Sickle cell retinopathy. A focused review

Effect of allogeneic hematopoietic stem cell transplantation on sickle cell disease-related organ complications: A systematic review and meta-analysis

Sickle cell disease (SCD)-related organ complications are a major cause of morbidity and mortality in patients with SCD. We sought to assess whether hematopoietic stem cell transplantation (HSCT) stabilizes, attenuates, or exacerbates organ decline. We performed a systematic review and meta-analysis of trials investigating organ function before and after HSCT in patients with SCD. We searched MEDLINE/PubMed and EMBASE up to September 21, 2023. Continuous data were expressed as standardized mean difference (SMD) and pooled in a weighted inverse-variance random-effects model; binomial data were expressed as risk ratio (RR) using the Mantel-Haenszel random-effects meta-analyses. Of 823 screened studies, 34 were included in this review. Of these, 17 (774 patients, 23.6% adults, 86.3% HLA-identical sibling donor, 56.7% myeloablative conditioning regimen) were included in the meta-analyses. Pulmonary function remained stable. Mean tricuspid regurgitant jet velocity decreased but did not reach statistical significance. In children, estimated glomerular filtration rate decreased (SMD -0.80, p = .01), and the presence of proteinuria increased (RR 2.00, p = <.01), while splenic uptake and phagocytic function improved (RR 0.31, p = <.01; RR 0.23, p = <.01). Cerebral blood flow improved (SMD -1.39, p = <.01), and a low incidence of stroke after transplantation in high-risk patients was found. Retinopathy and avascular osteonecrosis were investigated in only one study, showing no significant changes. While HSCT can improve some SCD-related organ dysfunctions, transplantation-related toxicity may have an adverse effect on others. Future research should focus on identifying individuals with SCD who might benefit most from HSCT and which forms of organ damage are more likely to exacerbate post-transplantation.

Systemic medications for sickle cell disease and potential applications for sickle cell retinopathy

PURPOSE OF REVIEW

To review the literature evaluating systemic medications for treatment of sickle cell disease (SCD) and their applications for sickle cell retinopathy.

RECENT FINDINGS

Prior studies have demonstrated the efficacy of traditional systemic therapies in reducing the risk of development of sickle cell retinopathy. Since 2017, several new and promising disease-modifying therapies for sickle cell disease have been approved for clinical use, including the first genetic therapies such as exagamglogene autotemcel (exa-cel) and lovotibeglogene autotemcel (lovo-cel). These treatments have shown promising results for systemic management but are not widely utilized due to limited access and high cost. The efficacy of these therapies for the prevention of sickle cell retinopathy remains unknown and opens the door to new avenues for research. Furthermore, the role of systemic therapy for the management of hemoglobin SC (HbSC) disease, which has milder systemic effects but higher likelihood of causing retinopathy, remains poorly understood.

SUMMARY

Hydroxyurea has been a mainstay of systemic management of SCD with prior work suggesting its ability to reduce the likelihood of developing retinopathy. There are several new and potentially curative systemic therapies for SCD, though their role in retinopathy prevention and management has not been studied extensively. Future studies are necessary to understand the implications of these emerging therapies for sickle cell retinopathy.

Visual outcome of treating proliferative sickle cell retinopathy in 108 eyes

AIM

To report treatment methods and visual outcome of treating proliferative sickle cell retinopathy (PSCR).

DESIGN

Retrospective interventional.

METHODS

Review of PSCR eyes treated between 2017 to 2022. Patient demographics, fundus findings at presentation, genotype, PSCR stage, treatment used, and visual outcome were assessed.

RESULTS

108 eyes of 88 consecutive patients were studied. Male: Female 48:40. Mean age: 38.91 (SD:12.52) years. Genotype: sickle cell haemoglobin C (SC) 83 eyes (76.9%), sickle cell haemoglobin S (SS) 19 eyes (17.6%), and sickle cell trait (AS) 6 eyes (5.5%). PSCR stages: 3: 15 eyes (11.0%), 4: 74 eyes (67.0%), and 5: 19 eyes (22.0%). Treatment methods: Intravitreal Injection (IVI) of anti-vascular endothelial growth factor (VEGF) only (27 eyes,25%), scatter retinal laser photocoagulation (SRLP) only (7 eyes, 6.5%), Vitrectomy + SRLP (29 eyes, 26.9%), IVI + SRLP (25 eyes, 23.1%), and Vitrectomy + IVI + SRLP (20 eyes, 18.5%). The treatment used correlated with PSCR stage (p = 0.000). IVI only was mostly used to treat stage 4 (81.4%), and SRLP only was used for stages 3 (42.9%) and 5 (57.1%). IVI + SRLP treated eyes had the best pre- and post-treatment vision. Vitrectomy + SRLP treated eyes had the most improved vision. SRLP only had least visual improvement. Fundus findings correlated with visual outcome (p = 0.003); but stage of PSCR, genotype and treatment used had no correlation (P > 0.05).

CONCLUSION

Several options effectively treat PSCR. Visual outcome improved or remained same in 90.7% of treated eyes. Randomized controlled trials will determine the optimum treatment for each distinct presentation of PSCR. Treatment guidelines and a disease classification system of prognostic value are unmet needs.

Proliferative Sickle Cell Retinopathy: Outcomes of Vitreoretinal Surgery

PURPOSE

To report the clinical presentation and outcomes in patients who underwent surgery for proliferative sickle cell retinopathy (PSCR).

DESIGN

Retrospective, consecutive case series.

SUBJECTS

All patients who underwent vitreoretinal surgery for complications secondary to PSCR between January 1, 2014, and December 31, 2021, at a university referral center.

METHODS

Retrospective consecutive case series.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (BCVA), single operation anatomic success rate.

RESULTS

The study included 65 eyes of 61 patients. Disease distribution included 24 (44.4%) eyes with hemoglobin SC disease, 14 (25.9%) with hemoglobin SS disease, 13 (24.1%) with sickle cell trait, and 3 (5.6%) with sickle cell-β thalassemia. Preoperative transfusion was not performed in any study patients. Regional anesthesia with monitored anesthesia care (RA-MAC) was utilized in 58 (89.2%) eyes and general anesthesia in 7 (10.8%). In eyes that underwent surgery for retinal detachment (RD; N = 52) the rate of single operation anatomic success was 72.4% with combined scleral buckling/pars plana vitrectomy (SB/PPV; N = 29) compared with 47.8% with PPV alone (N = 23; P = 0.07). Mean BCVA at the last follow-up examination was 1.27 (20/372) in the SB/PPV group and 1.05 (20/226) in the PPV group (P = 0.48). In all SB cases, an encircling band was utilized and there were no known cases of anterior segment ischemia. All eyes that had surgery for vitreous hemorrhage (N = 13) underwent PPV with endolaser and mean BCVA improved from 1.67 (20/944) preoperatively to 0.45 (20/56) at last follow-up examination (P < 0.001). Mean preoperative BCVA, indication for surgery, single operation success rate, and mean BCVA at last follow-up examination did not differ based on sickle cell disease type (P > 0.05).

CONCLUSIONS

In patients with RD, SB/PPV achieved slightly higher rates of single operation anatomic success compared with PPV alone. Visual acuity outcomes were similar in the 2 groups. The majority of patients received RA-MAC anesthesia and preoperative transfusions were not performed. There were no cases of postoperative anterior segment ischemia. Hemoglobin SC disease was the most common disease type in the current study and surgical outcomes did not differ between sickle cell disease types.

FINANCIAL DISCLOSURE(S)

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

Longitudinal Assessment of Macular Thickness and Microvascular Changes in Children with Sickle Cell Disease

PURPOSE

To longitudinally assess macular thickness and microvascular changes in children with sickle cell disease (SCD).

DESIGN

A retrospective consecutive series.

SUBJECTS

Children with SCD aged ≤ 18 years who had an ophthalmic examination at Boston Children's Hospital between January 1998 and August 2022.

METHODS

Qualitative and quantitative analyses of both OCT and OCT angiography (OCTA) images were performed.

MAIN OUTCOME MEASURES

Total retinal thickness measured on macular OCT, superficial capillary plexus and deep capillary plexus (DCP) vessel density (VD), and foveal avascular zone (FAZ) area measured on 6- × 6-mm OCTA scans.

RESULTS

International Classification of Diseases, 10th Revision, code search identified 303 pediatric SCD patients who underwent ophthalmic examination during the study period. OCT and OCTA images were acquired on 104 (17.2%) and 60 (9.9%) eyes at presentation and on 159 (26.2%) and 100 (16.5%) eyes at final visit, respectively. Overall, temporal retinal thinning was noted qualitatively in 35.6% of SCD patients at presentation and 39.6% at final visit. Of those patients with macular thinning, 94.6% and 90.5% had peripheral sickle cell retinopathy (SCR) at presentation and final visit. On quantitative OCT analysis, HbSS eyes had a lower retinal thickness in the fovea and temporal parafovea compared with HbSC (P < 0.05). Eyes with peripheral SCR had a larger FAZ at presentation compared with eyes without peripheral SCR (P = 0.004), a lower DCP VD at final visit in the inferior temporal macula (P = 0.03), and a higher DCP VD at final visit in the superior nasal macula (P = 0.01). Eighty eyes of 40 patients had OCT, and 34 eyes of 20 patients had both OCT and OCTA images acquired at both initial and final visits. At final visit, retinal thickness decreased at the fovea, inferior perifovea, and temporal perifovea compared with presentation (P < 0.05). In parallel, VD DCP in the superonasal quadrant increased at final visit (P = 0.03).

CONCLUSIONS

Macular retinal thinning was progressive and observed in eyes with and without peripheral SCR. Over time, there was a compensatory increase in DCP VD in the nasal macula on OCTA.

FINANCIAL DISCLOSURE(S)

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

Molecular characterisation of sickle cell disease and classification of major haplotypes associated with the β-globin cluster (HBB gene) by means of SNP marker sequencing in a group of samples from Bolívar, Colombia

BACKGROUND

Colombia has a mestizo population and the prevalence of haemoglobin variants varies according to each region, but heterozygous carriers can be found in all of them.

AIM

To characterise sickle cell disease (SCD) haematologically, biochemically, and molecularly, and detect classic haplotypes by DNA sequencing in a group of samples from Bolívar, Colombia.

SUBJECTS AND METHODS

Blood samples were collected after informed consent from volunteers from eight communities in the Bolívar department, plus samples from the Pacific region, Providencia Island, and Bogotá were included. Data were obtained from: (1) haematological analyses; (2) biochemical tests: dHPLC was used to determine haemoglobin (Hb); and (3) DNA sequencing data through five SNPs.

RESULTS

101 samples were identified by rs334 through Sanger's Sequencing, structural haemoglobinopathies HbAS (34.65%), HbSS (2.97%) and HbAC (1.98%) were found. When contrasting the Hb identification results between SNP rs334 Vs. dHPLC/Isoelectric Focusing (IEF), a coincidence was found in 39/43 samples analysed, therefore, when comparing these techniques, a significant correlation was found (Pearson's correlation coefficient r = 0.998). 26 samples previously analysed by rs334 were classified into classical haplotypes CAR (50.0%), BEN (30.76%), CAM (7.69%), SEN (3.84%), and ATP-I (7.69%).

CONCLUSIONS

SCD characterisation and SNPs-based classification through Sanger's DNA sequencing have not been performed before in Colombia. The results of this work will make it possible to expand the data or records of carriers and those affected, which will benefit patients and their families.

Terminology for Retinal Findings in Sickle Cell Disease Research: A Scoping Review

OBJECTIVE

To review the current sickle cell disease (SCD) literature to assess how "retinopathy" has been defined and to identify ocular outcomes that have been measured and described.

DESIGN

A systematic scoping review of SCD literature was completed regarding ocular manifestations of SCD and vision outcomes across all medical specialties.

SUBJECTS

Participants with SCD and control patients were included in our data extraction.

METHODS

We reviewed English-language literature from 2000 to 2021 for eligible studies by searching PubMed, Google Scholar, Embase, and the Cochrane library using terms to encompass SCD and ocular findings.

MAIN OUTCOME MEASURES

Data collection included study information, patient characteristics, vision-related findings (inclusion criteria and/or study outcomes), and retinopathy characteristics (definition, when, how and by whom diagnosed).

RESULTS

We identified 4006 unique citations and 111 were included in the analysis. Ophthalmologists were senior authors of about half (59/111; 53.2%) of the articles; most articles were published between 2016 and 2021 (71/111; 70.0%). The studies had been conducted primarily in North America (54/111; 48.6%) or Europe (23/111; 20.7%); designs were cross-sectional (51/111; 45.9%), prospective cohort (28/111; 25.2%), retrospective cohort (27/111; 24.3%), and case-control (4/111; 3.6%). Among studies reporting any retinopathy, it was commonly defined as a combination of nonproliferative sickle cell retinopathy and proliferative sickle cell retinopathy (PSR; 52/87; 59.8%), infrequently as PSR only (6/87; 6.9%), or not defined at all (23/87; 26.4%). The Goldberg classification was used to grade retinopathy in almost half of the studies (41/87; 47.1%). Investigators reporting diagnostic methods used clinical fundus examination (56/111; 50.4%), OCT (24/111; 21.6%), fluorescein angiography (20/111; 18.0%), ultrawidefield fundus photographs (15/111; 13.5%), and OCT angiography (10/111; 9.0%), or did not report methods (28/111; 25.2%).

CONCLUSIONS

There are inconsistencies in documentation of methods and outcomes in studies of SCD ophthalmic findings. Particularly concerning is the lack of documentation of ophthalmic examination methods, qualifications of examiners, and clarity and specificity of sickle cell retinopathy definitions. With the increase in SCD treatment research and novel systemic therapies available, it is important to adopt clear and consistent descriptions and rigorous data collection and reporting of ophthalmic outcomes in SCD studies.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.

Acute macular infarctions in pediatric patients with hemoglobin SS disease

Purpose

To report two cases of symptomatic posterior pole arterial occlusions in patients with hemoglobin SS disease.

Observations

Two teenage patients with hemoglobin SS disease presented with visual distortions, and on dilated fundus examination and testing, they were found to have arterial occlusions involving the posterior pole. The patients were evaluated for stroke with head imaging and received exchange transfusion by hematology.

Conclusions and Importance

This case series reports the unusual findings of arterial occlusions in the posterior pole resulting in areas of retinal whitening and ischemia in patients with HbSS. While sickle cell retinopathy is typically considered a peripheral retinal disease, these findings underscore the importance of vigilance when examining patients with sickle cell disease.

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.

Proliferative Sickle Cell Retinopathy in the Retinal Periphery Detected by Ultra-Widefield Imaging: A Case Report

Sickle cell proliferative retinopathy usually presents first in the peripheral retina and the ability to extend and enhance our visualization of the peripheral retina would allow for superior clinical decision-making. In our practice, we had a 28-year-old patient diagnosed with major sickle cell disease of the homozygous type SS (HbSS) that presented with sickle cell proliferative retinopathy detected by ultra-widefield imaging in the nasal side of the left fundus. At follow-up, neovascularization was detected in the extreme nasal periphery of the left eye by ultra-widefield imaging fluorescein angiography with right gaze. The case was graded as Goldberg stage 3, and the patient was administered photocoagulation treatment. With further advancements in the quality and modality of peripheral retinal imaging, novel proliferative lesions can be detected and appropriately managed much earlier than was previously possible. Ultra-widefield imaging allows for the visualization of the central 200 degrees of the retina but, with gaze view, peripheral retina beyond 200 degrees can be reached.

Proliferative Retinopathy Associated with Repeated High-Altitude Exposure in a Patient with Sickle Cell Trait

Broadhead Geoffrey K., Henry E. Wiley, David Peprah, Kenneth Olumba, and Alisa T. Thavikulwat. Proliferative retinopathy associated with repeated high-altitude exposure in a patient with sickle cell trait. High Alt Med Biol. 23:369-371, 2022.-Sickle cell trait (SCT), a carrier state characterized by one normal copy of the beta-globin gene (producing hemoglobin A) and one abnormal variant (producing hemoglobin S), is typically asymptomatic and very low risk for manifestations of hemoglobinopathy, including development of retinopathy. Reported cases of proliferative retinopathy in patients with SCT have occurred in the context of concurrent ocular or systemic disease. We report a case of an otherwise healthy patient with SCT who developed proliferative retinopathy requiring surgical intervention in the setting of significant exposure to high altitude through increased work hours as a flight attendant in the month leading to her presentation. Significant high-altitude exposure may contribute to development of retinopathy in patients with sickle trait. Practitioners should consider the possibility of sickle cell retinopathy in patients with sickle trait in these circumstances.

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.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40942-022-00419-8.

Incidence of eye complications among sickle cell disease patients in Jeddah, Saudi Arabia: A cross-sectional study

Introduction

Sickle cell disease (SCD) is a heritable blood disorder resulting in deformed, rigid red blood cells, rendering them more prone to vaso-occlusion. Ocular complications are known to affect multiple organs through the body's vasculature. Here, we evaluated the incidence of eye complications in patients with SCD at King Abdulaziz Medical City in Jeddah, Saudi Arabia.

Materials and methods

We used a cross-sectional approach and collected relevant medical data from nine patients with SCD. Ophthalmic assessment included visual acuity and an in-clinic dilated fundus examination. All patients were asked to attend the ophthalmology clinic to undergo optical coherence tomography (OCT) angiography, macular OCT scan, and fundus photography. The results of the imaging tests were interpreted by a certified ophthalmology consultant specializing in retinal diseases. Descriptive analyses of the results were also performed.

Results

The mean age of the nine patients was 24.78 ± 10.9 years. All patients were non-hypertensive, one had type 1 diabetes, and another had type 2 diabetes. Five patients had normal visual acuity, two had slight impairments in at least one eye, and two had moderate impairment in at least one eye. One of the nine patients exhibited retinal ischemia in the right eye despite normal macular thickness (visual acuity, OD, 6/30; OS, 6/21). The remaining eight patients showed no ocular abnormalities.

Conclusion

Of the nine patients with SCD, five showed no symptoms of ocular complications. One patient showed retinal ischemia in the right eye, despite a normal macular thickness. This study's results suggest routine ophthalmologic examination may not be able to detect or monitor macular or retinal abnormalities unless augmented with detailed imaging techniques.

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Out of nine patients with SCD, five patients exhibited normal visual acuity.

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One patient presented perifoveal retinal ischemia in the right eye.

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Results suggest augmenting routine ophthalmology screening with imaging techniques.

Sickle Cell Trait Presenting as Unilateral Proliferative Retinopathy and Macular Thinning in a Pregnant Woman

Background

To report a case of a pregnant woman with sickle cell trait (SCT) who presented with unilateral proliferative sickle cell retinopathy. Case Presentation. A 26-year-old otherwise healthy pregnant woman presented with the complaint of visual loss in her left eye. The funduscopic examination showed vitreous hemorrhage, sea fan neovascularization, and pale optic disc. Optical coherence tomography revealed macular inner retinal layer thinning and foveal splaying (saucerization of the foveal pit). The investigations, including hemoglobin electrophoresis, verified the diagnosis of sickle cell trait. Blood pressure, fasting blood glucose tests, and tuberculin skin tests were normal. We treated the patient by peripheral retinal photocoagulation over the area of nonperfusion.

Conclusion

Even though the sickle cell trait is generally considered as a milder form of sickle cell disease without severe retinal manifestations, pregnancy should be considered as a trigger that can induce proliferative changes and foveal splaying in this group of patients.

Homer signaling pathways as effective therapeutic targets for ischemic and traumatic brain injuries and retinal lesions

Ischemic and traumatic insults to the central nervous system account for most serious acute and fatal brain injuries and are usually characterized by primary and secondary damage. Secondary damage presents the greatest challenge for medical staff; however, there are currently few effective therapeutic targets for secondary damage. Homer proteins are postsynaptic scaffolding proteins that have been implicated in ischemic and traumatic insults to the central nervous system. Homer signaling can exert either positive or negative effects during such insults, depending on the specific subtype of Homer protein. Homer 1b/c couples with other proteins to form postsynaptic densities, which form the basis of synaptic transmission, while Homer1a expression can be induced by harmful external factors. Homer 1c is used as a unique biomarker to reveal alterations in synaptic connectivity before and during the early stages of apoptosis in retinal ganglion cells, mediated or affected by extracellular or intracellular signaling or cytoskeletal processes. This review summarizes the structural features, related signaling pathways, and diverse roles of Homer proteins in physiological and pathological processes. Upregulating Homer1a or downregulating Homer1b/c may play a neuroprotective role in secondary brain injuries. Homer also plays an important role in the formation of photoreceptor synapses. These findings confirm the neuroprotective effects of Homer, and support the future design of therapeutic drug targets or gene therapies for ischemic and traumatic brain injuries and retinal disorders based on Homer proteins.

Current and novel multi-imaging modalities to assess retinal oxygenation and blood flow

Retinal ischemia characterizes the underlying pathology in a multitude of retinal diseases that can ultimately lead to vision loss. A variety of novel imaging modalities have been developed to characterize retinal ischemia by measuring retinal oxygenation and blood flow in-vivo. These technologies offer valuable insight into the earliest pathophysiologic changes within the retina and provide physicians and researchers with new diagnostic and monitoring capabilities. Future retinal imaging technologies with the capability to provide affordable, noninvasive, and comprehensive data on oxygen saturation, vasculature, and blood flow mechanics are needed. This review will highlight current and future trends in multimodal imaging to assess retinal blood flow and oxygenation.

Isolated Unilateral Orbital Compression Syndrome in A 19-Year-Old Male With Homozygous Sickle Cell Disease

This study aimed to report a rare case of a rapidly progressive isolated unilateral orbital compression syndrome in a male with homozygous sickle cell disease, who presented with proptosis and optic nerve dysfunction. He neither had long bone pain crisis nor fever at the time of presentation that was managed surgically to preserve vision. Rapidly progressive left orbital swelling is observed in a 19-year-old homozygous sickle cell disease patient associated with severe pain, headache, and impaired vision. Computed tomography of the orbit confirmed the presence of a unilateral large superior sub-periosteal cystic mass. Surgical exploration via anterior orbitotomy revealed a large sub-periosteal hematoma occupying the superior orbit which was evacuated. The patient completely recovered within 14 days post-surgery and regained his vision. Orbital involvement in sickle cell disease is rare, however, it can occur as a sequela of vaso-occlusive crisis and bone marrow infarctions leading to bleeding and sub-periosteal hematomas in the orbit. Prompt diagnosis and management of orbital compression syndrome are crucial to prevent permanent optic nerve damage. Hence, cautious evaluation and close monitoring are important, especially in cases where surgical evacuation is indicated for quick recovery and prevention of visual loss.

Rheological Impact of GBT1118 Cessation in a Sickle Mouse Model

In sickle cell disease (SCD), higher whole blood viscosity is a risk factor for vaso-occlusive crisis, avascular necrosis, and proliferative retinopathy. Blood viscosity is strongly impacted by hemoglobin (Hb) levels and red blood cell (RBC) deformability. Voxelotor is a hemoglobin S (HbS) polymerization inhibitor with anti-sickling properties that increases the Hb affinity for oxygen, thereby reducing HbS polymerization. In clinical trials, voxelotor increased Hb by an average of 1g/dl, creating concern that this rise in Hb could increase viscosity, particularly when the drug was cleared. To investigate this potential rebound hyperviscosity effect, we treated SCD mice with GBT1118, a voxelotor analog, and stopped the treatment to determine the effect on blood viscosity and RBC deformability under a range of oxygen concentrations. GBT1118 treatment increased Hb, improved RBC deformability by increasing the elongation index under normoxic (EImax) and hypoxic conditions (EImin), and decreased the point of sickling (PoS) without increasing blood viscosity. The anti-sickling effects and improvement of RBC deformability balanced the effect of increased Hb such that there was no increase in blood viscosity. Forty-eight hours after ceasing GBT1118, Hb declined from the rise induced by treatment, viscosity did not increase, and EImin remained elevated compared to control animals. Hb and PoS were not different from control animals, suggesting a return to native oxygen affinity and clearance of the drug. RBC deformability did not return to baseline, suggesting some residual rheological improvement. These data suggest that concerns regarding viscosity rise above pre-treatment levels upon sudden cessation of voxelotor are not warranted.

High Systolic Blood Pressure, Anterior Segment Changes and Visual Impairment Independently Predict Sickle Cell Retinopathy

Sickle cell disease is often complicated by retinopathy, which can be proliferative or non proliferative. Proliferative sickle cell retinopathy potentially leads to blindness. There is a paucity of data on sickle cell disease-related retinopathy from Africa, where the disease is most prevalent. We aimed to determine the clinical, ophthalmic, and laboratory predictors of sickle cell retinopathy in an African population. We conducted a cross-sectional study of 262 participants, aged 13 years and above, with sickle cell disease. Demographic and clinical data were collected using a structured questionnaire and standard physical examinations. Vitreo-retinal specialists performed eye examinations on all the participants. Hematological and biochemical assessments were conducted using standard methods. A multivariate stepwise forward logistic regression was performed to determine the predictors of retinopathy. The median age of the participants was 20 years (interquartile range: 17-25 years). Most of the participants had a homozygous Hb S (HBB: c.20A>T) genotype (96.9%), with 3.1% who carried a Hb S/Hb C (HBB: c.19G>A) genotype. The prevalence of non proliferative sickle cell retinopathy was 24.4%. Only 1.9% had proliferative sickle cell retinopathy (PSCR). Elevated systolic blood pressure (BP) [odds ratio (OR): 6.85, 95% confidence interval (95% CI): 1.05-44.45, p = 0.059], moderate visual impairment (OR: 5.2, 95% CI: 1.39-19.63, p = 0.015), and anterior segment changes (OR: 2.21, 95% CI: 1.19-4.13, p = 0.012) were independently predictive of retinopathy. This study provides new insight into predictors of retinopathy in sickle cell disease, with implications on early screening and prevention.

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.

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.

[Maculopathy in sickle cell disease]

Hintergrund

Die Sichelzellerkrankung (SZE) ist eine hereditäre Hämoglobinopathie, die durch rezidivierende vasookklusive Episoden zur Mikrozirkulationsstörung verschiedener Organsysteme mit teils letalem Ausgang führt. Bei der okulären Manifestation der SZE ist am bekanntesten die periphere Sichelzellretinopathie (SZR). Unabhängig davon kann es bereits früh im Krankheitsverlauf zur Sichelzellmakulopathie (SZM) kommen.

Methoden

Review der internationalen und deutschsprachigen Literatur zur okulären Beteiligung bei SZE mit Fokus auf die SZR und SZM sowie Überblick über aktuelle systemische Therapieansätze bei SZE anlässlich der Vorstellung zweier Patienten mit HbSS-SZE.

Ergebnis und Schlussfolgerung

Im Gegensatz zur SZR ist die SZM mit temporaler Verdünnung der inneren Netzhautschichten erst in den letzten 5 Jahren mit der Einführung von SD-OCT und OCTA vermehrt in die Literatur eingegangen. Unabhängig vom Vorliegen einer SZR kann es immerhin bei etwa der Hälfte der Patienten bereits früh im Krankheitsverlauf zu einer SZM kommen. Das Krankheitsbild wird auch in Deutschland durch den Fortschritt der systemischen Therapiemöglichkeiten und aufgrund von Migration präsenter werden. Durch Wissen um diese Komplikation der SZE kann eine frühzeitige Diagnosestellung erfolgen und unnötige Diagnostik vermieden werden.

Hyperbaric oxygen treatment of central retinal vein occlusion with cilioretinal artery occlusion secondary to hormonal treatment: Case report and review

INTRODUCTION

This report describes a case of central retinal vein occlusion (CRVO) and cilioretinal artery occlusion (CLRAO) after hormonal treatment for induction of ovulation that was successfully treated with hyperbaric oxygen.

CASE REPORT

A 48 year-old woman was admitted to our department for sudden blurred vision in her left eye. The patient had a history of 3-months hormonal treatment for induction of ovulation. The best corrected visual acuity was 7/10 (20/32) in the left eye and 10/10 (20/20) in the right eye. Fundus examination of the left eye revealed flame-shaped haemorrhages, whitening of the retina along the distribution of cilioretinal artery and tortuous retinal veins. Fluorescein angiography confirmed the combination of a non-ischaemic CRVO with CLRAO. The patient was treated with a 2 h session of hyperbaric oxygen at 253 kPa (2.5 atmospheres absolute) once daily for a total of 30 sessions. Best corrected visual acuity improved to 10/10 (20/20) in the left eye.

CONCLUSIONS

CRVO and CLRAO are both occlusive disorders. HBOT is a safe low-cost treatment modality that can be beneficial in some ocular pathologies. It can maintain oxygenation of the retina through the choroidal blood supply, decrease oedema and preserve compromised tissue adjacent to the ischaemic area.

Cell-derived microparticles and sickle cell disease chronic vasculopathy in sub-Saharan Africa: A multinational study

Although most individuals with sickle cell disease (SCD) live in sub-Saharan Africa, the natural history of the disease on this continent remains largely unknown. Intravascular haemolysis results in activation of circulating blood cells and release of microparticles (MPs) that exert pro-inflammatory effects and contribute to vascular damage. We designed a case-control study nested in the CADRE cohort (Coeur-Artère-DRÉpanocytose, clinical trials.gov identifier NCTO3114137) and based on extreme phenotypes, to analyse blood cell-derived MPs in 232 adult SS patients at steady state in Bamako and Dakar. Thirty-six healthy adult controls matched by age and sex were recruited in Bamako. The MPs concentrations were higher in SS patients compared to AA controls with a predominance of erythrocyte- and reticulocyte-derived MPs. These erythroid-derived MPs were significantly lower in patients with retinopathy (P = 0·022). Reticulocyte-derived MPs were significantly negatively and positively associated with a history of priapism (P = 0·020) and leg ulcers (P = 0·041) respectively. We describe for the first time the comparative patterns of plasma MPs in healthy subjects and patients with SCD living in sub-Saharan Africa and exhibiting various complications. Because our present results show no clear pattern of correlation between erythroid MPs and the classical hyper-haemolytic complications, we hypothesise a weak relevance of the hyper-haemolysis versus hyper-viscous paradigm in Africa.

Longitudinal assessment of quantitative ultra-widefield ischaemic and vascular parameters in sickle cell retinopathy

PURPOSE

To evaluate longitudinal quantitative ischaemic and vasculature parameters, including ischaemic index, vessel area, length and geodesic distance in sickle cell retinopathy (SCR) on ultra-widefield fluorescein angiography (UWFA).

METHODS

Optimal UWFA images from two longitudinal timepoints of 74 eyes from 45 patients with SCR were aligned and a common region of interest was determined. A deep-learning augmented ischaemia and vascular segmentation platform was used for feature extraction. Geodesic distance maps demonstrating the shortest distance within the vascular masks from the centre of the optic disc were created. Ischaemic index, vessel area, vessel length and geodesic distance were measured. Paired t-test and linear mixed effect model analysis were performed.

RESULTS

Overall, 25 (44 eyes) patients with HbSS, 14 (19 eyes) with HbSC, 6 (11 eyes) with HbSthal and other genotypes were included. Mean age was 40.1±11.0 years. Mean time interval between two UWFA studies was 23.0±15.1 months (range: 3-71.3). Mean panretinal ischaemic index increased from 10.0±7.2% to 10.9±7.3% (p<0.005). Mean rate of change in ischaemic index was 0.5±0.7% per year. Mean vessel area (p=0.020) and geodesic distance (p=0.048) decreased significantly. Multivariate analysis demonstrated baseline ischaemic index and Goldberg stage are correlated with progression.

CONCLUSION

Longitudinal ischaemic index and retinal vascular parameter measurements demonstrate statistically significant progression in SCR. The clinical significance of these relatively small magnitude changes remains unclear but may provide insights into the progression of retinal ischaemia in SCR.

[Sickle cell retinopathy in children: Report of 42 cases]

We aimed to describe the epidemiological, etiological and clinical features, treatment and clinical course of sickle cell retinopathy in children and to determine the risk factors for serious involvement.

METHODS

This was a retrospective study including all children diagnosed with sickle cell retinopathy. Epidemiological, clinical and therapeutic characteristics, as well as clinical course, were analysed retrospectively by chart review. Two groups were defined: Group 1 (Goldberg stage 1 and 2); Group 2 (Goldberg stage 3, 4 and 5). In order to identify factors independently associated with severe sickle cell retinopathy, we conducted a logistic regression analysis in descending order.

RESULTS

The frequency of sickle cell retinopathy was 14.48%. Forty-two patients (84 eyes) were included; among them 23 boys and 19 girls, aged 10 to 17 with a mean age of 14±1.98 years. Twenty patients were of genotype SS, 11 patients of genotype SC, 8 Sβ and 3 SO Arab. The three patients in group 2 were all of SS genotype. The majority of patients (32) had an HbF level of less than 15%. All our patients had sickle cell retinopathy distributed as follows: 62% at stage 1; 31% at stage 2; 5% at stage 3 and 2% at stage 4. Multivariate analysis revealed a single risk factor independently linked to severe involvement - an HbF level<15%.

CONCLUSION

Retinopathy is a frequent complication of sickle cell disease which may lead to blindness. The HbF level is negatively correlated with severe involvement.

Comparison of line-field confocal optical coherence tomography images with histological sections: Validation of a new method for in vivo and non-invasive quantification of superficial dermis thickness

BACKGROUND

Line-field confocal optical coherence tomography (LC-OCT) is an imaging technique providing "optical biopsies" of the skin in real time and non-invasively. At a center optical wavelength of 1.3 µm, this innovative technology can be applied to dermo-cosmetic product development due to both high image resolution (~2 µm) and sufficient penetration (~0.5 mm). Nevertheless, the precise dermal area analyzed with LC-OCT has never been identified. In this study, the objective was to compare LC-OCT images with histological sections of the same area, in order to validate a new method for in vivo and non-invasive quantification of superficial dermis thickness. Once validated, this standardized and quantitative method was used to assess age-related changes of the superficial dermis.

MATERIALS AND METHODS

Ex vivo LC-OCT acquisitions and hematoxylin-eosin-safran staining were performed on a panel of four healthy Caucasian female volunteers. In vivo LC-OCT study of skin aging was performed on a panel of 37 healthy Caucasian female divided into five different age-groups.

RESULTS

Comparison with histological sections revealed that LC-OCT images allow the visualization and the quantification of the superficial portion of papillary dermis. Applied to different age-group of volunteers, LC-OCT images show a constant decrease in this superficial dermis thickness with age.

CONCLUSIONS

In conclusion, we have introduced LC-OCT as a novel technique for in vivo and non-invasive evaluation of superficial dermis thickness. This approach could be used in the future to demonstrate visually and quantitatively the capacity of a dermo-cosmetic active ingredient to renormalize the structural properties of the dermis.