Structural and functional correlation in sickle cell retinopathy using spectral-domain optical coherence tomography and scanning laser ophthalmoscope microperimetry

Proliferative Sickle Cell Retinopathy: A Patient and a Physician's Perspective on Quality of Life and Quality of Eye Care

The impact of visual impairment in the context of sickle cell disease is poorly understood. Despite the significant advancements over the past three decades in retinal imaging and in the understanding of molecular mechanisms that drive retinal neovascularization, there has been little improvement in the management of proliferative sickle cell retinopathy. This article is co-authored by a patient impacted by proliferative sickle cell retinopathy. She highlights her personal experience of sight loss from proliferative sickle cell retinopathy and the impact on her daily life and mental health. Subsequent to diagnosis and management of proliferative sickle cell retinopathy, she continues to live with irreversible sight loss and provides crucial insight from a patient's perspective into the broad lack of high-quality educational materials online and lack of understanding of the disease within the clinical community. This article aims to provide a strong narrative to emphasize the need for further qualitative and quantitative research in this area, to bring about the holistic step-change required to improve visual outcomes and eyecare for people with sickle cell disease.

ATYPICAL FOVEAL AND PARAFOVEAL ABNORMALITIES IN SICKLE CELL DISEASE

PURPOSE

The primary aim was to describe the patterns of paramacular involvement, not yet reported but that optical coherence tomography angiography can now detect in patients with sickle cell disease. The secondary aim was to search arguments concerning the physiopathogeny of paramacular involvement.

METHODS

This institutional cohort retrospective study was conducted in a Referral Center for Ophthalmological Rare Diseases. Follow-up included an ophthalmologic examination with optical coherent tomography and optical coherent tomography angiography.

RESULTS

One hundred and thirty-two patients with SCD were included. Typical sickle cell maculopathy was observed in temporal area in 84 eyes (40.0%) of SS patients and eight eyes (14.8%) of SC patients ( P < 0.001). Enlargement of the foveal avascular zone was observed in 10 eyes of eight SS patients. Two atypical parafoveal abnormalities were found in SS patients only. The first one consisted of macular thinning with normal vascularization in 15 eyes of 11 patients. The second atypical maculopathy was large areas of loss of vascularization without retinal thinning 10 eyes of six patients. Multivariate analysis did not show a statistically significant relation between the peripheral sickle retinopathy stage and the different type of sickle cell maculopathy ( P = 0.21).

CONCLUSION

Those atypical sickle cell maculopathy may correspond to early forms preceding a typical sickle cell disease maculopathy (SCDM). This would point toward several physiopathogenic mechanisms. The first one included the existence of ischemia that can be related to anemia. Presence of retinal thinning without vascular involvement point out to a neurogenic mechanism.

Sickle Eye Project: a cross-sectional, non-interventional study of the prevalence of visual impairment due to sickle cell retinopathy and maculopathy in the UK

INTRODUCTION

Sickle cell disease (SCD) is one of the most common genetic disorders in the UK, with over 15 000 people affected. Proliferative sickle cell retinopathy (SCR) is a well-described complication of SCD and can result in significant sight loss, although the prevalence in the UK is not currently known. There are currently no national screening guidelines for SCR, with wide variations in the management of the condition across the UK.

METHODS AND ANALYSIS

The Sickle Eye Project is an epidemiological, cross-sectional, non-interventional study to determine the prevalence of visual impairment due to SCR and/or maculopathy in the UK. Haematologists in at least 16 geographically dispersed hospitals in the UK linked to participating eye clinics will offer study participation to consecutive patients meeting the inclusion criteria attending the sickle cell clinic. The following study procedures will be performed: (a) best corrected visual acuity with habitual correction and pinhole, (b) dilated slit lamp biomicroscopy and funduscopy, (c) optical coherence tomography (OCT), (d) OCT angiography where available, (e) ultrawide fundus photography, (f) National Eye Institute Visual Function Questionnaire-25 and (g) acceptability of retinal screening questionnaire. The primary outcome is the proportion of people with SCD with visual impairment defined as logarithm of the minimum angle of resolution ≥0.3 in at least one eye. Secondary outcomes include the prevalence of each stage of SCR and presence of maculopathy by age and genotype; correlation of stage of SCR and maculopathy to severity of SCD; the impact of SCR and presence of maculopathy on vision-related quality of life; and the acceptability to patients of routine retinal imaging for SCR and maculopathy.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the South Central-Oxford A Research Ethics Committee (REC 23/SC/0363). Findings will be reported through academic journals in ophthalmology and haematology.

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.

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.

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.

Artificial intelligence for improving sickle cell retinopathy diagnosis and management

Sickle cell retinopathy is often initially asymptomatic even in proliferative stages, but can progress to cause vision loss due to vitreous haemorrhages or tractional retinal detachments. Challenges with access and adherence to screening dilated fundus examinations, particularly in medically underserved areas where the burden of sickle cell disease is highest, highlight the need for novel approaches to screening for patients with vision-threatening sickle cell retinopathy. This article reviews the existing literature on and suggests future research directions for coupling artificial intelligence with multimodal retinal imaging to expand access to automated, accurate, imaging-based screening for sickle cell retinopathy. Given the variability in retinal specialist practice patterns with regards to monitoring and treatment of sickle cell retinopathy, we also discuss recent progress toward development of machine learning models that can quantitatively track disease progression over time. These artificial intelligence-based applications have great potential for informing evidence-based and resource-efficient clinical diagnosis and management of sickle cell retinopathy.

Monitoring retinal pathology and cerebral injury in sickle cell disease using spectral-domain optical coherence tomography in pediatric patients

PURPOSE

This study aimed to confirm the correlation between sickle cell disease (SCD) genotype and retinal damage identified by spectral-domain optical coherence tomography (SD-OCT), and examine a potential link between hypoxic ischemic injury in the retina and brain.

METHODS

In this prospective, observational case series, 117 patients (56 males) aged 5-20 years with SCD (36 SC, 68 SS, eight Sβ+ thalassemia, five Sβ0 thalassemia) underwent ophthalmologic examination including funduscopy and SD-OCT imaging. Comparison of SCD genotypes and association between ocular findings and cerebrovascular disease (CVD) in subjects with SS/Sβ0 genotype were investigated.

RESULTS

Visual acuity ranged from 20/20 to 20/40. On funduscopic exam, 16 of 117 (13.7%) had retinopathy; 69 of 117 (59.0%) showed inner retina thinning on SD-OCT. Patients with SS/Sβ0 showed a higher frequency of sickle cell retinopathy (SCR) change (68.5% vs. 47.2%), bilateral SCR (49.9% vs. 25.0%), and foveal involvement (15.1% vs. 0) than the SC genotype. While funduscopic findings in our cohort with SS/Sβ0 genotype showed no correlation with CVD, 20 of 21 patients with CVD had abnormal SD-OCT. Elevated reticulocyte percentage and aspartate aminotransferase are associated with SD-OCT changes and CVD.

CONCLUSIONS

SD-OCT was better than funduscopy in detecting retinal changes, higher frequency, and more extensive retinal changes in the more severe SCD genotypes SS and Sβ0 as compared with SC. The correlation between abnormal SD-OCT and CVD strongly suggests that retinal exam using SD-OCT may aid in detection and monitoring SCD-related CVD. Retinopathy may be another component of the hemolytic subphenotype of SCD.

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.

Longitudinal Assessment of Retinal Thinning in Adults With and Without Sickle Cell Retinopathy Using Spectral-Domain Optical Coherence Tomography

Importance

Determination of retinal thinning rates may help to identify patients who are at risk of progression of sickle cell retinopathy.

Objective

To assess the rates of macular thinning in adults with and without sickle cell retinopathy using spectral-domain optical coherence tomography (OCT) and to identify ocular and systemic risk factors associated with retinal thinning.

Design, Setting, and Participants

This longitudinal prospective case-control study enrolled adult participants from a university-based retina subspecialty clinic between February 11, 2009, and July 3, 2019. The study was designed in autumn 2008 and conducted from February 2, 2009, to July 3, 2020. Participants with sickle cell retinopathy (sickle cell group) were matched by age and race with participants without sickle cell retinopathy (control group). Participants received annual spectral-domain OCT and clinical examinations. Those with at least 1 year of follow-up by July 3, 2020, were included in the analysis. Data were analyzed from February 2, 2009, to July 3, 2020.

Main Outcomes and Measures

The primary outcome was comparison of spectral-domain OCT measurements from early-treatment diabetic retinopathy study subfield rates of retinal thinning between eyes with and without sickle cell retinopathy and between different sickle cell hemoglobin subtypes. The secondary outcome was identification of ocular and systemic risk factors associated with rates of retinal thinning.

Results

Among 370 adults (711 eyes) enrolled in the study, 310 participants (606 eyes) had sickle cell retinopathy, and 60 participants (105 eyes) did not. Of those, 175 of 310 participants (56.5%; 344 of 606 eyes [56.8%]; mean [SD] age, 37.8 [12.8] years; 126 women [72.0%]) in the sickle cell group and 31 of 60 participants (51.7%; 46 of 105 eyes [43.8%]; mean [SD] age, 59 [15.4] years; 22 women [71.0%]) in the control group had at least 1 year of clinical and spectral-domain OCT follow-up data from baseline. The mean (SD) follow-up was 53.7 (32.6) months for the sickle cell group and 54.6 (34.9) months for the control group. Rates of macular thinning in the sickle cell group were significantly higher than those in the control group for the inner nasal (difference, -1.18 μm per year; 95% CI, -1.71 to -0.65 μm per year), inner superior (difference, -1.03 μm per year; 95% CI, -1.78 to -0.29 μm per year), inner temporal (difference, -0.61 μm per year; 95% CI, -1.16 to -0.07 μm per year), and outer nasal (difference, -0.41 μm per year; 95% CI, -0.80 to -0.03 μm per year) quadrants. Patients with sickle cell hemoglobin SC and sickle cell hemoglobin β-thalassemia subtypes had higher rates of retinal thinning than those with the sickle cell hemoglobin SS subtype. Risk factors associated with greater rates of retinal thinning included participant age, stage of retinopathy, previous stroke, and presence of hypertension, acute chest syndrome, or diabetes. Hydroxyurea therapy was associated with decreased rates of retinal thinning and may be a protective factor.

Conclusions and Relevance

In this study, rates of retinal thinning were higher among participants with sickle cell retinopathy compared with those without sickle cell retinopathy, and thinning rates increased with participant age and stage of retinopathy. These findings suggest that identifying anatomic worsening of sickle cell maculopathy through spectral-domain OCT may be a useful parameter to evaluate the progression of sickle cell retinopathy.

Central macular thickness in patients with sickle cell disease and no signs of retinopathy: a cross-sectional study of Jordanian patients

OBJECTIVES

To measure central macular thickness in Jordanian patients with sickle cell disease who did not have retinopathy and compare the findings with age- and sex-matched controls using spectral domain optical coherence tomography (SDOCT).

METHODS

In this cross-sectional study, participants underwent visual acuity testing, slit-lamp bio-microscopy, dilated ophthalmoscopy, and SDOCT imaging to measure central macular thickness. Macular quadrant measurements and thickness difference indexes (TDIs) were compared between groups.

RESULTS

Twenty eyes with sickle cell disease and 20 control eyes were enrolled. The median visual acuity in both groups was 20/20. The mean macular thickness was significantly lower in eyes with sickle cell disease than in matched controls (mean difference, 22.15 ± 6.44 µm). Peripheral quadrants were all significantly thinner in eyes with sickle cell disease, especially in superior and temporal quadrants. TDIs were lower in eyes with sickle cell disease than in control eyes.

CONCLUSIONS

Eyes with sickle cell disease that had no clinical evidence of retinopathy exhibited significantly lower central macular thickness in all quadrants, compared with eyes in age- and sex-matched controls. SDOCT is a non-invasive imaging modality that can detect preclinical changes in eyes with sickle cell disease and can be used to screen and monitor the disease process.

Quantification of intermittent retinal capillary perfusion in sickle cell disease

Pathophysiology of sickle cell disease (SCD) features intermittent vaso-occlusion of microcirculatory networks that facilitate ischemic damage. Past research has, however, relied on static images to characterize this active disease state. This study develops imaging metrics to more fully capture dynamic vascular changes, quantifying intermittent retinal capillary perfusion in unaffected controls and SCD patients using sequential optical coherence tomography angiography (OCT-A) scans. The results reveal significant dynamic variation of capillary perfusion in SCD patients compared to controls. This measurement of vaso-occlusive burden in patients would provide utility in monitoring of the disease state and in evaluating treatment efficacy.

Quantifying Areas of Vascular Leakage in Sickle Cell Retinopathy Using Standard and Widefield Fluorescein Angiography

BACKGROUND AND OBJECTIVE

To evaluate neovascular surface area change in sickle cell retinopathy following scatter photocoagulation treatment in wide- and standard-field fluorescein angiography (FA) scans using ImageJ software.

PATIENTS AND METHODS

Images of 11 patients with wide- or standard-field FA scans pre- and post-treatment for sickle cell retinopathy were evaluated retrospectively by two graders using ImageJ. Graders traced lesions in the late arteriovenous phase and calculated the lesion area and intensity relative to the optic disc. Changes in area and intensity pre- to post-treatment were assessed using dependent t-tests.

RESULTS

Pre- to post-treatment, lesion area decreased by 3.34 ± 2.43 to 3.66 ± 3.72 disc areas (P < .001), whereas intensity decreased by 11.36 ± 25.87 to 22.97 ± 69.25 units (P = .104). Neovascular area declined status post-aphotocoagulation by 3.83 ± 3.65 disc areas (P = .003) for widefield images and by 2.81 ± 3.55 discs areas (P = .034) for standard fluorescein images. No statistical difference in area reduction was appreciated between imaging modalities (P = .652) CONCLUSION: Neovascular area decreased significantly following scatter photocoagulation in both standard-field and widefield FA scans without an appreciable difference between imaging modalities. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:153-158.].

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.

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.

UTILITY OF ULTRA-WIDEFIELD RETINAL IMAGING FOR THE STAGING AND MANAGEMENT OF SICKLE CELL RETINOPATHY

PURPOSE

To determine whether ultra-widefield (UWF) retinal imaging changes the staging or management of sickle cell retinopathy compared with clinical examination.

METHODS

Prospective, observational study including patients with sickle cell disease. All patients underwent dilated fundus examination by a fellowship-trained retina specialist, as well as UWF fundus photography (FF) and fluorescein angiography (FA). Sickle retinopathy stage and treatment recommendation per eye were determined after clinical examination, UWF-FF, and UWF-FA, respectively, and differences in retinopathy stage and treatment recommendation were compared.

RESULTS

A total of 70 eyes from 35 patients (17 women, 48.6%), mean age 30.4 years, were included. Sickle genotypes included 26 patients with sickle SS (74.3%), 7 SC (20.0%), and 2 β(+)thalassemia (5.7%). Based on examination, most eyes (42/70; 60.0%) had no visible retinopathy. Based on UWF-FF, about half of the eyes were found to be Goldberg Stage 2 or above (36/70; 51.4%). Based on UWF-FA, nearly all eyes were Goldberg Stage 2 or above (63/70; 90%). However, clinical examination reliably detected neovascularization, and in no case did the addition of UWF imaging change management relative to examination alone.

CONCLUSION

Ultra-widefield imaging detects a higher stage of sickle cell retinopathy compared with clinical examination alone, but these differences may not be clinically significant.

Optical coherence tomography (OCT) and OCT angiography allow early identification of sickle cell maculopathy in children and correlate it with systemic risk factors

PURPOSE

To determine the presence of sickle cell retinopathy and maculopathy and to identify associations between markers of hemolysis and systemic and ocular manifestations in children affected by sickle cell disease.

METHODS

Eighteen children with sickle cell disease, aged 5-16 years, underwent complete eye examination including best-corrected visual acuity, slit-lamp biomicroscopy, ophthalmoscopy after pharmacological mydriasis, spectral-domain optical coherence tomography (SD-OCT), and optical coherence tomography angiography (OCTA). Blood test results and clinical history information were collected for each child, including fetal hemoglobin (HbF), hemoglobin (Hb), hematocrit (Htc), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), reticulocytes percentage (%ret), lactic dehydrogenase (LDH), total and direct bilirubin, glomerular filtration rate, number of painful crises, acute chest syndromes, and splenic sequestration. Therapeutic regimen and transfusion therapy were also evaluated.

RESULTS

Sixteen of 36 eyes (44.4%) had non-proliferative sickle cell retinopathy on ophthalmoscopic evaluation. No patients had proliferative sickle cell retinopathy. In 13 of 36 eyes (36.1%), SD-OCT and OCTA detected signs of sickle cell maculopathy. Nine eyes (25%) presented sickle cell retinopathy and maculopathy, 7 eyes (19.4%) sickle cell retinopathy alone, and 4 eyes (11.1%) sickle cell maculopathy alone. A statistically significant association was found between sickle cell retinopathy; lower levels of HbF, Hb, and Htc; and higher MCV and percentage of reticulocytes. Sickle cell maculopathy was associated with lower values of H and Htc and higher levels of reticulocytes and total bilirubin.

CONCLUSIONS

We identified early signs of sickle cell retinopathy and maculopathy in a pediatric population with SD-OCT and OCTA. These two retinal complications were more frequent in children with higher hemolytic rates.

TEMPORAL THINNING IN SICKLE CELL RETINOPATHY IS ASSOCIATED WITH DIMINISHED PERFUSION ON OCTA AND DENSE SCOTOMA ON MICROPERIMETERY

PURPOSE

To establish correlation between the structural compromise (capillary loss and hypoperfusion on optical coherence tomography [optical coherence tomography angiography]) with perimacular functional impairment noted on microperimetry.

METHODS

Retrospective case series. Clinical records and multimodal imaging findings of patients presenting with sickle cell disease were reviewed.

RESULTS

Three eyes of three patients (two men) were included in the study with a visual acuity of 20/20 and no sickle cell retinopathy. Images using optical coherence tomography angiography (AngioVue OCT angiography system; Optovue, Inc, Fremont, CA) were obtained along with spectral domain optical coherence tomography, fluorescein angiography, and microperimetry (MP-1). Spectral domain optical coherence tomography revealed selective loss of inner retinal layers with thinning of the retina. Optical coherence tomography angiography revealed compromise of both superficial and deep capillaries in the area of temporal thinning expressed on spectral domain optical coherence tomography. MP-1 demonstrated focal increase in threshold (decreased sensitivity) correlating with the perfusion defects on optical coherence tomography angiography. Fluorescein angiography did not show any substantial perfusion compromise.

CONCLUSION

Optical coherence tomography angiography may reflect the extent of functional compromise even before it being evident on fluorescein angiography. The area vascular compromise was larger in the deep plexus compared with the superficial plexus. The area of complete loss of retinal sensitivity corresponds to loss of vasculature in both the superficial and deep plexuses, whereas the area of decreased sensitivities corresponds to compromise only in the deep plexus.

Evaluation of Ocular Complications by Using Optical Coherence Tomography in Children With Sickle Cell Disease Eye Findings in Children With Sickle Cell Disease

OBJECTIVE

The aim of this study was to compare optical coherence tomography (OCT) findings in pediatric patients with sickle cell disease (SCD) and healthy individuals and to investigate associations between these data and the patients' systemic findings.

MATERIALS AND METHODS

The study included 108 eyes of 54 patients with SCD with no visual symptoms and a control group consisting of 110 eyes of 55 healthy subjects with no systemic or ocular pathology. After best-corrected visual acuity assessment, the study participants underwent a complete ophthalmologic examination including intraocular pressure. After examination and pupil dilation induced with 1% tropicamide, 9×9 mm macular sections were obtained with spectral-domain OCT. The macular sections were evaluated according to Early Treatment Diabetic Retinopathy Study (ETDRS) map and internal and external retinal thicknesses were measured using the software included in the OCT device.

RESULTS

The patient group showed significantly more foveal flattening, temporal thinning, and vascular tortuosity than the control group (P<0.0001 for all). Foveal width was significantly greater in the patient group (1592.39±175.56 µm) compared with the control group (1391.01±175.56 µm) (P<0.0001), whereas foveal depth was significantly lower in the patient group (121.15±26.83 µm) than in the control group (146.1±12.25 µm) (P<0.0001). The mean total retinal thickness was 253.53±22.31 µm in the patient group and 261.03±18.48 µm in the control group (P=0.007). Similarly, central retinal thickness was significantly lower in the patient group (219.35±10.53 µm) compared with the control group (235.32±12.51 µm) (P<0.0001).

DISCUSSION

Our study shows that pediatric patients with SCD may have subclinical retinal involvement and that temporal thinning, in particular, is an important OCT finding. This strongly suggests that OCT imaging would be a beneficial addition to routine ophthalmologic examination in the diagnosis and follow-up of this patient group.

Wide-field imaging of sickle retinopathy

Background

Wide-field imaging is a newer retinal imaging technology, capturing up to 200 degrees of the retina in a single photograph. Individuals with sickle cell retinopathy commonly exhibit peripheral retinal ischemia. Patients with proliferative sickle cell retinopathy develop pathologic retinal neovascularization of the peripheral retina which may progress into sight-threatening sequelae of vitreous hemorrhage and/or retinal detachment. The purpose of this review is to provide an overview of current and future applications of wide-field retinal imaging for sickle cell retinopathy, and recommend indications for best use.

Main body

There are several advantages to wide-field imaging in the clinical management of sickle cell disease patients. Retrospective and prospective studies support the success of wide-field imaging in detecting more sickle cell induced retinal microvascular abnormalities than traditional non-wide-field imaging. Clinicians can easily capture a greater extent of the retinal periphery in a patient's clinical baseline imaging to follow the changes at an earlier point and determine the rate of progression over time. Wide-field imaging minimizes patient and photographer burden, necessitating less photos and technical skill to capture the peripheral retina. Minimizing the number of necessary images can be especially helpful for pediatric patients with sickle cell retinopathy. Wide-field imaging has already been successful in identifying new biomarkers and risk factors for the development of proliferative sickle cell retinopathy. While these advantages should be considered, clinicians need to perform a careful risk-benefit analysis before ordering this test. Although wide-field fluorescein angiography successfully detects additional pathologic abnormalities compared to traditional imaging, a recent research study suggests that peripheral changes differentially detected by wide-field imaging may not change clinical management for most sickle cell patients.

Conclusions

While wide-field imaging may not carry a clinically significant direct benefit to all patients, it shows future promise in expanding our knowledge of sickle cell retinopathy. Clinicians may monitor peripheral retinal pathology such as retinal ischemia and retinal neovascularization over progressive time points, and use sequential wide-field retinal images to monitor response to treatment. Future applications for wide-field imaging may include providing data to facilitate machine learning, and potential use in tele-ophthalmology screening for proliferative sickle retinopathy.

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.

Sickle cell retinopathy. A focused review

PURPOSE

To provide a focused review of sickle cell retinopathy in the light of recent advances in the pathogenesis, multimodal retinal imaging, management of the condition, and migration trends, which may lead to increased prevalence of the condition in the Western world.

METHODS

Non-systematic focused literature review.

RESULTS

Sickle retinopathy results from aggregation of abnormal hemoglobin in the red blood cells in the retinal microcirculation, leading to reduced deformability of the red blood cells, stagnant blood flow in the retinal precapillary arterioles, thrombosis, and ischemia. This may be precipitated by hypoxia, acidosis, and hyperosmolarity. Sickle retinopathy may result in sight threatening complications, such as paracentral middle maculopathy or sequelae of proliferative retinopathy, such as vitreous hemorrhage and retinal detachment. New imaging modalities, such as wide-field imaging and optical coherence tomography angiography, have revealed the microstructural features of sickle retinopathy, enabling earlier diagnosis. The vascular growth factor ANGPTL-4 has recently been identified as a potential mediator of progression to proliferative retinopathy and may represent a possible therapeutic target. Laser therapy should be considered for proliferative retinopathy in order to prevent visual loss; however, the evidence is not very strong. With recent development of wide-field imaging, targeted laser to ischemic retina may prove to be beneficial. Exact control of intraoperative intraocular pressure, including valved trocar vitrectomy systems, may improve the outcomes of vitreoretinal surgery for complications, such as vitreous hemorrhage and retinal detachment. Stem cell transplantation and gene therapy are potentially curative treatments, which may prevent retinopathy.

CONCLUSIONS

There is lack of evidence regarding the optimal management of sickle retinopathy. Further study is needed to determine if recent progress in the understanding of the pathophysiology and diagnosis of sickle retinopathy may translate into improved management and outcome.

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.

Analysis of Retinal Thinning Using Spectral-domain Optical Coherence Tomography Imaging of Sickle Cell Retinopathy Eyes Compared to Age- and Race-Matched Control Eyes

PURPOSE

To determine whether the retina is thinner in sickle cell patients than in race- and age-matched controls, and, if it is thinner, whether there is any association with systemic diseases.

METHODS

Sickle cell and control (age- and race-matched) patients were prospectively enrolled from a university retina clinic into this observational study. Participants underwent visual acuity testing, slit-lamp biomicroscopy, dilated ophthalmoscopy, and spectral-domain optical coherence tomography imaging. Sickle cell retinal lesions, degree of vascular tortuosity, caliber of arteriovenous anastomosis, and stage of retinopathy were noted. Early Treatment Diabetic Retinopathy Study (ETDRS) subfield measurements were compared between sickle cell and control subjects and also among sickle cell hemoglobin subtypes. Associations between ETDRS subfield measurements and hemoglobin subtype, retinopathy stage, and systemic diseases were assessed.

RESULTS

A total of 513 sickle cell eyes (260 patients) and 75 control eyes (39 patients) had median visual acuities of 20/20. ETDRS central (P = .002), inner (nasal P = .009, superior P = .021, temporal P < .001, inferior P = .017), and temporal outer (P = .012) subfield measurements were thinner in sickle cell eyes compared to control eyes. Hemoglobin SS eyes had significantly thinner inner ETDRS subfield measurements compared to SC and SThal eyes. Retinal thinning in all subfields was associated with age (P = .017) for sickle cell and control eyes. No association was found between retinal thinning and hydroxyurea use or arteriovenous anastomosis caliber.

CONCLUSIONS

The macula is thinner in sickle cell eyes compared to control eyes; retinal thickness decreases with increasing age and sickle cell retinopathy stage and is most severe in hemoglobin SS subtypes. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Funduscopic examination and SD-OCT in detecting sickle cell retinopathy among pediatric patients

PURPOSE

To compare the results of fundus examination and spectral domain optic coherence tomography (SD-OCT) in detecting retinal changes in pediatric patients with sickle cell disease at a single center.

METHODS

In this prospective study, conducted over a period of 19 months, consecutive African American patients with sickle cell disease underwent complete ophthalmologic examination, and SD-OCT images of the maculas of both eyes were obtained.

RESULTS

A total of 69 (37 males) patients aged 5-20 years (mean 12.89 ± 4.09; range, 2-20) with sickle cell disease (SC, 26; SS, 36; Sβ+, 5; Sβ0 thalassemia, 2) were examined. Patients' visual acuity range was 20/20 to 20/40. On funduscopic examination, 11 of 69 showed signs of retinopathy, whereas 47 of 68 showed inner retina thinning in the watershed zone temporal to the fovea on SD-OCT. On average, SD-OCT diagnosed disease 1.78 years earlier than fundus examination. Of patients <10 years of age, 1 was diagnosed with retinopathy by funduscopy, whereas retinal changes were evident on SD-OCT in 12 of 22. Fundus examination showed no significant difference in retinal findings between SS/Sβ0 and SC genotypes. On SD-OCT, SS/Sβ0 showed worse disease process than SC in frequency of diagnosis (82% vs 56%), bilateral involvement (87% vs 43%), and foveal involvement (18% vs 0).

CONCLUSIONS

The peripheral retina could be visualized on fundus examination but not easily imaged on SD-OCT, which, however, had a higher detection rate and offered earlier diagnosis. In our patient cohort SD-OCT showed that the severity of retinal change was associated with more severe sickle cell disease genotypes (SS and Sβ0).

Retinal thickness measurements in sickle cell patients with HbSS and HbSC genotype

OBJECTIVE

Temporal macula thinning has been reported in sickle cell patients, but it remains unclear if there is a difference between HbSS and HbSC genotypes. We aimed to quantitatively compare macular thickness between eyes with HbSS and HbSC genotype.

DESIGN

Retrospective descriptive study.

METHODS

Consecutive patients seen over a 5.5-year period in the Ophthalmology Department at St Thomas' Hospital, London, were identified. Macular optical coherence tomography images were retrospectively analyzed. The retinal thickness in all 9 subfields of the Early Treatment Diabetic Retinopathy Study (ETDRS) grid was compared between HbSS and HbSC eyes. Right eyes and left eyes were analyzed independently, as well as averaged measurements from both eyes. Comparison was made between the 2 genotypes, adjusting for age and sex, and for multiple testing. Scans were excluded in cases of poor fixation or ocular comorbidity affecting retinal thickness.

RESULTS

132 HbSC and 120 HbSS patients were identified. Scans from 166 right and 153 left eyes were included (with approximately equal numbers of HbSS and HbSC genotypes). Mean retinal thickness was lower in HbSS eyes compared with HbSC eyes in all subfields of the ETDRS grid, but in most subfields the difference was <10 microns. Differences reached statistical significance for outer superior, inferior, and temporal subfields and the inner temporal subfield (p < 0.05).

CONCLUSION

Although the HbSC genotype is more strongly associated with proliferative retinopathy, HbSS patients had on average more macular thinning.

Correlation of Ultra-Widefield Fluorescein Angiography and OCT Angiography in Sickle Cell Retinopathy

PURPOSE

To determine whether the degree of peripheral nonperfusion seen on ultra-widefield (UWF) fluorescein angiography (FA) correlates with measures of macular vascular flow as seen on OCT angiography (OCTA) in sickle cell retinopathy.

DESIGN

Prospective, observational study.

PARTICIPANTS

Patients with sickle cell disease undergoing an eye examination at an urban, tertiary medical center.

METHODS

All patients underwent dilated fundus examination as well as UWF FA and macular OCTA imaging on the same day. The peripheral nonperfusion seen on UWF FA was measured to calculate an ischemic index (visualized nonperfusion/total visualized retinal area × 100%), and OCTA measurements of macular vessel density were recorded. The degree of peripheral nonperfusion and vessel density were then correlated.

MAIN OUTCOME MEASURES

Correlation between ischemic index as seen on UWF FA and macular vessel density on OCTA.

RESULTS

Thirty-six eyes from 19 patients (10 women, 9 men) with a mean age of 30.8 years were included. Sickle genotypes included 14 patients with SS (73.7%), 4 with SC (21.1%), and 1 with β-thalassemia (5.2%). Average ischemic index was 4.4% for all eyes and was found to be higher in patients with sickle SC (8.0%) than in those with sickle SS (3.2%; P = 0.01). Ischemic index also was higher in those with proliferative sickle cell retinopathy (9.3%) than in those without (2.8%; P < 0.01). Ischemic index on UWF FA showed a statistically significant correlation (P < 0.05) with vessel density on OCTA in the temporal subfield of the superficial capillary plexus and in all subfields of the deep capillary plexus.

CONCLUSIONS

Peripheral nonperfusion seen on UWF FA is greater in those with sickle SC disease and proliferative retinopathy and is correlated with macular vessel density on OCTA, especially the deep retinal plexus.

New Ways to Detect Pediatric Sickle Cell Retinopathy: A Comprehensive Review

Sickle retinopathy reflects disease-related vascular injury of the eye, which can potentially result in visual loss from vitreous hemorrhage or retinal detachment. Here we review sickle retinopathy among children with sickle cell disease, describe the epidemiology, pediatric risk factors, pathophysiology, ocular findings, and treatment. Newer, more sensitive ophthalmological imaging modalities are available for retinal imaging, including ultra-widefield fluorescein angiography, spectral-domain optical coherence tomography, and optical coherence tomography angiography. Optical coherence tomography angiography provides a noninvasive view of retinal vascular layers that could previously not be imaged and can be quantified for comparative or prospective analyses. Ultra-widefield fluorescein angiography provides a more comprehensive view of the peripheral retina than traditional imaging techniques. Screening for retinopathy by standard fundoscopic imaging modalities detects a prevalence of approximately 10%. In contrast, these more sensitive methods allow for more sensitive examination that includes the retina perimeter where sickle retinopathy is often first detectable. Use of these new imaging modalities may detect a higher prevalence of early sickle pathology among children than has previously been reported. Earlier detection may help in better understanding the pathogenesis of sickle retinopathy and guide future screening and treatment paradigms.

Visual Function in Asymptomatic Patients With Homozygous Sickle Cell Disease and Temporal Macular Atrophy

Importance

Temporal macular involvement in sickle cell disease can now easily be detected by optical coherence tomography (OCT). However, while recent studies have demonstrated its high prevalence, little is known about its potential consequences on visual function.

Objective

To assess the visual function of patients with sickle cell disease with no visual symptoms despite temporal macular atrophy.

Design, Setting, and Participants

This retrospective case series included data collection and explorations made in a single referral center for sickle cell disease in 2016. Three patients with sickle cell disease exhibiting preserved visual acuity but showing temporal macular retinal atrophy were included.

Exposures

Patients underwent the following explorations: best-corrected distance and near visual acuity evaluation; dilated fundus examination; OCT with 12 × 6-mm thickness map; horizontal, vertical, and en face sections; OCT angiography of the 6 × 6-mm perifoveal retina; 30° and 12° central visual fields; Lanthony 15-hue color vision test; automated static contrast sensitivity test; and global electroretinography.

Main Outcomes and Measures

The OCT thickness maps were checked for areas of retinal thinning, appearing as blue patches. When present, these areas were compared with the areas of superficial and deep capillary flow loss on OCT angiography and with the scotomas on visual fields. Contrast sensitivity and color vision loss were quantified.

Results

All 3 patients included had homozygous sickle cell disease. They presented with a 20/20 distance visual acuity, and Parinaud 1,5 near visual acuity in both eyes. They were all followed up for a severe cerebral vasculopathy related to sickle cell disease. The areas of atrophy involved the inner retinal layers and were associated with an absence of signal in the deep capillary plexuses in OCT angiography. These patches of retinal thinning were also matching with scotomas in the automated visual fields. Color vision ability and contrast sensitivity were impaired in all patients. Global electroretinography findings were normal.

Conclusions and Relevance

Temporal macular atrophy in sickle cell disease may have direct consequences on visual function, including in children, even when visual acuity is preserved. Optical coherence tomographic imaging may be warranted when evaluating patients with sickle cell disease, even if asymptomatic with 20/20 visual acuity.

Sickle cell disease and the eye

PURPOSE OF REVIEW

To review recent literature pertaining to sickle cell retinopathy (SCR) and, in particular, sickle cell maculopathy.

RECENT FINDINGS

Several recent studies suggest that macular perfusion abnormalities seen in patients with sickle cell disease of various genotypes may affect both the superficial and deep capillary plexi, with a predilection for the deep capillary plexus. Further, these changes may be associated with areas of macular thinning, as well as with peripheral retinal ischemia, even in individuals without visual symptoms, contrary to what has previously been described in both diabetic retinopathy and retinal vein occlusion. Several cases also suggest that paracentral acute middle maculopathy may be the pathophysiologic mechanism by which microvascular occlusion leads to macular thinning.

SUMMARY

Sickle cell disease can manifest in a number of ways within the orbit as well as intraocularly because of its nonspecific vasoocclusive episodes. However, SCR is the most common ophthalmic manifestation of this disease. Historically, SCR has been considered a peripheral retinopathy, but the development and use of spectral-domain optical coherence tomography and optical coherence tomography angiography suggest that significant macular vascular changes occur early in this disease, even in asymptomatic individuals.

Sickle cell retinopathy: improving care with a multidisciplinary approach

Sickle cell retinopathy (SCR) is the most representative ophthalmologic complication of sickle cell disease (SCD), a hemoglobinopathy affecting both adults and children. SCR presents a wide spectrum of manifestations and may even lead to irreversible vision loss if not properly diagnosed and treated at the earliest. Over the past decade, multidisciplinary research developments have focused upon systemic, genetic, and ocular risk factors of SCR, enabling the clinician to better diagnose and manage these patients. In addition, newer imaging and testing modalities, such as spectral domain-optical coherence tomography angiography, have resulted in the detection of subclinical retinopathy related to SCD. Innovative therapy includes intravitreal injection of an anti-vascular endothelial growth factor (eg, Lucentis^® [ranibizumab] or Eylea^® [aflibercept]) which appears comparatively safe and efficient, and may be combined with laser photocoagulation (LPC) for proliferative SCR. The effect of LPC alone does not significantly lead to the regression of advanced SCR, although it helps in avoiding hemorrhage and sight loss. This comprehensive article is based on 10-years retrospective (2007–2017) studies. It aims to present advances and recommendations in SCR theranostics while pointing out the requirement of combinatorial approaches for better management of SCR patients. To reach this goal, we identified and analyzed randomized original and review articles, clinical trials, non-randomized intervention studies, and observational studies using specified keywords in various databases (eg, Medline, Embase, Cochrane, ClinicalTrials.gov).

Evaluation of Macular Vascular Abnormalities Identified by Optical Coherence Tomography Angiography in Sickle Cell Disease

PURPOSE

To evaluate macular vascular flow abnormalities identified by optical coherence tomography angiography (OCT-A) in patients with various sickle cell genotypes.

DESIGN

Prospective, observational case series.

METHODS

This is a single-institution case series of adult patients with various sickle cell genotypes. All patients underwent macular OCT-A (Avanti RTVue XR). Images were analyzed qualitatively for areas of flow loss and quantitatively for measures of foveal avascular area, parafoveal flow, and vascular density. The findings were compared by sickle cell genotype and retinopathy stage and correlated to retinal thickness and visual acuity.

RESULTS

OCT-A scans of 82 eyes from 46 patients (60.9% female, mean age 33.5 years) were included. Sickle cell genotypes included 27 patients with hemoglobin SS (58.7%), 14 SC (30.4%), 4 beta-thalassemia (8.7%), and 1 sickle trait (2.2%). Discrete areas of flow loss were noted in 37.8% (31/82) of eyes overall and were common in both SS (40.0%, 20/50 eyes) and SC (41.7%, 10/24 eyes). Flow loss was more extensive in the temporal and nasal parafoveal subfields of the deep plexus with sickle SC or proliferative retinopathy. Retinal thickness measurements correlated with vascular density of the fovea, parafovea, and temporal and superior subfields. Visual acuity correlated with foveal avascular zone area and parafoveal vascular density in the superficial and deep plexi.

CONCLUSIONS

Areas of abnormal macular vascular flow are common in patients with various sickle cell genotypes. These areas may be seen at any retinopathy stage but may be more extensive with sickle SC or proliferative retinopathy.

CORRELATION OF MULTIMODAL IMAGING IN SICKLE CELL RETINOPATHY

PURPOSE

To correlate macular findings on spectral domain optical coherence tomography (SDOCT) and optical coherence tomography angiography (OCTA) with quantitative ischemic index calculations on ultra-wide-field fluorescein angiography (UWFFA) in patients with sickle cell retinopathy.

METHODS

In this retrospective case series, SDOCT, OCTA, and UWFFA images of patients with sickle cell retinopathy were evaluated. Eyes were staged based on the Goldberg classification of proliferative sickle cell retinopathy. Focal areas of macular thinning were assessed on SDOCT, macular vessel density was derived from OCTA, and peripheral ischemic index was calculated from UWFFA.

RESULTS

Eighteen eyes of 10 patients were included. Mean age was 36.8 ± 16.8 years, and 6 patients (11 eyes) were SS, 3 patients (5 eyes) were SC, and 1 patient (2 eyes) was Sβ thalassemia in hemoglobin electrophoresis. Abnormal macular findings included inner retinal atrophy in 11 eyes (61%) on SDOCT, vascular remodeling and nonperfusion in the superficial and deep retinal capillary plexus in 12 eyes (67%) on OCTA, and macular microvascular abnormalities in 9 eyes (50%) on UWFFA. Sickle cell retinopathy Stage I was identified in 4 eyes (22.2%), Stage II in 8 eyes (44.4%), and Stage III in 6 eyes (33.3%). Mean ischemic index was 14.1 ± 9.1%. Ischemic index was significantly correlated with hemoglobinopathy subtype (23.7 ± 9.8%, 9.3 ± 5.4%, and 16.3 ± 3.2%, for SC, SS, and Sβ thalassemia disease, respectively), stage of sickle cell retinopathy (22.5 ± 9.2%, 12.5 ± 4.9%, and 4.5 ± 0.73% for Stages III, II, and I, respectively), and presence of retinal thinning on SDOCT (17.4 ± 9.7% vs. 8.8 ± 5.1%, respectively).

CONCLUSION

Multimodal imaging can provide a more complete description of the microvascular and structural alterations associated with sickle retinopathy. The correlation between the severity of peripheral nonperfusion and stage and subtype of retinopathy suggests that UWF imaging may be a useful tool in the evaluation of these patients.

Conjunctival microvascular hemodynamics following vaso-occlusive crisis in sickle cell disease

Painful vaso-occlusive crisis (VOC) is the clinical hallmark of sickle cell disease (SCD). Microcirculatory hemodynamic changes following painful VOC may be indicative of future development of VOC events in subjects with SCD. The purpose of the present study was to determine alterations in conjunctival microvascular hemodynamics during non-crisis state in SCD subjects with a history of VOC. Conjunctival microcirculation imaging was performed to measure conjunctival diameter (D) and axial blood velocity (V) in 10 control and 30 SCD subjects. SCD subjects were categorized into two groups based on their history of VOC within a 2-year period before imaging (with or without VOC-H) and also based on whether there was progression in the rate of VOCs during a 2-year period following imaging as compared to before imaging (with or without VOC-P). Conjunctival V was significantly higher in SCD subjects with VOC-H than in both control subjects and SCD subjects without VOC-H (P≤0.03). Conjunctival V was also significantly higher in SCD subjects with VOC-P compared with control subjects and SCD subjects without VOC-P (P≤0.03). Assessment of the conjunctival microcirculation may be useful for understanding hemodynamic changes that lead to VOC events in SCD subjects.

Temporal Macular Atrophy as a Predictor of Neovascularization in Sickle Cell Retinopathy

BACKGROUND AND OBJECTIVE

To evaluate the association between temporal macular atrophy and the presence of neovascularization in eyes with sickle cell disease (SCD).

PATIENTS AND METHODS

Retrospective, case-controlled study identifying 64 eyes from 38 consecutive patients with SCD. Dilated funduscopic examination and wide-field fluorescein angiography were used to identify the Goldberg stage of proliferative sickle cell retinopathy. Spectral-domain optical coherence tomography images were analyzed for the presence of temporal macular atrophy. The association between temporal macular atrophy and neovascularization was then evaluated.

RESULTS

Temporal macular atrophy had a sensitivity of 27%, a specificity of 67%, a positive predictive value of 83%, and a negative predictive value of 13% for identifying neovascularization.

CONCLUSION

Although the presence of temporal macular atrophy is not sensitive enough to be used as a screening test, if seen in a patient with SCD, the physician should be alerted to the strong possibility that peripheral neovascularization may be present.

Cross-Sectional Analysis of Neurocognitive Function, Retinopathy, and Retinal Thinning by Spectral-Domain Optical Coherence Tomography in Sickle Cell Patients

Purpose:

The purpose was to examine the relationship between neurocognitive function and two distinct forms of retinopathy in sickle cell disease.

Materials and Methods:

Patients with sickle cell disease (n = 44, age range: 19-56 years, 70% female) were prospectively recruited for this cross-sectional study. Retinopathy was characterized by: (1) Presence of focal retinal thinning on spectral domain optical coherence tomography and (2) determination of the sickle retinopathy stage on funduscopic exam based on Goldberg classification. Neurocognitive function was assessed using the Philadelphia Brief Assessment of Cognition (PBAC), a validated test of cognition. Univariate and multivariate analyses for PBAC score outcomes were performed. Retinal thinning and retinopathy stage were primary variables of interest and age, gender, genotype, education, and history of stroke were covariates.

Results:

Univariate analysis revealed associations with total PBAC score and age (P = 0.049), history of stroke (P = 0.04), and genotype (P < 0.001). Focal retinal thinning and Goldberg retinopathy stage were not associated with each other in this sample. Neither the presence of focal retinal thinning nor degree of retinopathy was associated with total PBAC score in univariate or multivariate analyses.

Conclusions:

We find an association between lower cognitive function and older age, history of stroke and sickle cell genotype SS in patients with sickle cell disease. Our data do not provide evidence to support an association between cognitive function and retinopathy in sickle cell patients.

Macular Microangiopathy in Sickle Cell Disease Using Optical Coherence Tomography Angiography

PURPOSE

To characterize the optical coherence tomography angiography (OCTA) appearance of the perifoveal macular microvasculature in visually asymptomatic patients with sickle cell disease, and to compare these findings with those of fluorescein angiography (FA).

DESIGN

Retrospective observational case series.

METHODS

Eighteen eyes of 9 consecutive patients with a median age of 41 years (range: 19-54 years) with electrophoretic confirmation of sickle cell disease were included and analyzed. A complete ophthalmologic examination was performed, including fundus examination, FA, and OCTA. Nine eyes of 5 healthy subjects were also analyzed with OCTA to serve as a control group.

RESULTS

OCTA demonstrated microvascular abnormalities in the perifoveal region of the macula in all eyes, whereas FA appeared normal in 9 of 18 eyes (50%). Most capillary abnormalities were located in the temporal juxtafoveal region and involved both the superficial and the deep capillary plexuses. The nonflow area (foveal avascular zone) was significantly larger in sickle cell disease patients than in the control group, both in the superficial and the deep capillary plexuses (P < .0001). The perifoveal vessel density was significantly lower in the sickle cell disease patients than in the control group in both the superficial (P = .0011) and the deep capillary plexuses (P = .0018).

CONCLUSION

OCTA provided detailed imaging of the perifoveal microvasculature in sickle cell disease. It appeared more sensitive than FA in detecting macular microangiopathy in asymptomatic patients. Microvascular abnormalities in sickle cell disease involved both the superficial and the deep capillary plexuses.

Changes in Conjunctival Hemodynamics Predict Albuminuria in Sickle Cell Nephropathy

BACKGROUND

Albuminuria is an early manifestation of deterioration in renal function in subjects with sickle cell disease (SCD). Hyperfiltration may be an early mechanism for kidney damage in SCD. The purpose of the current study was to determine the association between conjunctival hemodynamics and albuminuria in SCD subjects with preserved glomerular filtration rate.

METHODS

Conjunctival microcirculation imaging was performed to measure conjunctival diameter and axial blood velocity (V) in 35 SCD and 10 healthy control subjects. Albuminuria, defined as albumin excretion ratio (AER), was obtained from the medical charts. Based on the 95% CI of conjunctival V in control subjects (0.40-0.60 mm/s), SCD subjects were allocated to 3 groups: V1 <0.40 mm/s (n = 7), V2 of 0.40-0.60 mm/s (n = 18) and V3 ≥0.60 mm/s (n = 10).

RESULTS

Mean log(AER) measurements in the V1, V2 and V3 groups were 1.08 ± 0.67, 1.39 ± 0.59 and 2.00 ± 0.91 mg/g creatinine, respectively, and followed a positive linear trend from the V1 to V3 groups (p = 0.01). By multivariate linear regression analysis, conjunctival V significantly correlated with albuminuria (p = 0.01) independent of age, blood pressure, α-thalassemia, hematocrit, white blood cell count and lactate dehydrogenase concentration.

CONCLUSIONS

Increased conjunctival V is associated with albuminuria in SCD subjects. Assessment of conjunctival microvascular hemodynamics may improve our understanding of the pathophysiology and clinical management of sickle cell nephropathy.

Conjunctival microvascular haemodynamics in sickle cell retinopathy

PURPOSE

To determine alterations in bulbar conjunctival microvascular haemodynamics in sickle cell retinopathy (SCR) subjects with focal macular thinning (FMT).

METHODS

Conjunctival microcirculation imaging and spectral domain optical coherence tomography (SD-OCT) were performed in 22 subjects (eyes) diagnosed with SCR. Based on evaluation of SD-OCT retinal thickness maps, eyes were assigned to one of the two groups: with or without FMT. Conjunctival venular diameter and axial blood velocity were measured in multiple venules in each eye by customized image analysis algorithms. Measurements were then categorized into two vessel size groups (vessel size 1 and 2) and compared between FMT groups. A Pearson correlation coefficient was computed to assess the relationship between retinal thickness and axial blood velocity.

RESULTS

Mean age, haematocrit, sickle cell haemoglobin type and median retinopathy score were not significantly different between the two groups (p ≥ 0.1). Retinal thickness in parafoveal and perifoveal temporal subfields was significantly lower in eyes with FMT as compared to eyes without FMT (p ≤ 0.04). There was a significant effect of FMT on axial blood velocity (p = 0.04), while the effect of vessel size was not significant (p = 0.4). In vessel size 1, axial blood velocity was lower in eyes with FMT than in eyes without FMT (p = 0.03), while in vessel size 2, there was no statistically significant difference between FMT groups (p = 0.1). In vessel size 1, there was a significant positive correlation between axial blood velocity and retinal thickness in the perifoveal (r = 0.48, p = 0.02) and parafoveal (r = 0.43, p = 0.04) temporal subfields.

CONCLUSION

Conjunctival axial blood velocity in small venules is reduced in SCR subjects with focal macular thinning.

Changes in the cornea related to sickle cell disease: a pilot investigation

PURPOSE

To investigate corneal structural changes (central corneal thickness, endothelial cell count, and cellular morphology) in patients with sickle cell disease (SCD).

METHODS

This prospective study included 56 patients with SCD and 50 age- and sex-matched healthy subjects without any eye disease aside from refractive errors. Endothelial cell density (ECD), percentage of hexagonality, and the coefficient of variation in cell size (CV) were measured using noncontact specular microscopy, and central corneal thickness (CCT) was measured by pachymetry.

RESULTS

The mean CCT value was 509.6 ± 20.7 μm in the study group and 520.8 ± 23.6 μm in the control group. The mean ECD, CV, and percentage of hexagonality values in the study group were 2712 ± 335 cells/mm², 34.5 ± 5.3%, and 57.2 ± 6.6%, respectively, and 3030 ± 247 cells/mm², 31.6 ± 5.0%, and 60.4 ± 6.9% in the control group, respectively. Endothelial cell density (p = 0.001), CCT (p = 0.011), CV (p = 0.005), and percentage of hexagonality values (p = 0.018) were significantly different between the study and control groups.

CONCLUSIONS

The results of the current study indicate that patients with SCD had considerable morphologic changes in the structure of the cornea when compared to healthy subjects.

Peripapillary retinal nerve fiber layer thickness in sickle-cell hemoglobinopathies using spectral-domain optical coherence tomography

PURPOSE

To determine whether patients with a sickle-cell hemoglobinopathy without glaucoma have peripapillary retinal nerve fiber layer (RNFL) thinning by spectral-domain optical coherence tomography.

DESIGN

Prospective study.

METHODS

All patients with a sickle cell hemoglobinopathy (sickle-cell disease, sickle-cell hemoglobin C disease, and sickle-cell thalassemia) and age-similar, race-matched controls underwent a comprehensive eye examination and spectral-domain optical coherence tomography of the macula and optic nerve head using the Heidelberg Spectralis (Heidelberg Engineering, Inc, Carlsbad, California, USA). Participants with prior retinal treatments (laser or surgery), diabetes mellitus, glaucoma, or other ocular diseases were excluded. The sickle-cell disease patients were grouped into those with focal macular thinning and those without. Those with macular thinning were grouped further into mild, moderate, and severe thinning groups based on temporal macular thickness. Analysis of variance testing and post hoc analysis with the Tukey test and Pearson correlation were performed to assess for peripapillary RNFL thickness differences among different groups.

RESULTS

One hundred fifty-one eyes of 88 sickle-cell patients and 55 eyes of 30 age-similar and race-matched (black) controls were included. Sickle-cell patient eyes with macular thinning (n = 81) had thinner mean peripapillary RNFL thicknesses in the nasal sector (P = .01) compared with non-sickle-cell control eyes and in the superotemporal sector (P = .01) compared with sickle-cell patient eyes without macular thinning (n = 70). In the severe macular thinning subgroup (n = 55), the mean peripapillary RNFL thickness was significantly thinner than that of controls (P < .05) in 6 of 7 sectors. There is a positive linear relationship between temporal macular thickness and global peripapillary RNFL thickness with a Pearson correlation coefficient of 0.60 (P < .0001).

CONCLUSIONS

Nonglaucomatous, black sickle-cell patients with focal macular thinning on spectral-domain optical coherence tomography have significantly thinner peripapillary RNFL than those without macular thinning or controls. The degree of thinning correlates with severity of temporal macular thinning. These patients may require different peripapillary RNFL thickness thresholds for future glaucoma evaluations.