enalapril treatment, a second ophthalmological evaluation was performed after a 12- month period to evaluate the longitudinal effect of the drug on ocular vessels. Results: Conjunctival vessel alteration (CVA) was not influenced by age, gender, HbF estimation, serum creatinine and albuminuria levels, GFR values, β -globin gene haplotypes or α -thalassaemia. However, increased frequencies of CVA were found in patients with Hb ≤ 9.0 g/dl, Ht ≤ 26.7% and sickle cell anaemia (SS) phenotype. Retinal vessel alteration (RVA) was identi-fied only in patients aged 17 years or older. Enalapril did not demonstrate ocular vessel amelioration after 12- months of daily use. Conclusion: The results indicate that lower Hb and Ht levels and SS phenotype are risk factors for CVA, and age over 17 years may be risk factors for RVA in SCD patients. Purpose: The aim of this study was to clarify whether the clinical, laboratory and genetic aspects of sickle cell disease (SCD) influence the occurrence of vessel alterations in the conjunctiva and retina. Methods: A total of 102 SCD patients underwent biomicroscopical and retinal examination , in addition to evaluations of haemoglobin (Hb) and haematocrit (Ht) levels, fetal hemoglobin (HbF) estimations, serum creatinine and albuminuria levels, glomerular filtration rate (GFR) values, phenotypes, β-globin gene haplotypes and α -thalassaemia. The relationship between ocular vessel alterations and clinical, laboratory and genetic features were evaluated using chisquared or Fisher tests and logistic regression analysis. In 13 patients on enalapril treatment, a second ophthalmological evaluation was performed after a 12- month period to evaluate the longitudinal effect of the drug on ocular vessels. Results: Conjunctival vessel alteration (CVA) was not affected by age, gender, HbF est However, the increased frequencies of CVA were found in patients with Hb ≤ 9.0 g / dl, Ht ≤ 26.7% and sickle cell anaemia (SS), imation, serum creatinine and albuminuria levels, GFR values, β-globin gene haplotypes or alpha- Phenotype. Retinal vessel alteration (RVA) was identi-fied only in patients aged 17 years or older. Enalapril did not demonstrate ocular vessel amelioration after 12- months of daily use. Conclusion: The results indicate that lower Hb and Ht levels and SS phenotype are risk factors for CVA, and age over 17 years may be risk factors for RVA in SCD patients.