Sickle Cell Disease and the Eye: Old and New Concepts

Comparison of Retinal Blood Flow Parameters in Sickle Cell Disease at Steady State and Healthy Subjects Using Doppler Optical Coherence Tomography

BACKGROUND AND OBJECTIVE

Sickle cell disease (SCD) is a vascular disease that may affect the retina. This study aimed to evaluate differences in average velocity (AV, mm/s), blood flow (BF, μL/min) and vessel diameter (VD, μm) from the temporal retinal arcades in SCD compared to healthy eyes using Doppler optical coherence tomography (DOCT).

PATIENTS AND METHODS

A cross-sectional study was conducted between 2021 and 2023. The DOCT scan was located at the superior and inferior temporal vessel arcades of all subjects. Differences between the two groups were assessed.

RESULTS

Thirty-nine healthy eyes and 36 SCD eyes were imaged. The median of AV, BF, and VD were 1.4, 2.5, and 1.3 times higher in SCD eyes compared to healthy eyes in the superotemporal arteries (P = 0.002, P = 5.0 × 10-3, P = 4.0 × 10-6, respectively). Similar findings were observed for superotemporal veins and inferotemporal veins.

CONCLUSION

Eyes with SCD eyes exhibited significantly elevated retinal vascular flow parameters compared to healthy eyes. [Ophthalmic Surg Lasers Imaging Retina 2025;56:220-227.].

Automated Quantitative Assessment of Retinal Vascular Tortuosity in Patients with Sickle Cell Disease

Objective

To quantitatively assess the retinal vascular tortuosity of patients with sickle cell disease (SCD) and retinopathy (SCR) using an automated deep learning (DL)-based pipeline.

Design

Cross-sectional study.

Subjects

Patients diagnosed with SCD and screened for SCR at an academic eye center between January 2015 and November 2022 were identified using electronic health records. Eyes of unaffected matched patients (i.e., no history of SCD, hypertension, diabetes mellitus, or retinal occlusive disorder) served as controls.

Methods

For each patient, demographic data, sickle cell diagnosis, types and total number of sickle cell crises, SCD medications used, ocular and systemic comorbidities, and history of intraocular treatment were extracted. A previously published DL algorithm was used to calculate retinal microvascular tortuosity using ultrawidefield pseudocolor fundus imaging among patients with SCD vs. controls.

Main Outcome Measures

Cumulative tortuosity index (CTI).

Results

Overall, 64 patients (119 eyes) with SCD and 57 age- and race-matched controls (106 eyes) were included. The majority of the patients with SCD were females (65.6%) and of Black or African descent (78.1%), with an average age of 35.1 ± 20.1 years. The mean number of crises per patient was 3.4 ± 5.2, and the patients took 0.7 ± 0.9 medications. The mean CTI for eyes with SCD was higher than controls (1.06 ± vs. 1.03 ± 0.02, P < 0.001). On subgroup analysis, hemoglobin S, hemoglobin C, and HbS/beta-thalassemia variants had significantly higher CTIs compared with controls (1.07 vs. 1.03, P < 0.001), but not with sickle cell trait variant (1.04 vs. 1.03 control, P = .2). Univariable analysis showed a higher CTI in patients diagnosed with proliferative SCR, most significantly among those with sea-fan neovascularization (1.06 ± 0.02 vs. 1.04 ± 0.01, P < 0.001) and those with >3 sickle cell crises (1.07 ± 0.02 vs. 1.05 ± 0.02, P < 0.001).

Conclusions

A DL-based metric of cumulative vascular tortuosity associates with and may be a potential biomarker for SCD and SCR disease severity.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Preferential Sites of Retinal Capillary Occlusion in Sickle Cell Disease

Purpose

To assess the preferential sites of retinal capillary occlusion at the parafovea in patients with sickle cell disease (SCD) using optical coherence tomography angiography (OCT-A).

Methods

OCT-A scans from 107 patients with SCD and 51 race-matched unaffected controls were obtained using a commercial spectral domain-OCT system. At least eight sequential 3 × 3 mm scans centered at the fovea were acquired and averaged for image analysis. In each participant, foveal avascular zone (FAZ) metrics, perivascular, and quadrant-based capillary densities were measured on the averaged full vascular retinal OCT-A slab. Intermittent capillary perfusion at the FAZ border was also identified using sequential registered OCT-A scans.

Results

Perivascular and quadrant-based capillary densities were significantly lower in SCD groups (Kruskal-Wallis tests; P < 0.001) with preferential sites of capillary nonperfusion occurring along periarteriolar aspect of the vascular bed and at the temporal aspect of the fovea. FAZ perimeter and acircularity index were significantly higher in SCD groups (Kruskal-Wallis tests; P ≤ 0.05). However, no significant differences in FAZ area between unaffected control and SCD groups were observed (Kruskal-Wallis test; P = 0.08). The number of capillary segments with intermittent perfusion was higher in the SCD groups.

Conclusions

Our findings suggest that the periarteriolar aspect of the vascular bed is the preferential site of retinal capillary occlusion in patients with SCD with more involvement of the temporal aspect of the parafovea.

Retrospective Cohort Study of Sickle Cell Disease and Large Vessel Retinal Vascular Occlusion Risk in a National United States Database

OBJECTIVE

To determine if differences exist in the risk of developing large vessel retinal vascular occlusions in patients with sickle cell states.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Patients with sickle cell disease (SCD) or trait evaluated by an ophthalmologist were compared with matched controls without SCD or sickle cell trait (SCT) also evaluated by an ophthalmologist.

METHODS

This study used deidentified data from a national database (2006-2024), using International Classification of Diseases 10 codes to select for retinal vascular occlusions. Propensity score matching was performed with respect to age, sex, race, ethnicity, smoking, hypertension, diabetes, dyslipidemias, and obesity, resulting in hemoglobin SS (HbSS), hemoglobin SC (HbSC), and SCT cohorts and matched control cohorts.

MAIN OUTCOME MEASURES

Risk ratios (RRs) and 95% confidence intervals (CIs) of retinal vascular occlusion diagnosis, including central retinal artery occlusion (CRAO), branch retinal artery occlusion (BRAO), central retinal vein occlusion, branch retinal vein occlusion, and corneal dystrophy as a negative control, given SCD or SCT.

RESULTS

After propensity score matching, HbSS (n = 10 802; mean age ± standard deviation, 38.6 ± 20.6 years), HbSC (n = 4296, 34.3 ± 17.8 years), and SCT (n = 15 249, 39.8 ± 23.7 years) cohorts were compared with control cohorts (n = 10 802, 38.7 ± 20.7 years; n = 4296, 34.6 ± 18.0 years; n = 15 249, 39.9 ± 23.8 years, respectively). Patients with SCD (HbSS) had higher risk of developing any retinal vascular occlusion (RR, 2.33; 95% CI, 1.82-3.00), CRAO (RR, 2.71; 95% CI, 1.65-4.47), and BRAO (RR, 4.90; 95% CI, 2.48-9.67) than matched controls. Patients with HbSC disease had higher risk (RR, 3.14; 95% CI, 1.95-5.06) of developing any retinal vascular occlusion than matched controls without SCD. Patients with SCT did not have higher risk of developing retinal vascular occlusions (RR, 1.01; 95% CI, 0.81-1.26) than matched controls.

CONCLUSIONS

In a retrospective cohort study, patients with HbSS SCD have an increased risk of developing retinal vascular occlusions, and more specifically CRAO and BRAO, compared with patients without SCD.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Pachychoroid neovascular membrane in a patient with sickle cell disease trait

PURPOSE

To describe a rare presentation of pachychoroid neovascular membrane in a patient with sickle cell trait and the accuracy of ruling out hemoglobinopathies in the presentation of pachychoroid spectrum.

METHODS

The patient was subjected to physical examinations, multimodal images (fluorescein angiography, optical coherence tomography), hemoglobin electrophoresis, and peripheral blood smear, documenting sickle cell trait. The management included laser treatment to target non-perfusion areas, along with a single dose of anti-VEGF.

RESULTS

A 45-year-old male patient with diagnosis of pachychoroid neovascularization treated for 6 years with multiple anti VEGF injections in the left eye. A detailed clinical evaluation included hypochromic conjunctiva, peripheral vascular occlusion with non-perfusion areas led us to suspect sickle cell disease retinopathy. The images of fluorescein angiography showed peripheral arteriovenous anastomosis with non-perfusion areas; the optical coherence tomography revealed a thinner neuroepithelium with a thicker choroid; also, hemoglobin electrophoresis and peripheral blood smear documenting sickle cell trait. The chosen management was photocoagulation of the peripheral retina on the non-perfusion areas and anti VEGF without neovascular activity recurrence in the follow up period.

CONCLUSION

Although sickle cell trait is considered a mild form of this pathology without serious retinal manifestations, it has to be noted that in the context of pachychoroid spectrum diseases is a trigger that could perpetuate retinal ischemia and neovascular activity.

The molecular mechanism responsible for HbSC retinopathy may depend on the action of the angiogenesis-related genes ROBO1 and SLC38A5

HbSC disease, a less severe form of sickle cell disease, affects the retina more frequently and patients have higher rates of proliferative retinopathy that can progress to vision loss. This study aimed to identify differences in the expression of endothelial cell-derived molecules associated with the pathophysiology of proliferative sickle cell retinopathy (PSCR). RNAseq was used to compare the gene expression profile of circulating endothelial colony-forming cells from patients with SC hemoglobinopathy and proliferative retinopathy (n = 5), versus SC patients without retinopathy (n = 3). Real-time polymerase chain reaction (qRT-PCR) was used to validate the RNAseq results. A total of 134 differentially expressed genes (DEGs) were found. DEGs were mainly associated with vasodilatation, type I interferon signaling, innate immunity and angiogenesis. Among the DEGs identified, we highlight the most up-regulated genes ROBO1 (log2FoldChange = 4.32, FDR = 1.35E-11) and SLC38A5 (log2FoldChange = 3.36 FDR = 1.59E-07). ROBO1, an axon-guided receptor, promotes endothelial cell migration and contributes to the development of retinal angiogenesis and pathological ocular neovascularization. Endothelial SLC38A5, an amino acid (AA) transporter, regulates developmental and pathological retinal angiogenesis by controlling the uptake of AA nutrient, which may serve as metabolic fuel for the proliferation of endothelial cells (ECs) and consequent promotion of angiogenesis. Our data provide an important step towards elucidating the molecular pathophysiology of PSCR that may explain the differences in ocular manifestations between individuals with hemoglobinopathies and afford insights for new alternative strategies to inhibit pathological angiogenesis.

Identifying Clinical Predictors of Proliferative Sickle Cell Retinopathy

PURPOSE

To identify systemic and/or ophthalmologic predictors of proliferative sickle retinopathy.

METHODS

Cross-sectional study comparing clinical, laboratory, and structural choriorretinal aspects between sickle cell disease patients with and without proliferative retinopathy. Patients underwent complete systemic and ophthalmologic evaluation. Enhanced depth spectral domain optical coherence tomography with choroidal binarization and optic coherence tomography angiography were performed and choriorretinal vascular components were compared.

RESULTS

Forty-five eyes from 45 sickle cell patients were included. Ninety-one percent of patients were diagnosed with sickle cell retinopathy, 29% with proliferative retinopathy. Mean corpuscular volume, lactate dehydrogenase, and percentage of fetal hemoglobin were reduced in the subgroup of patients with proliferative retinopathy when compared with patients without proliferative retinopathy (p ≤ 0.001; p = 0.04; p ≤ 0.001, respectively). The best predictor of proliferative retinopathy was mean corpuscular volume (AUC = 0.842; p = 0.001), followed by the percentage of fetal hemoglobin (AUC = 0.763, p = 0.009) and lactate dehydrogenase (AUC curve = 0.706; p = 0.039). No differences were found between groups in the quantitative analysis of retinal vascularization using OCTA and choroidal vascularization using OCT (p ≥ 0.05).

CONCLUSION

Fetal hemoglobin and mean corpuscular volume may be good predictors of proliferative sickle retinopathy. The association between proliferative retinopathy and reduced levels of lactate dehydrogenase and mean corpuscular volume points to hypoxia and not hemolysis as a possible driving force in its pathophysiology.

Rare Cause of Acute Loss of Vision in a Patient With Sickle Cell Trait

Sickle cell disease (SCD) is a prevalent inherited blood disorder with various ocular manifestations, including sickle cell retinopathy (SCR), characterized by retinal microcirculation impairment and ischemic complications. We present the case of a 21-year-old male with sickle cell trait who experienced a sudden, painless loss of vision in his left eye. Ophthalmologic examination revealed vitreous hemorrhage and neovascularization, indicating SCR. Initial treatment with hydroxyurea and exchange transfusions led to partial improvement. However, due to persistent vitreous hemorrhage, the patient underwent a vitrectomy. The sickle cell trait affects a large global population, and its retinopathy is a rare but severe complication. The pathogenesis and risk factors for SCR are similar to those for SCD. The diagnosis of SCR is established through fundoscopic examination and graded based on Goldberg's classification. Management involves a multidisciplinary approach targeting systemic illness and visual defects, including hydroxyurea, photocoagulation, anti-vascular endothelial growth factors, and vitrectomy. Awareness, early diagnosis, and timely intervention are essential to preventing vision-threatening complications in sickle cell trait patients with SCR.

Comparative transcriptome analysis of endothelial progenitor cells of HbSS patients with and without proliferative retinopathy

Among sickle cell anemia (SCA) complications, proliferative sickle cell retinopathy (PSCR) is one of the most important, being responsible for visual impairment in 10-20% of affected eyes. The aim of this study was to identify differentially expressed genes (DEGs) present in pathways that may be implicated in the pathophysiology of PSCR from the transcriptome profile analysis of endothelial progenitor cells. RNA-Seq was used to compare gene expression profile of circulating endothelial colony-forming cells (ECFCs) from HbSS patients with and without PSCR. Furthermore, functional enrichment analysis and protein-protein interaction (PPI) networks were performed to gain further insights into biological functions. The differential expression analysis identified 501 DEGs, when comparing the groups with and without PSCR. Furthermore, functional enrichment analysis showed associations of the DEGs in 200 biological processes. Among these, regulation of mitogen-activated protein (MAP) kinase activity, positive regulation of phosphatidylinositol 3-kinase (PI3K), and positive regulation of Signal Transducer and Activator of Transcription (STAT) receptor signaling pathway were observed. These pathways are associated with angiogenesis, cell migration, adhesion, differentiation, and proliferation, important processes involved in PSCR pathophysiology. Moreover, our results showed an over-expression of VEGFC (vascular endothelial growth factor-C) and FLT1 (Fms-Related Receptor Tyrosine Kinase 1) genes, when comparing HbSS patients with and without PSCR. These results may indicate a possible association between VEGFC and FLT1 receptor, which may activate signaling pathways such as PI3K/AKT and MAPK/ERK and contribute to the mechanisms implicated in neovascularization. Thus, our findings contain preliminary results that may guide future studies in the field, since the molecular mechanisms of PSCR are still poorly understood.

Laser therapy for retinopathy in sickle cell disease

BACKGROUND

Sickle cell disease (SCD) includes a group of inherited haemoglobinopathies affecting multiple organs including the eyes. Some people with SCD develop ocular manifestations. Vision-threatening complications are mainly due to proliferative sickle retinopathy, which is characterised by proliferation of new blood vessels. Laser photocoagulation is widely applicable in proliferative retinopathies. It is important to evaluate the efficacy and safety of laser photocoagulation in the treatment of proliferative sickle retinopathy (PSR) to prevent sight-threatening complications.

OBJECTIVES

To evaluate the effectiveness of various techniques of laser photocoagulation therapy in SCD-related proliferative retinopathy.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. Date of last search: 4 July 2022. We also searched the following resources (26 June 2022): Latin American and Caribbean Health Science Literature Database (LILACS); WHO International Clinical Trials Registry Platforms (ICTRP); and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials comparing laser photocoagulation to no treatment in children and adults with SCD.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility and risk of bias of the included trials; we extracted and analysed data, contacting trial authors for additional information. We assessed the certainty of the evidence using the GRADE criteria.

MAIN RESULTS

We included three trials (414 eyes of 339 children and adults) comparing the efficacy and safety of laser photocoagulation to no therapy in people with PSR. There were 160 males and 179 females ranging in age from 13 to 67 years. The trials used different laser photocoagulation techniques; one single-centre trial employed sectoral scatter laser photocoagulation using an argon laser; a two-centre trial employed feeder vessel coagulation using argon laser in one centre and xenon arc in the second centre; while a third trial employed focal scatter laser photocoagulation using argon laser. The mean follow-up periods were 21 to 32 months in one trial, 42 to 47 months in a second, and 48 months in the third. Two trials had a high risk of allocation bias due to the randomisation method for participants with bilateral disease; the third trial had an unclear risk of selection bias. One trial was at risk of reporting bias. Given the unit of analysis is the eye rather than the individual, we chose to report the data narratively. Using sectoral scatter laser photocoagulation, one trial (174 eyes) reported no difference between groups for complete regression of PSR: 30.2% in the laser group and 22.4% in the control group. The same trial also reported no difference between groups in the development of new PSR: 34.3% of lasered eyes and 41.3% of control eyes (very low-certainty evidence). The two-centre trial using feeder vessel coagulation, only presented data at follow-up for one centre (mean period of nine years) and reported the development of new sea fan in 48.0% in the treated and 45.0% in the control group; no statistical significance (P = 0.64). A third trial reported regression in 55% of the laser group versus 28.6% of controls and progression of PSR in 10.5% of treated versus 25.7% of control eyes. We graded the evidence for these two primary outcomes as very low-certainty evidence. The sectoral scatter laser photocoagulation trial reported visual loss in 3.0% of treated eyes (mean follow-up 47 months) versus 12.0% of controlled eyes (mean follow-up 42 months) (P = 0.019). The feeder vessel coagulation trial reported visual loss in 1.14% of the laser group and 7.5% of the control group (mean follow-up 26 months at one site and 32 months in another) (P = 0.07). The focal scatter laser photocoagulation trial (mean follow-up of four years) reported that 72/73 eyes had the same visual acuity, while visual loss was seen in only one eye from the control group. We graded the certainty of the evidence as very low. The sectoral scatter laser trial detected vitreous haemorrhage in 12.0% of the laser group and 25.3% of control with a mean follow-up of 42 (control) to 47 months (treated) (P ≤ 0.5). The two-centre feeder vessel coagulation trial observed vitreous haemorrhage in 3.4% treated eyes (mean follow-up 26 months) versus 27.5% control eyes (mean follow-up 32 months); one centre (mean follow-up nine years) reported vitreous haemorrhage in 1/25 eyes (4.0%) in the treatment group and 9/20 eyes (45.0%) in the control group (P = 0.002). The scatter laser photocoagulation trial reported that vitreous haemorrhage was not seen in the treated group compared to 6/35 (17.1%) eyes in the control group and appeared only in the grades B and (PSR) stage III) (P < 0.05). We graded evidence for this outcome as low-certainty. Regarding adverse effects, only one occurrence of retinal tear was reported. All three trials reported on retinal detachment, with no significance across the treatment and control groups (low-certainty evidence). One trial reported on choroidal neovascularization, with treatment with xenon arc found to be associated with a significantly higher risk, but visual loss related to this complication is uncommon with long-term follow-up of three years or more. The included trials did not report on other adverse effects or quality of life.

AUTHORS' CONCLUSIONS

Our conclusions are based on the data from three trials (two of which were conducted over 30 years ago). Given the limited evidence available, which we assessed to be of low- or very low-certainty, we are uncertain whether laser therapy for sickle cell retinopathy improves the outcomes measured in this review. This treatment does not appear to have an effect on clinical outcomes such as regression of PSR and development of new incidences. No evidence is available assessing efficacy in relation to patient-important outcomes (such as quality of life or the loss of a driving licence).  Further research is needed to examine the safety of laser treatment compared to other interventions such as intravitreal injection of anti-vascular endothelial growth factors (VEGFs) . Patient-important outcomes as well as cost-effectiveness should be addressed.

Insights into Sickle Cell Disease through the Retinal Microvasculature: Adaptive Optics Scanning Light Ophthalmoscopy Correlates of Clinical OCT Angiography

PURPOSE

Clinical OCT angiography (OCTA) of the retinal microvasculature offers a quantitative correlate to systemic disease burden and treatment efficacy in sickle cell disease (SCD). The purpose of this study was to use the higher resolution of adaptive optics scanning light ophthalmoscopy (AOSLO) to elucidate OCTA features of parafoveal microvascular compromise identified in SCD patients.

DESIGN

Case series of 11 SCD patients and 1 unaffected control.

PARTICIPANTS

A total of 11 eyes of 11 SCD patients (mean age, 33 years; range, 23-44; 8 female, 3 male) and 1 eye of a 34-year-old unaffected control.

METHODS

Ten sequential 3 × 3 mm parafoveal OCTA full vascular slab scans were obtained per eye using a commercial spectral domain OCT system (Avanti RTVue-XR; Optovue). These were used to identify areas of compromised perfusion near the foveal avascular zone (FAZ), designated as regions of interest (ROIs). Immediately thereafter, AOSLO imaging was performed on these ROIs to examine the cellular details of abnormal perfusion. Each participant was imaged at a single cross-sectional time point. Additionally, 2 of the SCD patients were imaged prospectively 2 months after initial imaging to study compromised capillary segments across time and with treatment.

MAIN OUTCOME MEASURES

Detection and characterization of parafoveal perfusion abnormalities identified using OCTA and resolved using AOSLO imaging.

RESULTS

We found evidence of abnormal blood flow on OCTA and AOSLO imaging among all 11 SCD patients with diverse systemic and ocular histories. Adaptive optics scanning light ophthalmoscopy imaging revealed a spectrum of phenomena, including capillaries with intermittent blood flow, blood cell stasis, and sites of thrombus formation. Adaptive optics scanning light ophthalmoscopy imaging was able to resolve single sickled red blood cells, rouleaux formations, and blood cell-vessel wall interactions. OCT angiography and AOSLO imaging were sensitive enough to document improved retinal perfusion in an SCD patient 2 months after initiation of oral hydroxyurea therapy.

CONCLUSIONS

Adaptive optics scanning light ophthalmoscopy imaging was able to reveal the cellular details of perfusion abnormalities detected using clinical OCTA. The synergy between these clinical and laboratory imaging modalities presents a promising avenue in the management of SCD through the development of noninvasive ocular biomarkers to prognosticate progression and measure the response to systemic treatment.

Risk factors associated with sickle cell retinopathy: findings from the Cooperative Study of Sickle Cell Disease

BACKGROUND

Sickle cell retinopathy (SCR) is one of the most important ocular manifestations of sickle cell disease (SCD). This study aims to assess the prevalence of SCR in SCD, identify risk factors for its development and progression to proliferative sickle cell retinopathy (PSCR), and evaluate the potential implications of these results on clinical practice.

METHODS

This research is a secondary analysis of patients diagnosed with SCD from the epidemiological, multicenter Cooperative Study of Sickle Cell Disease (CSSCD). We included all patients who completed a full ophthalmic evaluation. We identified clinical and laboratory SCD characteristics associated with SCR using multivariate logistic regression models. Proliferative sickle cell retinopathy (PSCR) was diagnosed according to the Goldberg classification system.

RESULTS

Of the 1904 study participants with SCD who met the inclusion criteria, 953 (50.1%) had retinopathy; of which 642 (67.3%) had bilateral disease. SCR was associated with older age (p < 0.001), history of smoking (p = 0.001), hematuria (p = 0.050), and a lower hemoglobin F (HbF) level (p < 0.001). PSCR risk increased with smoking (p = 0.005), older age (p < 0.001) higher hemoglobin level (p < 0.001) and higher white blood cell count (p = 0.011). Previous blood transfusion (p = 0.050), higher reticulocyte count (p = 0.019) and higher HbF level (p < 0.001) were protective factors against the development of PSCR. Ocular symptoms were associated with progression to PSCR in patients with SCR (p = 0.021).

CONCLUSION

In this cohort of individuals with SCD, half of the participants had signs of SCR. Smoking and blood hemoglobin level were the two modifiable risk factors associated with increased retinopathy progression. Screening to identify the different stages of retinopathy, actively promoting smoking cessation, and optimizing the hematological profile of patients with SCD should guide treatment protocols designed to prevent the vision-threatening complications of the disease.

Co-occurrence of oculocutaneous albinism type 2 and mild sickle cell disease explained by HbS/βthal genotype in an individual from the Democratic Republic of Congo

Oculocutaneous albinism type 2 (OCA2) is a pigmentation disorder characterized by hypopigmentation of the skin, hair and eyes and ocular features. Sickle cell disease (SCD) is caused either by homozygosity of the beta globin gene variant c.20A > T/p.Glu6Val giving rise to severe anemia or by combined abnormal hemoglobins (HbS/βthal) leading to mild SCD. We report a 45 years old female patient from the Democratic Republic of Congo affected with these two disorders. She presented with creamy white skin and numerous pigmented patches called dendritic freckles, nystagmus, foveal hypoplasia grade 2, photophobia and very poor visual acuity. Sequencing of the OCA2 gene identified the common exon 7 deletion and a new pathogenic variant c.1444A > C/p.Thr482Pro. She had mild SCD with a total Hb level of 101 g/l. Hbβ sequencing identified variants c.20A > T giving rise to HbS and c.315 + 1 G > A characteristic of β-thalassemia. A heterozygous 3.7 kb deletion of the α globin gene was also found. The combined Hbβ/α globin genotype explains the mild SCD phenotype. Co-occurrence of OCA2 and SCD raises the question whether the patient's phenotype simply results from the addition of the two diseases' phenotypes or whether interaction between the two diseases modulates the phenotype of each other.

Retinal atrophy and markers of systemic and cerebrovascular severity in homozygous sickle cell disease

Introduction

While paramacular retinal atrophy (PRA) is known to be found in 48% of eyes of adults and 42% of eyes of children with homozygous SCD (SS-SCD), the aim of this study is to assess the association between PRA and red blood cell (RBC) deformability, hematological markers and brain imaging abnormalities in SS-SCD.

Methods

This study is a subset of DREAM2, a prospective observational study performed between August 2015 and August 2016. Children (5–17 years) with SS-SCD and no history of large vessel vasculopathy, were included. Ophthalmological characteristics including visual acuity, fundus examination, OCT of central and temporal retina (with several retinal thickness measurements) were explored in relation with RBC deformability (ektacytometry), hematological and biochemical (hemolysis parameters), and neurological (cerebral oxygenation estimated by Near Infrared Spectroscopy, brain magnetic resonance imaging) investigations.

Results

17 children (5 boys; mean age: 13 years) with complete ophthalmological investigations were included in the analysis; 8 exhibited PRA. RBC deformability was found to be significantly lower in children with PRA for measurements made at 1.69 Pa (0.16 a.u ± 0.02 vs 0.21 a.u ± 0.03, p = 0.02) and above, as well as cerebral oxygenation (59.25% ± 9.9 vs 71.53% ± 4.9, p = 0.02). A significant positive correlation was found between temporal retinal thickness and hemoglobin level (ρ = 0.65, p = 0.007), hematocrit (ρ = 0.53, p = 0.04) and RBC deformability at 3 Pa (ρ = 0.75, p = 0.005) and above.

Conclusions

These results suggest that PRA could be an early marker of systemic severity and cerebral oxygenation in SCD. Whether it could help predicting cerebral vasculopathy requires further investigations.

Salmon patch-associated vitreous hemorrhage in non-proliferative sickle cell retinopathy masquerading as infectious uveitis

PURPOSE

To report three cases of non-proliferative sickle cell retinopathy (NPSR) with vitreous hemorrhage masquerading as infectious uveitis.

OBSERVATIONS

Three patients were referred from ophthalmologists to our practices with clinical findings suggestive of infectious uveitis. The first patient was referred for new-onset floaters in both eyes, bilateral vitritis and dome-shaped lesions on B-scan ultrasound. He was initially treated for tuberculosis uveitis due to a positive purified protein derivative test. The second patient was referred with floaters and hazy vision in the setting of recent fever and headache and was also reported to have vitritis and unilateral yellow vitreoretinal lesions on fundoscopy. She was initially treated for toxoplasmosis and endogenous endophthalmitis. The third patient presented with flashes, floaters, and decreased vision four months after a ring-enhancing lesion was found on brain imaging, and was found to have unilateral vitritis with yellow vitreoretinal lesions. He was initially started on topical steroids and cycloplegics empirically for uveitis. All patients were ultimately diagnosed as having manifestations of NPSR, including vitreous hemorrhage, and dehemoglobinized salmon patch hemorrhages.

CONCLUSIONS AND IMPORTANCE

NPSR can occasionally masquerade as infectious uveitis. Obtaining a detailed history with relevant ancillary testing, along with performing a careful physical exam to recognize important clues, can help the physician arrive at the correct diagnosis in these equivocal cases.

Retinal and choroidal thickness in pediatric patients with sickle cell disease: a cross-sectional cohort study

BACKGROUND

To measure the retinal/choroidal thicknesses in the macular area of asymptomatic pediatric patients with sickle cell disease (SCD).

METHODS

This cross-sectional cohort study included 40 children (79 eyes) with SCD and 19 control patients (36 eyes). All subjects underwent spectral-domain optical coherence tomography (SD-OCT) with enhanced-depth imaging OCT. Generalized Estimating Equations (GEE) were applied to compare the outcomes between groups. P ≤ 0.05 was considered significant.

RESULTS

The choroidal thickness in the macular area in the study subfields was significantly thinner in the SCD eyes compared with control eyes (subfoveal subfield and temporal parafoveal subfield, p < 0.0001; nasal parafoveal subfield, p < 0.0001 temporal perifoveal subfield, p < 0.0001; and nasal perifoveal subfield, p < 0.0001). The variations in the retinal thickness were not significant.

CONCLUSION

EDI-OCT showed that the macular choroidal thickness is thinner in asymptomatic pediatric patients with SCD.

Retinopathy in Egyptian patients with sickle cell disease: A cross-sectional study

ABSTRACT

Sickle cell disease (SCD) is a disorder that causes red blood cells to become sticky and rigid. Sickle cells can block blood flow in small blood vessels depriving the eye of oxygen and cause damage. This is called sickle retinopathy that can progress to severe proliferative sickle cell retinopathy, bleeding into the eye, detachment of the retina or even loss of vision.To assess ocular manifestations and detect frequency of retinopathy in patients with SCD.Cross-sectional study was conducted on 32 patients with SCD. They were 22 males and 10 females with mean age of 12 years. Routine investigations as well as ophthalmological examination including visual acuity, fluorescein angiography and optical coherence tomography were done.We found that 8 patients (25%) suffered from proliferative retinopathy, 10 patients (31%) showed tortuous retinal veins, while 14 patients (44%) were normal. All patients showed macular thinning on optical coherence tomography examination.We concluded that frequency of retinopathy in patients with SCD is more than expected and it was higher in patients who started transfusion at a later age. More attention should be paid for this problem and close observations and follow up is strongly needed.

Acute chest syndrome in sickle cell disease/HBE patient, A case report

The presented case will shed some light on one of the rarest complications of HBSE disease, which is acute chest syndrome, and will highlight the management of that complication.

Do We Store Packed Red Blood Cells under "Quasi-Diabetic" Conditions?

Red blood cell (RBC) transfusion is one of the most common therapeutic procedures in modern medicine. Although frequently lifesaving, it often has deleterious side effects. RBC quality is one of the critical factors for transfusion efficacy and safety. The role of various factors in the cells’ ability to maintain their functionality during storage is widely discussed in professional literature. Thus, the extra- and intracellular factors inducing an accelerated RBC aging need to be identified and therapeutically modified. Despite the extensively studied in vivo effect of chronic hyperglycemia on RBC hemodynamic and metabolic properties, as well as on their lifespan, only limited attention has been directed at the high sugar concentration in RBCs storage media, a possible cause of damage to red blood cells. This mini-review aims to compare the biophysical and biochemical changes observed in the red blood cells during cold storage and in patients with non-insulin-dependent diabetes mellitus (NIDDM). Given the well-described corresponding RBC alterations in NIDDM and during cold storage, we may regard the stored (especially long-stored) RBCs as “quasi-diabetic”. Keeping in mind that these RBC modifications may be crucial for the initial steps of microvascular pathogenesis, suitable preventive care for the transfused patients should be considered. We hope that our hypothesis will stimulate targeted experimental research to establish a relationship between a high sugar concentration in a storage medium and a deterioration in cells’ functional properties during storage.

Hemoglobinopathies: ocular manifestations in children and adolescents

Hemoglobinopathies are genetic disorders that lead to abnormal structure of the hemoglobin molecule. Sickle cell disease, the most common inherited blood disorder, is characterized by defective oxygen transport. Almost every part of the eye can be affected by sickle cell disease; however, proliferative sickle cell retinopathy is the primary cause of vision loss, either from vitreous hemorrhage or retinal detachment. Here we review the various manifestations of hemoglobinopathies on the eyes of children and adolescents, with a specific focus on sickle cell disease and its different phenotypes. Newer, more sensitive ophthalmological imaging modalities, including ultra-widefield fluorescein angiography, spectral-domain optical coherence tomography, and optical coherence tomography angiography, are available. These sensitive modalities allow for a more thorough examination of the retinal periphery where sickle cell retinopathy is often present. Utilization of such modalities will help with the early detection of the disease in children, which provide a better understanding of the pathogenesis of the disease and guide future screening and treatment regimens.

Diabetic and Retinal Vascular Eye Disease

The retinal vasculature is the only neurovascular system directly visible to the human eye, easily evaluated by fundoscopy and many imaging modalities. This window allows physicians to diagnose and treat retinal pathologies and detect systemic diseases including diabetes, hypertension, hypercoagulable/hyperviscosity syndromes, and vasculitis. Diabetic retinopathy is the most common retinal vascular disease, followed by retinal vein and artery occlusion. Patients with these conditions require medical optimization to prevent further damage to the eyes and to the other organs. Both the internists and medical subspecialists play a crucial role in the prevention, detection, evaluation, and management of vision-threatening retinal vascular diseases.

Sickle Cell Maculopathy: Microstructural Analysis Using OCTA and Identification of Genetic, Systemic, and Biological Risk Factors

PURPOSE

To identify genetic, systemic, and biological factors associated with the occurrence of sickle cell maculopathy (SCM). To evaluate microvascular macular alterations using optical coherence tomography angiography (OCTA) in sickle cell disease (SCD).

DESIGN

Cross-sectional study.

METHODS

One hundred fifty-one eyes of 78 adult SCD patients (43 HbSS, 30 HbSC, 4 S/β⁺, and 1 HbS Lepore) and 40 eyes of 20 healthy controls underwent spectral-domain optical coherence tomography (SDOCT) and OCTA using Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany). We analyzed the occurrence of SCM, the foveal avascular zone (FAZ) area, and the severity of macular ischemia and studied their relationships with genetic, systemic, and biological parameters using multivariate logistic regression analysis.

RESULTS

Maculopathy occurred in 66 eyes (44%), and more frequently in HbSS patients (71%, P = .004). Multivariate analysis identified HbSS genotype and lower prothrombin ratio (PR) as independently associated with SCM (P = .01). Proliferative sickle cell retinopathy was also associated with SCM (P = .02). FAZ enlargement was associated with higher lactate dehydrogenase level (P = .02). Macular ischemia was more severe in patients with lower hemoglobin level (P = .004) and lower PR (P = .01). No flow areas were identified with OCTA even in eyes with no macular thinning (36 eyes, 42%) and appeared more frequently in the temporal superior subfield (36%).

CONCLUSIONS

HbSS genotype, abnormal coagulation and hemolysis increase the risk of SCM. OCTA provides valuable criteria to identify potential risk factors of SCM. OCTA also improves detection of early microvascular changes before the onset of macular thinning.

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

AIMS

To investigate the prevalence of sickle cell maculopathy (SCM), and associations with age, sex, genotype, proliferative sickle cell retinopathy (PSR) stage, and the impact on visual acuity.

METHODS

Age, sex, and visual acuity were recorded and spectral domain OCT and ultra-wide-field images of the macula and retina were reviewed in a consecutive series of 74 adults with sickle cell disease.

RESULTS

The median age was 37 years (range 19-73 years) and 36 cases (48.6%) were male. SCM was present in at least 1 eye of 40 cases (54.1%) or in 67 of all eyes (42.3%). SCM prevalence was 54.8%, 62.5%, and 25% for the HbSS, HbSC, and HbS/BThal or other genotypes, respectively. SCM was observed in 41 (39.4%) of the eyes with PSR stages 0, 1, and 2, and in 21 (51.2%) of the eyes with PSR stages 3, 4, and 5, respectively. Mild visual impairment or worse was present in 3 eyes (4.8%) with SCM but this was secondary to other pathology.

CONCLUSION

SCM is a frequent finding in the eyes of adults with sickle cell disease. The prevalence is similar for the HbSS and HbSC genotypes and is not related to the PSR stage. High-contrast distance visual acuity is typically preserved.

Polymorphisms in Inflammatory Genes Modulate Clinical Complications in Patients With Sickle Cell Disease

Sickle cell disease (SCD), the most common monogenic disease worldwide, is marked by a phenotypic variability that is, to date, only partially understood. Because inflammation plays a major role in SCD pathophysiology, we hypothesized that single nucleotide polymorphisms (SNP) in genes encoding functionally important inflammatory proteins might modulate the occurrence of SCD complications. We assessed the association between 20 SNPs in genes encoding Toll-like receptors (TLR), NK cell receptors (NKG), histocompatibility leukocyte antigens (HLA), major histocompatibility complex class I polypeptide-related sequence A (MICA) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), and the occurrence of six SCD clinical complications (stroke, acute chest syndrome (ACS), leg ulcers, cholelithiasis, osteonecrosis, or retinopathy). This study was performed in a cohort of 500 patients. We found that the TLR2 rs4696480 TA, TLR2 rs3804099 CC, and HLA-G, rs9380142 AA genotypes were more frequent in patients who had fewer complications. Also, in logistic regression, the HLA-G rs9380142 G allele increased the risk of cholelithiasis (AG vs. AA, OR 1.57, 95%CI 1.16-2.15; GG vs. AA, OR 2.47, 95%CI 1.34-4.64; P = 0.02). For SNPs located in the NKG2D loci, in logistic regression, the A allele in three SNPs was associated with a lower frequency of retinopathy, namely, rs2246809 (AA vs. GG: OR 0.22, 95%CI 0.09-0.50; AG vs. GG: OR 0.47, 95%CI 0.31-0.71; P = 0.004, for patients of same origin), rs2617160 (AT vs. TT: OR 0.67, 95%CI 0.48-0.92; AA vs. TT: OR 0.45, 95%CI 0.23-0.84; P = 0.04), and rs2617169 (AA vs. TT: OR 0.33, 95%CI 0.13-0.82; AT vs. TT: OR 0.58, 95%CI 0.36-0.91, P = 0.049, in patients of same SCD genotype). These results, by uncovering susceptibility to, or protection against SCD complications, might contribute to a better understanding of the inflammatory pathways involved in SCD manifestations and to pave the way for the discovery of biomarkers that predict disease severity, which would improve SCD management.

Sight threatening vitreous haemorrhage and retinal detachment in a patient with sickle cell disease

We report a case of sight threatening vitreous haemorrhage and retinal detachment as complication of sickle cell disease (SCD). A 35 years old female Nigerian patient had presented to ophthalmology clinic of Princess Marina Hospital, Botswana, with two weeks history of poor vision in the left eye. The loss of vision was due to vitreous haemorrhage and retinal detachment which was confirmed by direct and indirect ophthalmoscopy and B-Scan ultrasound. Prior to presentation, patient didn't have any follow up by an ophthalmologist as part of regular medical care for patients with SCD. We emphasize the importance of regular follow up for early detection, treatment and prevention of complication associated with sickle cell disease.

[Role of OCT-angiography in the management of sickle cell retinopathy]

INTRODUCTION

Sickle cell retinopathy is the main ophthalmologic complication of sickle cell syndrome. Optical coherence tomography (OCT) and optical coherence tomography-angiography (OCT-A) permit demonstration of central retinal involvement. The goal of this study is to determine whether central retinal involvement is predictive of peripheral retinal ischemia.

MATERIALS AND METHODS

We carried out a retrospective study of 31 patients with sickle cell disease who underwent a complete ophthalmologic examination. We focused on capillary density of the superficial and deep plexuses and the central avascular surface by OCT-A, and retinal layer thickness by OCT. All of the findings obtained by OCT-A and OCT were classified according to the Goldberg stages on fluorescein angiography.

RESULTS

A thinning of the mean and temporal deep plexus capillary layer as well as a loss of the temporal density of the superficial plexus capillaries are significantly higher in the case of proliferative sickle cell retinopathy (P=<0.05). A significant negative correlation is observed between the mean and temporal density of the superficial (R=-0.31; P=0.02 and R=-0.43; P=0.0009) and deep plexus capillaries (R=-0.39; P=0.003 et R=-0.43; P=0.0009) and the Goldberg stage in fluorescein angiography.

CONCLUSION

The study of the temporal capillary densities of the superficial and deep plexuses on OCT angiography may prove to be a useful tool for the ophthalmologist in order to diagnose patients at risk for proliferative sickle cell retinopathy.

Relationship between retinal vessel tortuosity and oxygenation in sickle cell retinopathy

Background

Reduced retinal vascular oxygen (O₂) content causes tissue hypoxia and may lead to development of vision-threatening pathologies. Since increased vessel tortuosity is an early sign for some hypoxia-implicated retinopathies, we investigated a relationship between retinal vascular O₂ content and vessel tortuosity indices.

Methods

Dual wavelength retinal oximetry using a commercially available scanning laser ophthalmoscope was performed in both eyes of 12 healthy (NC) and 12 sickle cell retinopathy (SCR) subjects. Images were analyzed to quantify retinal arterial and venous O₂ content and determine vessel tortuosity index (VTI) and vessel inflection index (VII) in circumpapillary regions. Linear mixed model analysis was used to determine the effect of disease on vascular O₂ content, VTI and VII, and relate vascular O₂ content with VTI and VII. Models accounted for vessel type, fellow eyes, age and mean arterial pressure.

Results

Retinal arterial and venous O₂ content were lower in SCR (O_2A = 11 ± 4 mLO₂/dL, O_2V = 7 ± 2 mLO₂/dL) compared to NC (O_2A = 18 ± 3 mLO₂/dL, O_2V = 13 ± 3 mLO₂/dL) subjects (p < 0.001). As expected, O₂ content was higher in arteries (15 ± 5 mLO₂/dL) than veins (10 ± 4 mLO₂/dL) (p < 0.001), but not different between eyes (OD: 12 ± 5 mLO₂/dL; OS:13 ± 5 mLO₂/dL) (p = 0.3). VTI was not significantly different between SCR (0.18 ± 0.07) and NC (0.15 ± 0.04) subjects, or between arteries (0.18 ± 0.07) and veins (0.16 ± 0.04), or between eyes (OD: 0.18 ± 0.07, OS:0.17 ± 0.05) (p ≥ 0.06). VII was significantly higher in SCR (10 ± 2) compared to NC subjects (8 ± 1) (p = 0.003). VII was also higher in veins (9 ± 2) compared to arteries (8 ± 5) (p = 0.04), but not different between eyes (OD: 9 ± 2; OS: 9 ± 2) (p = 0.2). There was an inverse linear relationship between vascular O₂ (13 ± 5 mLO₂/dL) content and VII (9 ± 2) (β = -0.5; p = 0.02).

Conclusions

The findings augment knowledge of relationship between retinal vascular oxygenation and morphological changes and potentially contribute to identifying biomarkers for assessment of retinal hypoxia due to SCR and other retinopathies.

Spectral domain optical coherence tomography findings in Turkish sickle-cell disease and beta thalassemia major patients

Purpose

To assess probable structural changes using spectral domain optical coherence tomography (SD-OCT) on sickle-cell disease (SCD) and beta thalassemia major (B-TM) patients, without any retinal abnormalities.

Methods

This cross-sectional study included 32 B-TM, 34 SCD patients, and 44 healthy controls. One of the eyes of all participants was evaluated for SD-OCT and choroidal thickness, retinal nerve fiber layer (RNFL) thickness, central macular thickness (CMT), ganglion cell complex (GCC).

Results

Age, gender, and intraocular pressure (IOP) were not statistically different between the three groups. Hemoglobin (Hgb), hematocrite (Htc), and ferritin levels were not statistically different between the SCD and B-TM groups. Choroidal thickness at the subfoveal region was statistically higher in the control group (353.79 ± 71.93) than in the B-TM (317.41 ± 53.44) and SCD (283.21 ± 63.27) groups. In addition, it was statistically higher in the B-TM group than the SCD group (P = 0.05). CMT did not differ among the three groups, average RNFL was only significantly thinner in SCD than in controls, and GCC thickness was significantly thinner in SCD than in controls and B-TM.

Conclusion

In both diseases, we can show early structural changes even if proliferative or non-proliferative retinopathy or other ocular manifestations were not developed yet.

Multifocal electroretinogram findings in sickle cell maculopathy

BACKGROUND

The aim of the present work was to describe and compare multifocal electroretinogram findings (mfERG) between patients with sickle cell disease (SCD) without clinical sign of maculopathy and controls (HbAA).

METHODS

Both HbSS (homozygous SCD) and HbSC (compound heterozygous SCD) patients, the two most frequent SCD genotypes, were included. All individuals underwent a full ophthalmologic examination (with a fundoscopy), a spectral domain ocular coherence tomography (SD-OCT) and a mfERG.

RESULTS

A total of 86 subjects were included: 54 SCD patients (107 eyes) with 32 HbSS (63 eyes) and 22 HbSC (44 eyes) and 32 controls (64 eyes). None of the eyes showed retinal clinical abnormalities. SD-OCT analysis showed that macular thickness was statistically lower in SCD eyes than in controls. mfERG analysis demonstrated a significant reduction of N1 (initial-negative deflection), and P1 (positive peak) response amplitude densities of HbSS eyes compared to HbAA eyes from the centre (<2°) and to the periphery (>15°). Implicit time response was also reduced in the centre (<2°). N1 and P1 response amplitude densities of HbSC eyes were significantly lower than those of HbAA eyes from the centre (<2°) to the periphery (>15°). N1 implicit time was statistically reduced in HbSS compared to HbSC eyes.

CONCLUSION

Our study is the first one to describe macular electrophysiological dysfunction in SCD patients. Moreover, we confirm that SCD maculopathy is equally frequent in HbSS and HbSC.

Hemoglobin level and macular thinning in sickle cell disease

Purpose: To study the relationship between complete blood count (CBC) indices over time, particularly serum hemoglobin (Hb) levels, and severity of macular thinning on spectral domain optical coherence tomography (SD-OCT) in patients with sickle cell disease (SCD).

Methods: This is a single-center, retrospective analysis of 141 consecutive SCD patients over a 10-year period, of which 40 patients (79 eyes) had SD-OCT imaging of the macula and 29 (58 eyes, mean age 17.5 years) were eligible for the study. Investigators reviewed electronic medical records for documentation of retinopathy stage, disease genotype, CBC values, and SD-OCT imaging. SD-OCT parameters and CBC values were compared between different retinopathy stages and disease genotypes. Regression analyses were performed on SD-OCT parameters and CBC values.

Results: Of the 58 eligible eyes (34HbSS, 18HbSC, 4HbSβ +thal, 2HbS βthal), 18 had PSR (proliferative sickle retinopathy), 14 had NPSR (nonproliferative sickle retinopathy), and 26 had NSR (no sickle retinopathy). Hb values were higher in SC group compared to SS group. Macular thickness in the temporal inner (Δ=26±33 um, p=0.01) and outer (Δ=21±30 um, p=0.02) subfields was higher in SC compared to SS group. Patients with SD-OCT thinning below the 5th percentile in the temporal outer subfields had lower recorded Hb nadirs (6.0±0.9) compared to those with thickness within the top 95th percentile (9.1±2.3). Regression analysis showed temporal macular thickness to be positively correlated with Hb values in the SS group.

Conclusion: Macular thinning observed on SD-OCT in SCD patients with SS genotype may be related to the level of anemia in this population.

Morphine promotes neovascularizing retinopathy in sickle transgeneic mice

Neovascularizing retinopathy is a significant complication of sickle cell disease (SCD), occurring more frequently in HbSC than HbSS disease. This risk difference is concordant with a divergence of angiogenesis risk, as identified by levels of pro- vs anti-angiogenic factors in the sickle patient's blood. Because our prior studies documented that morphine promotes angiogenesis in both malignancy and wound healing, we tested whether chronic opioid treatment would promote retinopathy in NY1DD sickle transgenic mice. After 10 to 15 months of treatment, sickle mice treated with morphine developed neovascularizing retinopathy to a far greater extent than either of the controls (sickle mice treated with saline and wild-type mice treated identically with morphine). Our dissection of the mechanistic linkage between morphine and retinopathy revealed a complex interplay among morphine engagement with its μ opioid receptor (MOR) on retinal endothelial cells (RECs); morphine-induced production of tumor necrosis factor α and interleukin-6 (IL-6), causing increased expression of both MOR and vascular endothelial growth factor receptor 2 (VEGFR2) on RECs; morphine/MOR engagement transactivating VEGFR2; and convergence of MOR, VEGFR2, and IL-6 activation on JAK/STAT3-dependent REC proliferation and angiogenesis. In the NY1DD mice, the result was increased angiogenesis, seen as neovascularizing retinopathy, similar to the retinal pathology occurring in humans with SCD. Therefore, we conclude that chronic opioid exposure, superimposed on the already angiogenic sickle milieu, might enhance risk for retinopathy. These results provide an additional reason for development and application of opioid alternatives for pain control in SCD.

Knowledge, beliefs and practices regarding sickle cell eye disease of patients at the sickle cell unit, Jamaica

Introduction

Sickle cell disease can result in visually threatening eye disease (proliferative sickle cell retinopathy). This can be prevented with timely eye screening. It is important for patients to understand their role. Our research is to determine the knowledge, beliefs and practices (KBP) regarding eye disease of Sickle Cell patients and the impact of genotype, demographic and socio-economic status.

Methods

Cross-sectional study at the Sickle Cell Unit, Jamaica during May 2016. Consecutive non-pregnant adults (>18 years of age) attendees, who were not acutely unwell, were invited to participate. A 26-item single interviewer administered questionnaire was used to obtain socio-demographic data, highest level of education completed, employment status, sickle cell genotype, if known, frequency of clinic attendance and patients' knowledge, beliefs and practices. Ten of these were yes/no questions, whereas eight required that they choose correct answers from four choices.

Results

One hundred subjects were recruited, 72% had homozygous SS disease. Their ages ranged from 18-63 years (mean 34.1 years, SD11.3). Fifty six percent were female. Most (75%) had achieved at least secondary education. The majority (62%) were unemployed. The mean belief score was 3.6/6(60%) and the mean knowledge and practice scores were 3.3/7(47%) and 2.2/5(44%) respectively. Milder genotypes had higher knowledge scores vs the more severe genotypes (4.0 vs 3.2, P=0.013). Only 28% had regular eye examinations; less than 50% had seen an ophthalmologist in the past year. Practice scores were higher in employed than in unemployed patients (2.6 vs 1.9, (P=0.04)). Employed patients were more likely than the unemployed to see their eye doctor for regular eye “examinations” (42.1% vs 19.4%, χ2=6.0, P=0.02). The practice and knowledge scores correlated (r²=0.363, P<0.001) and belief score (r²=0.304, P =0.002), except where 98% believed they should see an ophthalmologist annually, but only 42% did, and 21% had never.

Conclusion

Knowledge scores were fair, however, the practice was not always in keeping with knowledge.

Gross anterior segment ischaemia following vitreoretinal surgery for sickle-cell retinopathy

We report the case of a 32-year-old Afrocaribbean man with known stage 3 proliferative sickle-cell retinopathy who presented with a mixed picture of tractional and rhegmatogenous macula off detachment. He underwent left primary 25 g vitrectomy with silicone oil, delamination and endolaser photocoagulation under a general anaesthetic. He, however, presented 48 hours postoperatively with gross anterior segment ischaemia. His pain and ocular signs settled over the course of a few days following administration of supplemental oxygen, oral steroids, analgesia and intravenous hydration. Examination showed resolution of his proptosis and orbital signs as well as anterior segment inflammation. He remains under follow-up.

High Healthcare Utilization in Adolescents with Sickle Cell Disease Prior to Transition to Adult Care: A Retrospective Study

BACKGROUND

The transition from pediatric to adult care in the US is often difficult for individuals with sickle cell disease (SCD). Young adults (18 to 25 years of age) have higher acute care utilization and an increased risk of poor outcomes. The current study was designed to provide greater insights into patients (16 to 18 years of age) with SCD prior to their transition to adult care.

OBJECTIVES

To describe current treatment patterns, pain crises prevalence, SCD-related complications, and healthcare resource utilization (HCRU) in 16-to-18-year-old patients with SCD.

METHODS

From 1/1/2015-6/30/2017 using MarketScan Databases, patients were included if they were 16 to 18 years old at the index date, had ≥1 inpatient or 2 outpatient SCD diagnosis claims during the identification period, and were continuously enrolled in the database for at least one year prior (baseline) and post index date. Outcomes included medications, disease management interventions, Charlson Comorbidity Index (CCI), vaso-occlusive (VOC) crises requiring healthcare visits, HCRU, and SCD complications.

RESULTS

1,186 patients were included; most (64.3%) were female. The mean CCI was 1.3 (SD: 0.7). In the overall cohort, patients experienced an average of 3.9 (SD: 4.2) VOCs and most patients (61.1%, n=725) had chronic complications during the one-year follow-up. Pulmonary disease (31.1%, n=369) was the most frequent complication; blood transfusions (mean: 8.4 [SD:7.0]) and iron-chelating therapies (mean: 8.6 [SD:10]) were the most common interventions and medications, respectively. In the 16 to 18 year old group, patients with SCD had 2.0 (SD = 2.3) hospital admissions, 3.4 (SD = 4.0) ER visits, and 5.0 (SD = 4.2) office visits.

CONCLUSIONS

Prior to transition to adult care, adolescents with SCD already have significant a cute and chronic disease-related complications, possibly contributing to frequent healthcare visits. Increased attention to this age group, including improvements in disease modifying therapy, are needed prior to transition to adult care systems to improve outcomes.

Clinical and hematological profile in a newborn cohort with hemoglobin SC

OBJECTIVES

Hemoglobin SC is the second most common variant of sickle-cell disease worldwide, after hemoglobin SS. The objectives of the study were to describe the clinical and laboratory characteristics of hemoglobin SC disease in children from a newborn screening program and treated at a blood center.

METHODOLOGY

This study assessed a cohort of 461 infants born between 01/01/1999 and 12/31/2012 and followed-up until 12/31/2014. Clinical events were expressed as rates for 100 patient-years, with 95% confidence intervals. Kaplan-Meier survival curves were created.

RESULTS

The median age of patients was 9.2 years; 47.5% were female. Mean values of blood tests were: hemoglobin, 10.5g/dL; reticulocytes, 3.4%; white blood cells, 11.24×10⁹/L; platelets, 337.1×10⁹/L; and fetal hemoglobin, 6.3%. Clinical events: acute splenic sequestration in 14.8%, blood transfusion 23.4%, overt stroke in 0.2%. The incidence of painful vaso-occlusive episodes was 51 (48.9-53.4) per 100 patient-years and that of infections, 62.2 episodes (59.8-64.8) per 100 patient-years. Transcranial Doppler ultrasonography (n=71) was normal given the current reference values for SS patients. Hydroxyurea was given to ten children, all of whom improvement of painful crises. Retinopathy was observed in 20.3% of 59 children who underwent ophthalmoscopy. Avascular necrosis was detected in seven of 12 patients evaluated, predominantly in the left femur. Echocardiogram compatible with pulmonary hypertension was recorded in 4.6% of 130 children, with an estimated average systolic pulmonary artery pressure of 33.5mmHg. The mortality rate from all causes was 4.3%.

CONCLUSIONS

Clinical severity is variable in SC hemoglobinopathy. Several children have severe manifestations similar to those with SS disease.

Paramacular temporal atrophy in sickle cell disease occurs early in childhood

Background/aims

Initially reported in a few patients with homozygous sickle cell disease (SCD), atrophic areas of the retina temporal from the macula are now known to be present in about 48% of eyes of adult patients with SS-SCD and in 35% of eyes of adult patients with SC-SCD. The aim of this study is to describe this paramacular atrophy in children affected with SCD.

Methods

In this retrospective series, spectral-domain optical coherence tomography images of 81 children with SCD, acquired with specific patterns including one evaluating the retina temporal to the macula, were reviewed, in order to look for retinal atrophy. Fundus examination status for SCD peripheral retinopathy was also reviewed.

Results

Mean age was 12.0 years (SD: 3.56). The genotype distribution was: 64 HbSS (79%), 10 HbSC (12%) and 7 HbS/β0 thalassaemia (9%). Using a usual fovea-centred programme, retinal atrophy was found in 38% of eyes (52% of children). Using a specific temporal pattern, retinal atrophy was found in 53% of eyes (64% of children), with no significant difference in the prevalence between HbSS and HbSC genotype (p=0.92), and no effect of age (mean 12.3 years (SD=3.61) vs11.9 (3.56), p=0.65). Peripheral retinopathy was found in 11% of children, with a significant relation between the HbSC genotype and the severity of the retinopathy (p=0.003).

Conclusion

Paramacular temporal atrophy occurs early in the course of SCD, which suggests distinct mechanisms from those of peripheral retinopathy.

The past, present and future management of sickle cell retinopathy within an African context

Sickle cell retinopathy is a potentially blinding condition that affects young people in the working age group. This review looks at the past, present and future management of sickle cell retinopathy within an African context. After Sickle cell disease was first reported in 1910, some reports from Africa were pivotal in describing the retinal changes associated with the disease. It soon became obvious that there was a varied clinical picture and clinical course. Several landmark studies were carried out in Jamaica to help elucidate the complexities of the disease and outline appropriate clinical management. In most of the developed world, the clinical management of sickle cell disease has improved with concurrent improvement in outcomes. Currently resource constraints in most Sub-Saharan African countries where there is a high burden of disease means that the management of sickle cell retinopathy is fraught with numerous challenges. Future large scale trials in Africa shall hopefully help to better elucidate the mechanisms behind proliferative sickle retinopathy and help in the development of new and improved therapeutic pathways. The use of technology can help immensely in the screening of patients with sickle cell to detect early proliferative changes and if necessary treat accordingly.

A comparison of 23-gauge and 20-gauge vitrectomy for proliferative sickle cell retinopathy - clinical outcomes and surgical management

AIMS

To report anatomical and functional outcomes in patients with proliferative sickle retinopathy (PSR) who underwent 23-gauge (23G) and 20-gauge (20G) vitrectomy.

METHODS

Retrospective consecutive case series of patients who underwent vitreoretinal intervention for complications of PSR between April 2009 and February 2015. Operations were performed at a tertiary referral centre, Moorfields Eye Hospital. Visual acuity and anatomical success rates were evaluated for PSR complicated by retinal detachment, tractional vitreous haemorrhage and macular hole. Proliferative diabetic retinopathy cases were excluded.

RESULTS

A total of 71 eyes (63 patients) underwent vitreoretinal surgery for PSR complications with 26 months mean follow-up. Primary indications were: tractional retinal detachment (TRD, n = 17), TRD with rhegmatogenous retinal detachment (n = 16), rhegmatogenous retinal detachment (n = 5, macula-on: 1, macula-off: 4), vitreous haemorrhage (n = 19), epiretinal membrane (n = 6), and full thickness macula hole (n = 8). Thirty-nine cases underwent 20G vitrectomy, and 23G surgery was performed in 32 eyes. Mean best corrected visual acuity (BCVA) improved from pre-operative 1.30 LogMAR to final BCVA of 0.74 LogMAR (p < 0.01, paired t-test). 23G vitrectomy yielded slightly better 32 vs. 25 ETDRS-letter improvement compared with 20G vitrectomy (p = 0.60, NS, unpaired t-test). 23G was associated with fewer per-operative complications (23G, 18% vs. 20G,13%). The subset of 38 eyes with retinal detachment demonstrated 79% primary reattachment rate, and a smaller BCVA improvement of 3 lines (p = 0.07, paired t-test).

CONCLUSIONS

Surgical intervention for complicated PSR can preserve and/or improve vision although the degree of visual acuity stabilisation remains guarded in tractional/rhegmatogenous detachments. 23G vitrectomy may give a better functional outcome with lower per-operative complication rates.

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

Purpose

To 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.

Methods

Thirty 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.

Results

Ongoing 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).

Conclusions

Chronic 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.

A physical approach to model occlusions in the retinal microvasculature

Blood occlusions in the retinal microvasculature contribute to the pathology of many disease states within the eye. These events can cause haemorrhaging and retinal detachment, leading to a loss of vision in the affected patient. Here, we present a physical approach to characterising the collective cell dynamics leading to plug formation, through the use of a bespoke microfluidic device, and through the derivation of a probabilistic model. Our microfluidic device is based on a filtration design that can tune the particle volume fraction of a flowing suspension within a conduit, with sizes similar to arterioles. This allows us to control and reproduce an occlusive event. The formation of the occlusion can be examined through the extracted motion of particles within the channel, which enables the assessment of individual and collective particle dynamics in the time leading to the clogging event. In particular, we observe that at the onset of the occlusion, particles form an arch bridging the channel walls. The data presented here inform the development of our mathematical model, which captures the essential factors promoting occlusions, and notably highlights the central role of adhesion in these processes. Both the physical and probabilistic models rely on significant approximations, and future investigation will seek to assess these approximations, including the deformability and complex flow profiles of the blood constituents. However, we anticipate that the general mechanisms of occlusion may be elucidated from these simple models. As microvascular flows in the eye can now be measured in vivo and non-invasively with single cell resolution, our model will also be compared to the pathophysiological characteristics of the human microcirculation.